AQL Query Language
Learn how to integrate AQL queries seamlessly into MTL templates for powerful model-driven code generation.
In this tutorial, you’ll discover how AQL expressions work within MTL templates, how to navigate models during code generation, and how to build sophisticated template logic using AQL’s querying capabilities.
Section 1
AQL serves as the expression language within MTL templates. Every dynamic expression in an MTL template—from simple property access to complex model queries—uses AQL syntax.
This tight integration makes MTL templates both powerful and intuitive: you can navigate models naturally while generating code, creating templates that adapt to model structure and content.
Step 1
Set up a model for code generation examples.
This metamodel represents a web application with Controllers, Models, and Views. We’ll use this to demonstrate how AQL queries drive code generation patterns.
1<?xml version="1.0" encoding="UTF-8"?>2<ecore:EPackage xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"3 xmlns:ecore="http://www.eclipse.org/emf/2002/Ecore"4 name="WebApp" nsURI="http://www.example.org/webapp" nsPrefix="webapp">56 <!-- WebApp: Root container for the web application -->7 <eClassifiers xsi:type="ecore:EClass" name="WebApp">8 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"9 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>10 <eStructuralFeatures xsi:type="ecore:EAttribute" name="baseUrl"11 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>12 <eStructuralFeatures xsi:type="ecore:EAttribute" name="version"13 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>14 <eStructuralFeatures xsi:type="ecore:EReference" name="pages" upperBound="-1"15 eType="#//Page" containment="true"/>16 <eStructuralFeatures xsi:type="ecore:EReference" name="entities" upperBound="-1"17 eType="#//Entity" containment="true"/>18 <eStructuralFeatures xsi:type="ecore:EReference" name="stylesheets" upperBound="-1"19 eType="#//Stylesheet" containment="true"/>20 </eClassifiers>2122 <!-- Page: Represents a web page with a route -->23 <eClassifiers xsi:type="ecore:EClass" name="Page">24 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"25 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>26 <eStructuralFeatures xsi:type="ecore:EAttribute" name="route" lowerBound="1"27 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>28 <eStructuralFeatures xsi:type="ecore:EAttribute" name="title"29 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>30 <eStructuralFeatures xsi:type="ecore:EAttribute" name="requiresAuth"31 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>32 <eStructuralFeatures xsi:type="ecore:EReference" name="components" upperBound="-1"33 eType="#//Component" containment="true"/>34 <eStructuralFeatures xsi:type="ecore:EReference" name="linkedPages" upperBound="-1"35 eType="#//Page"/>36 </eClassifiers>3738 <!-- Component: Abstract base for UI components -->39 <eClassifiers xsi:type="ecore:EClass" name="Component" abstract="true">40 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"41 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>42 <eStructuralFeatures xsi:type="ecore:EAttribute" name="cssClass"43 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>44 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isVisible"45 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="true"/>46 </eClassifiers>4748 <!-- Form: Input form with fields and validation -->49 <eClassifiers xsi:type="ecore:EClass" name="Form" eSuperTypes="#//Component">50 <eStructuralFeatures xsi:type="ecore:EAttribute" name="action"51 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>52 <eStructuralFeatures xsi:type="ecore:EAttribute" name="method"53 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString" defaultValueLiteral="POST"/>54 <eStructuralFeatures xsi:type="ecore:EReference" name="fields" upperBound="-1"55 eType="#//Field" containment="true"/>56 <eStructuralFeatures xsi:type="ecore:EReference" name="boundEntity"57 eType="#//Entity"/>58 </eClassifiers>5960 <!-- Field: Form input field -->61 <eClassifiers xsi:type="ecore:EClass" name="Field">62 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"63 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>64 <eStructuralFeatures xsi:type="ecore:EAttribute" name="label"65 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>66 <eStructuralFeatures xsi:type="ecore:EAttribute" name="fieldType" lowerBound="1"67 eType="#//FieldType"/>68 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isRequired"69 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>70 <eStructuralFeatures xsi:type="ecore:EAttribute" name="placeholder"71 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>72 <eStructuralFeatures xsi:type="ecore:EAttribute" name="validationPattern"73 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>74 <eStructuralFeatures xsi:type="ecore:EReference" name="boundAttribute"75 eType="#//Attribute"/>76 </eClassifiers>7778 <!-- FieldType: Enumeration of input types -->79 <eClassifiers xsi:type="ecore:EEnum" name="FieldType">80 <eLiterals name="text" value="0"/>81 <eLiterals name="email" value="1"/>82 <eLiterals name="password" value="2"/>83 <eLiterals name="number" value="3"/>84 <eLiterals name="date" value="4"/>85 <eLiterals name="textarea" value="5"/>86 <eLiterals name="select" value="6"/>87 <eLiterals name="checkbox" value="7"/>88 <eLiterals name="hidden" value="8"/>89 </eClassifiers>9091 <!-- DataTable: Displays tabular data -->92 <eClassifiers xsi:type="ecore:EClass" name="DataTable" eSuperTypes="#//Component">93 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isPaginated"94 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="true"/>95 <eStructuralFeatures xsi:type="ecore:EAttribute" name="pageSize"96 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EInt" defaultValueLiteral="10"/>97 <eStructuralFeatures xsi:type="ecore:EReference" name="columns" upperBound="-1"98 eType="#//Column" containment="true"/>99 <eStructuralFeatures xsi:type="ecore:EReference" name="dataSource"100 eType="#//Entity"/>101 </eClassifiers>102103 <!-- Column: Table column definition -->104 <eClassifiers xsi:type="ecore:EClass" name="Column">105 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"106 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>107 <eStructuralFeatures xsi:type="ecore:EAttribute" name="header"108 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>109 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isSortable"110 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>111 <eStructuralFeatures xsi:type="ecore:EAttribute" name="width"112 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>113 <eStructuralFeatures xsi:type="ecore:EReference" name="boundAttribute"114 eType="#//Attribute"/>115 </eClassifiers>116117 <!-- Navigation: Menu or navigation component -->118 <eClassifiers xsi:type="ecore:EClass" name="Navigation" eSuperTypes="#//Component">119 <eStructuralFeatures xsi:type="ecore:EAttribute" name="navType"120 eType="#//NavType" defaultValueLiteral="horizontal"/>121 <eStructuralFeatures xsi:type="ecore:EReference" name="items" upperBound="-1"122 eType="#//NavItem" containment="true"/>123 </eClassifiers>124125 <!-- NavType: Navigation layout type -->126 <eClassifiers xsi:type="ecore:EEnum" name="NavType">127 <eLiterals name="horizontal" value="0"/>128 <eLiterals name="vertical" value="1"/>129 <eLiterals name="dropdown" value="2"/>130 </eClassifiers>131132 <!-- NavItem: Navigation menu item -->133 <eClassifiers xsi:type="ecore:EClass" name="NavItem">134 <eStructuralFeatures xsi:type="ecore:EAttribute" name="label" lowerBound="1"135 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>136 <eStructuralFeatures xsi:type="ecore:EAttribute" name="icon"137 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>138 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isActive"139 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>140 <eStructuralFeatures xsi:type="ecore:EReference" name="targetPage"141 eType="#//Page"/>142 <eStructuralFeatures xsi:type="ecore:EReference" name="subItems" upperBound="-1"143 eType="#//NavItem" containment="true"/>144 </eClassifiers>145146 <!-- Entity: Data model entity -->147 <eClassifiers xsi:type="ecore:EClass" name="Entity">148 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"149 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>150 <eStructuralFeatures xsi:type="ecore:EAttribute" name="tableName"151 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>152 <eStructuralFeatures xsi:type="ecore:EReference" name="attributes" upperBound="-1"153 eType="#//Attribute" containment="true"/>154 <eStructuralFeatures xsi:type="ecore:EReference" name="relationships" upperBound="-1"155 eType="#//Relationship" containment="true"/>156 </eClassifiers>157158 <!-- Attribute: Entity property -->159 <eClassifiers xsi:type="ecore:EClass" name="Attribute">160 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"161 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>162 <eStructuralFeatures xsi:type="ecore:EAttribute" name="dataType" lowerBound="1"163 eType="#//DataType"/>164 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isPrimaryKey"165 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>166 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isNullable"167 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="true"/>168 <eStructuralFeatures xsi:type="ecore:EAttribute" name="defaultValue"169 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>170 <eStructuralFeatures xsi:type="ecore:EAttribute" name="maxLength"171 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EInt"/>172 </eClassifiers>173174 <!-- DataType: Attribute data types -->175 <eClassifiers xsi:type="ecore:EEnum" name="DataType">176 <eLiterals name="string" value="0"/>177 <eLiterals name="integer" value="1"/>178 <eLiterals name="decimal" value="2"/>179 <eLiterals name="boolean" value="3"/>180 <eLiterals name="date" value="4"/>181 <eLiterals name="datetime" value="5"/>182 <eLiterals name="text" value="6"/>183 </eClassifiers>184185 <!-- Relationship: Entity relationship -->186 <eClassifiers xsi:type="ecore:EClass" name="Relationship">187 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"188 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>189 <eStructuralFeatures xsi:type="ecore:EAttribute" name="relationType" lowerBound="1"190 eType="#//RelationType"/>191 <eStructuralFeatures xsi:type="ecore:EReference" name="targetEntity" lowerBound="1"192 eType="#//Entity"/>193 </eClassifiers>194195 <!-- RelationType: Relationship cardinality -->196 <eClassifiers xsi:type="ecore:EEnum" name="RelationType">197 <eLiterals name="oneToOne" value="0"/>198 <eLiterals name="oneToMany" value="1"/>199 <eLiterals name="manyToOne" value="2"/>200 <eLiterals name="manyToMany" value="3"/>201 </eClassifiers>202203 <!-- Stylesheet: CSS stylesheet reference -->204 <eClassifiers xsi:type="ecore:EClass" name="Stylesheet">205 <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1"206 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>207 <eStructuralFeatures xsi:type="ecore:EAttribute" name="path"208 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>209 <eStructuralFeatures xsi:type="ecore:EAttribute" name="isExternal"210 eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean" defaultValueLiteral="false"/>211 </eClassifiers>212213</ecore:EPackage>Step 2
Create a model instance for the web application.
This model defines a simple web application with user management functionality. The model provides rich data for demonstrating AQL-driven template generation.
1<?xml version="1.0" encoding="UTF-8"?>2<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"3 xmlns:webapp="http://www.example.org/webapp">45 <webapp:WebApp name="TaskManager" baseUrl="https://tasks.example.com" version="1.0.0">67 <!-- Data Entities -->8 <entities name="User" tableName="users">9 <attributes name="id" dataType="integer" isPrimaryKey="true" isNullable="false"/>10 <attributes name="email" dataType="string" isNullable="false" maxLength="255"/>11 <attributes name="username" dataType="string" isNullable="false" maxLength="50"/>12 <attributes name="passwordHash" dataType="string" isNullable="false"/>13 <attributes name="createdAt" dataType="datetime" isNullable="false"/>14 <attributes name="isActive" dataType="boolean" defaultValue="true"/>15 <relationships name="tasks" relationType="oneToMany" targetEntity="//@entities.1"/>16 <relationships name="projects" relationType="manyToMany" targetEntity="//@entities.2"/>17 </entities>1819 <entities name="Task" tableName="tasks">20 <attributes name="id" dataType="integer" isPrimaryKey="true" isNullable="false"/>21 <attributes name="title" dataType="string" isNullable="false" maxLength="200"/>22 <attributes name="description" dataType="text" isNullable="true"/>23 <attributes name="priority" dataType="integer" defaultValue="1"/>24 <attributes name="dueDate" dataType="date" isNullable="true"/>25 <attributes name="isCompleted" dataType="boolean" defaultValue="false"/>26 <attributes name="createdAt" dataType="datetime" isNullable="false"/>27 <relationships name="assignee" relationType="manyToOne" targetEntity="//@entities.0"/>28 <relationships name="project" relationType="manyToOne" targetEntity="//@entities.2"/>29 <relationships name="comments" relationType="oneToMany" targetEntity="//@entities.3"/>30 </entities>3132 <entities name="Project" tableName="projects">33 <attributes name="id" dataType="integer" isPrimaryKey="true" isNullable="false"/>34 <attributes name="name" dataType="string" isNullable="false" maxLength="100"/>35 <attributes name="description" dataType="text" isNullable="true"/>36 <attributes name="startDate" dataType="date" isNullable="true"/>37 <attributes name="endDate" dataType="date" isNullable="true"/>38 <attributes name="budget" dataType="decimal" isNullable="true"/>39 <relationships name="tasks" relationType="oneToMany" targetEntity="//@entities.1"/>40 <relationships name="members" relationType="manyToMany" targetEntity="//@entities.0"/>41 </entities>4243 <entities name="Comment" tableName="comments">44 <attributes name="id" dataType="integer" isPrimaryKey="true" isNullable="false"/>45 <attributes name="content" dataType="text" isNullable="false"/>46 <attributes name="createdAt" dataType="datetime" isNullable="false"/>47 <relationships name="author" relationType="manyToOne" targetEntity="//@entities.0"/>48 <relationships name="task" relationType="manyToOne" targetEntity="//@entities.1"/>49 </entities>5051 <!-- Stylesheets -->52 <stylesheets name="Bootstrap" path="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" isExternal="true"/>53 <stylesheets name="Custom Styles" path="/css/app.css" isExternal="false"/>54 <stylesheets name="Font Awesome" path="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0/css/all.min.css" isExternal="true"/>5556 <!-- Pages -->57 <pages name="Dashboard" route="/" title="Dashboard - TaskManager" requiresAuth="true"58 linkedPages="//@pages.1 //@pages.2 //@pages.3 //@pages.4">5960 <!-- Main Navigation -->61 <components xsi:type="webapp:Navigation" name="MainNav" cssClass="navbar navbar-expand-lg" navType="horizontal">62 <items label="Dashboard" icon="fa-home" isActive="true" targetPage="//@pages.0"/>63 <items label="Tasks" icon="fa-tasks" targetPage="//@pages.1"/>64 <items label="Projects" icon="fa-folder" targetPage="//@pages.2">65 <subItems label="All Projects" targetPage="//@pages.2"/>66 <subItems label="New Project" targetPage="//@pages.3"/>67 </items>68 <items label="Profile" icon="fa-user" targetPage="//@pages.4"/>69 </components>7071 <!-- Recent Tasks Table -->72 <components xsi:type="webapp:DataTable" name="RecentTasks" cssClass="table table-striped"73 isPaginated="true" pageSize="5" dataSource="//@entities.1">74 <columns name="title" header="Task" isSortable="true" width="40%" boundAttribute="//@entities.1/@attributes.1"/>75 <columns name="priority" header="Priority" isSortable="true" width="15%" boundAttribute="//@entities.1/@attributes.3"/>76 <columns name="dueDate" header="Due Date" isSortable="true" width="20%" boundAttribute="//@entities.1/@attributes.4"/>77 <columns name="isCompleted" header="Status" isSortable="false" width="15%" boundAttribute="//@entities.1/@attributes.5"/>78 </components>79 </pages>8081 <pages name="TaskList" route="/tasks" title="Tasks - TaskManager" requiresAuth="true"82 linkedPages="//@pages.0 //@pages.2">8384 <!-- Tasks Navigation (reuse pattern) -->85 <components xsi:type="webapp:Navigation" name="TaskNav" cssClass="navbar" navType="horizontal">86 <items label="All Tasks" isActive="true" targetPage="//@pages.1"/>87 <items label="My Tasks" targetPage="//@pages.1"/>88 <items label="Completed" targetPage="//@pages.1"/>89 </components>9091 <!-- Full Tasks Table -->92 <components xsi:type="webapp:DataTable" name="AllTasks" cssClass="table table-hover"93 isPaginated="true" pageSize="20" dataSource="//@entities.1">94 <columns name="id" header="#" isSortable="true" width="5%" boundAttribute="//@entities.1/@attributes.0"/>95 <columns name="title" header="Title" isSortable="true" width="35%" boundAttribute="//@entities.1/@attributes.1"/>96 <columns name="description" header="Description" isSortable="false" width="30%" boundAttribute="//@entities.1/@attributes.2"/>97 <columns name="priority" header="Priority" isSortable="true" width="10%" boundAttribute="//@entities.1/@attributes.3"/>98 <columns name="dueDate" header="Due" isSortable="true" width="10%" boundAttribute="//@entities.1/@attributes.4"/>99 <columns name="isCompleted" header="Done" isSortable="true" width="10%" boundAttribute="//@entities.1/@attributes.5"/>100 </components>101102 <!-- New Task Form -->103 <components xsi:type="webapp:Form" name="NewTaskForm" cssClass="card p-4"104 action="/api/tasks" method="POST" boundEntity="//@entities.1">105 <fields name="title" label="Task Title" fieldType="text" isRequired="true"106 placeholder="Enter task title" boundAttribute="//@entities.1/@attributes.1"/>107 <fields name="description" label="Description" fieldType="textarea" isRequired="false"108 placeholder="Describe the task..." boundAttribute="//@entities.1/@attributes.2"/>109 <fields name="priority" label="Priority" fieldType="select" isRequired="true"110 boundAttribute="//@entities.1/@attributes.3"/>111 <fields name="dueDate" label="Due Date" fieldType="date" isRequired="false"112 boundAttribute="//@entities.1/@attributes.4"/>113 </components>114 </pages>115116 <pages name="Projects" route="/projects" title="Projects - TaskManager" requiresAuth="true"117 linkedPages="//@pages.0 //@pages.1 //@pages.3">118119 <!-- Projects Table -->120 <components xsi:type="webapp:DataTable" name="ProjectsTable" cssClass="table table-bordered"121 isPaginated="true" pageSize="10" dataSource="//@entities.2">122 <columns name="name" header="Project Name" isSortable="true" width="30%" boundAttribute="//@entities.2/@attributes.1"/>123 <columns name="description" header="Description" isSortable="false" width="40%" boundAttribute="//@entities.2/@attributes.2"/>124 <columns name="startDate" header="Start" isSortable="true" width="15%" boundAttribute="//@entities.2/@attributes.3"/>125 <columns name="endDate" header="End" isSortable="true" width="15%" boundAttribute="//@entities.2/@attributes.4"/>126 </components>127 </pages>128129 <pages name="NewProject" route="/projects/new" title="New Project - TaskManager" requiresAuth="true"130 linkedPages="//@pages.2">131132 <!-- New Project Form -->133 <components xsi:type="webapp:Form" name="ProjectForm" cssClass="card shadow p-4"134 action="/api/projects" method="POST" boundEntity="//@entities.2">135 <fields name="name" label="Project Name" fieldType="text" isRequired="true"136 placeholder="Enter project name" validationPattern="^[A-Za-z0-9 ]{3,100}$"137 boundAttribute="//@entities.2/@attributes.1"/>138 <fields name="description" label="Description" fieldType="textarea" isRequired="false"139 placeholder="Describe the project..." boundAttribute="//@entities.2/@attributes.2"/>140 <fields name="startDate" label="Start Date" fieldType="date" isRequired="true"141 boundAttribute="//@entities.2/@attributes.3"/>142 <fields name="endDate" label="End Date" fieldType="date" isRequired="false"143 boundAttribute="//@entities.2/@attributes.4"/>144 <fields name="budget" label="Budget" fieldType="number" isRequired="false"145 placeholder="0.00" boundAttribute="//@entities.2/@attributes.5"/>146 </components>147 </pages>148149 <pages name="Profile" route="/profile" title="Profile - TaskManager" requiresAuth="true"150 linkedPages="//@pages.0">151152 <!-- Profile Form -->153 <components xsi:type="webapp:Form" name="ProfileForm" cssClass="container mt-4"154 action="/api/users/profile" method="POST" boundEntity="//@entities.0">155 <fields name="email" label="Email Address" fieldType="email" isRequired="true"156 validationPattern="^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"157 boundAttribute="//@entities.0/@attributes.1"/>158 <fields name="username" label="Username" fieldType="text" isRequired="true"159 placeholder="Your username" boundAttribute="//@entities.0/@attributes.2"/>160 <fields name="currentPassword" label="Current Password" fieldType="password" isRequired="false"161 placeholder="Enter current password"/>162 <fields name="newPassword" label="New Password" fieldType="password" isRequired="false"163 placeholder="Enter new password"/>164 </components>165 </pages>166167 <pages name="Login" route="/login" title="Login - TaskManager" requiresAuth="false"168 linkedPages="//@pages.6">169170 <!-- Login Form -->171 <components xsi:type="webapp:Form" name="LoginForm" cssClass="card shadow-lg mx-auto"172 action="/api/auth/login" method="POST" boundEntity="//@entities.0">173 <fields name="email" label="Email" fieldType="email" isRequired="true"174 placeholder="your@email.com" boundAttribute="//@entities.0/@attributes.1"/>175 <fields name="password" label="Password" fieldType="password" isRequired="true"176 placeholder="Enter your password"/>177 <fields name="remember" label="Remember me" fieldType="checkbox" isRequired="false"/>178 </components>179 </pages>180181 <pages name="Register" route="/register" title="Register - TaskManager" requiresAuth="false"182 linkedPages="//@pages.5">183184 <!-- Registration Form -->185 <components xsi:type="webapp:Form" name="RegisterForm" cssClass="card shadow-lg mx-auto"186 action="/api/auth/register" method="POST" boundEntity="//@entities.0">187 <fields name="username" label="Username" fieldType="text" isRequired="true"188 placeholder="Choose a username" validationPattern="^[a-zA-Z0-9_]{3,20}$"189 boundAttribute="//@entities.0/@attributes.2"/>190 <fields name="email" label="Email" fieldType="email" isRequired="true"191 placeholder="your@email.com" validationPattern="^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"192 boundAttribute="//@entities.0/@attributes.1"/>193 <fields name="password" label="Password" fieldType="password" isRequired="true"194 placeholder="Create a password"/>195 <fields name="confirmPassword" label="Confirm Password" fieldType="password" isRequired="true"196 placeholder="Confirm your password"/>197 <fields name="terms" label="I accept the terms and conditions" fieldType="checkbox" isRequired="true"/>198 </components>199 </pages>200201 </webapp:WebApp>202</xmi:XMI>Step 3
Create a basic MTL template with AQL expressions.
This template shows how AQL expressions appear within MTL syntax. Square brackets contain AQL expressions that are evaluated during template execution.
1[comment encoding = UTF-8 /]2[module BasicTemplate('http://www.example.org/webapp')]34[comment]5 Basic MTL Template with AQL Expressions67 This template demonstrates how AQL expressions are embedded8 within MTL templates for model-to-text transformations.910 Key concept: AQL provides the query language for navigating11 and filtering model elements, whilst MTL provides the template12 structure for generating text output.13[/comment]1415[comment ================================================================ /]16[comment SIMPLE NAVIGATION /]17[comment ================================================================ /]1819[template main(app : WebApp)]20[comment]21 AQL navigation expressions access model properties directly.22 The expression 'app.name' navigates to the name attribute.23[/comment]24[file ('README.md', 'overwrite', 'UTF-8')]25# [app.name/]2627Version: [app.version/]28Base URL: [app.baseUrl/]2930## Overview3132This web application contains:33- [app.pages->size()/] pages34- [app.entities->size()/] data entities35- [app.stylesheets->size()/] stylesheets3637[comment]38 AQL's ->size() operation counts collection elements.39 This is one of the most common collection operations.40[/comment]4142## Pages4344[for (page : Page | app.pages)]45- **[page.name/]**: `[page.route/]`46[/for]4748## Entities4950[for (entity : Entity | app.entities)]51- [entity.name/] (table: [entity.tableName/])52[/for]5354Generated with swift-mtl55[/file]56[/template]Step 4
Generate code to see AQL expressions in action.
Run the template to see how AQL expressions are evaluated and their results inserted into the generated output. This demonstrates the fundamental AQL-MTL integration.
1# Basic MTL Generation with AQL Expressions2# This script demonstrates running a basic MTL template34# Run the basic template to generate documentation5swift-mtl generate \6 --template BasicGeneration.mtl \7 --model webapp-model.xmi \8 --metamodel WebApp.ecore \9 --output ./generated1011# Output directory structure:12# generated/13# README.md1415# Example generated README.md content:16# -----------------------------------------17# # TaskManager18#19# Version: 1.0.020# Base URL: https://tasks.example.com21#22# ## Overview23#24# This web application contains:25# - 7 pages26# - 4 data entities27# - 3 stylesheets28#29# ## Pages30#31# - **Dashboard**: `/`32# - **TaskList**: `/tasks`33# - **Projects**: `/projects`34# ...35# -----------------------------------------3637# The AQL expressions in the template are evaluated:38# [app.name/] -> TaskManager39# [app.version/] -> 1.0.040# [app.pages->size()/] -> 741# [app.entities->size()/] -> 44243# View the generated file44cat ./generated/README.mdSection 3
AQL’s collection operations become particularly powerful within MTL templates. They enable templates to generate repetitive code structures based on model collections.
Combine MTL’s iteration constructs with AQL’s filtering and transformation operations to create sophisticated code generation patterns.
Step 1
Use AQL collections in for loops.
MTL’s [for] construct iterates over AQL collection expressions. This enables generating code for each element in model collections.
1[comment encoding = UTF-8 /]2[module CollectionLoops('http://www.example.org/webapp')]34[comment]5 Collection Iteration with AQL in MTL67 This template demonstrates using AQL collections within8 MTL's [for] loops for iterative code generation.910 The for loop iterates over AQL collection expressions,11 generating output for each element.12[/comment]1314[template main(app : WebApp)]15[file ('collection-loops.txt', 'overwrite', 'UTF-8')]16Collection Iteration with AQL17=============================1819Application: [app.name/]2021[comment ================================================================ /]22[comment BASIC FOR LOOP /]23[comment ================================================================ /]24251. Basic For Loop26-----------------27[comment]28 [for (var : Type | collection)]29 Iterates over each element in the collection.30 The variable 'var' represents the current element.31[/comment]3233All pages:34[for (page : Page | app.pages)]35- [page.name/]36[/for]3738All entities:39[for (entity : Entity | app.entities)]40- [entity.name/]41[/for]4243[comment ================================================================ /]44[comment NESTED FOR LOOPS /]45[comment ================================================================ /]46472. Nested For Loops48-------------------49[comment]50 Nest for loops to iterate through hierarchical data.51 Inner loops can access outer loop variables.52[/comment]5354Entity attribute listing:55[for (entity : Entity | app.entities)]56[entity.name/]:57[for (attr : Attribute | entity.attributes)]58 - [attr.name/]: [attr.dataType/]59[/for]6061[/for]6263Page component listing:64[for (page : Page | app.pages)]65[page.name/]:66[for (comp : Component | page.components)]67 - [comp.name/]68[/for]6970[/for]7172[comment ================================================================ /]73[comment FOR LOOPS WITH SEPARATORS /]74[comment ================================================================ /]75763. For Loops with Separators77----------------------------78[comment]79 Use [separator] to add content between elements80 (but not after the last element).81[/comment]8283Entity names (comma-separated): [for (entity : Entity | app.entities) separator(', ')][entity.name/][/for]8485Page routes (pipe-separated): [for (page : Page | app.pages) separator(' | ')][page.route/][/for]8687Attribute types: [for (attr : Attribute | app.entities->first().attributes) separator(', ')][attr.name/]:[attr.dataType/][/for]8889[comment ================================================================ /]90[comment FOR LOOPS WITH INDEX /]91[comment ================================================================ /]92934. For Loops with Index94-----------------------95[comment]96 Use i() to get the current iteration index (1-based).97 Useful for numbering or conditional logic.98[/comment]99100Numbered page list:101[for (page : Page | app.pages)]102[i/]. [page.name/] ([page.route/])103[/for]104105Numbered entity list:106[for (entity : Entity | app.entities)]107[i/]. [entity.name/]108[/for]109110[comment ================================================================ /]111[comment FOR LOOPS WITH BEFORE/AFTER /]112[comment ================================================================ /]1131145. For Loops with Before/After115------------------------------116[comment]117 [before] executes once before the loop if collection is non-empty.118 [after] executes once after the loop if collection is non-empty.119[/comment]120121[for (entity : Entity | app.entities)]122[before]123=== Entity List Start ===124[/before]125* [entity.name/]126[after]127=== Entity List End ===128[/after]129[/for]130131[comment ================================================================ /]132[comment DEEPLY NESTED LOOPS /]133[comment ================================================================ /]1341356. Deeply Nested Loops136----------------------137[comment]138 Navigate through multiple levels of containment139 using nested for loops.140[/comment]141142Complete form field analysis:143[for (page : Page | app.pages)]144[for (comp : Component | page.components->select(c | c.oclIsTypeOf(Form)))]145[let form = comp.oclAsType(Form)]146[page.name/] > [form.name/]:147[for (field : Field | form.fields)]148 [i/]. [field.name/] ([field.fieldType/])149[if (field.isRequired)]150 * Required151[/if]152[if (field.placeholder <> null and field.placeholder.size() > 0)]153 * Placeholder: "[field.placeholder/]"154[/if]155[/for]156[/let]157[/for]158[/for]159160[/file]161[/template]Step 2
Filter collections before iteration.
Apply AQL filtering operations within for loop expressions. Generate code only for elements that meet specific criteria.
1[comment encoding = UTF-8 /]2[module FilteredLoops('http://www.example.org/webapp')]34[comment]5 Filtered Collection Iteration in MTL67 This template demonstrates filtering collections8 within for loop expressions using AQL's select9 and reject operations.1011 Filtering before iteration generates code only12 for elements that meet specific criteria.13[/comment]1415[template main(app : WebApp)]16[file ('filtered-loops.txt', 'overwrite', 'UTF-8')]17Filtered Collection Iteration18=============================1920Application: [app.name/]2122[comment ================================================================ /]23[comment SELECT IN FOR LOOPS /]24[comment ================================================================ /]25261. Select in For Loops27----------------------28[comment]29 Use ->select(condition) to filter collections30 before iterating over them.31[/comment]3233Protected pages only:34[for (page : Page | app.pages->select(p | p.requiresAuth))]35- [page.name/] ([page.route/]) - requires authentication36[/for]3738Public pages only:39[for (page : Page | app.pages->select(p | not p.requiresAuth))]40- [page.name/] ([page.route/]) - public access41[/for]4243[comment ================================================================ /]44[comment REJECT IN FOR LOOPS /]45[comment ================================================================ /]46472. Reject in For Loops48----------------------49[comment]50 Use ->reject(condition) to exclude elements51 that match the condition.52[/comment]5354Non-primary-key attributes per entity:55[for (entity : Entity | app.entities)]56[entity.name/]:57[for (attr : Attribute | entity.attributes->reject(a | a.isPrimaryKey))]58 - [attr.name/]: [attr.dataType/]59[/for]6061[/for]6263[comment ================================================================ /]64[comment MULTIPLE CONDITIONS /]65[comment ================================================================ /]66673. Multiple Filter Conditions68-----------------------------69[comment]70 Combine multiple conditions with 'and' / 'or'71 for sophisticated filtering.72[/comment]7374Required string attributes:75[for (entity : Entity | app.entities)]76[let reqStrings = entity.attributes->select(a | a.dataType = DataType::string and not a.isNullable)]77[if (reqStrings->notEmpty())]78[entity.name/]:79[for (attr : Attribute | reqStrings)]80 - [attr.name/] (required string, max: [if (attr.maxLength > 0)][attr.maxLength/][else]unlimited[/if])81[/for]82[/if]83[/let]84[/for]8586[comment ================================================================ /]87[comment FILTERING BY TYPE /]88[comment ================================================================ /]89904. Filtering by Type91--------------------92[comment]93 Use oclIsTypeOf() and oclIsKindOf() to filter94 collections by element type.95[/comment]9697Forms in the application:98[for (page : Page | app.pages)]99[let forms = page.components->select(c | c.oclIsTypeOf(Form))]100[if (forms->notEmpty())]101[page.name/]:102[for (comp : Component | forms)]103 - [comp.name/] (action: [comp.oclAsType(Form).action/])104[/for]105[/if]106[/let]107[/for]108109DataTables in the application:110[for (page : Page | app.pages)]111[let tables = page.components->select(c | c.oclIsTypeOf(DataTable))]112[if (tables->notEmpty())]113[page.name/]:114[for (comp : Component | tables)]115 - [comp.name/] (rows: [comp.oclAsType(DataTable).pageSize/])116[/for]117[/if]118[/let]119[/for]120121[comment ================================================================ /]122[comment CHAINED FILTERING /]123[comment ================================================================ /]1241255. Chained Filtering126--------------------127[comment]128 Chain multiple select/reject operations for129 multi-step filtering.130[/comment]131132Non-PK, non-nullable attributes with max length set:133[for (entity : Entity | app.entities)]134[let filtered = entity.attributes135 ->reject(a | a.isPrimaryKey)136 ->select(a | not a.isNullable)137 ->select(a | a.maxLength > 0)]138[if (filtered->notEmpty())]139[entity.name/]:140[for (attr : Attribute | filtered)]141 - [attr.name/] (max: [attr.maxLength/])142[/for]143[/if]144[/let]145[/for]146147[comment ================================================================ /]148[comment STRING-BASED FILTERING /]149[comment ================================================================ /]1501516. String-Based Filtering152-------------------------153[comment]154 Use string operations in filter conditions155 for name-based or pattern matching.156[/comment]157158Attributes containing 'Date' in name:159[for (entity : Entity | app.entities)]160[let dateAttrs = entity.attributes->select(a | a.name.contains('Date') or a.name.contains('date'))]161[if (dateAttrs->notEmpty())]162[entity.name/]:163[for (attr : Attribute | dateAttrs)]164 - [attr.name/]: [attr.dataType/]165[/for]166[/if]167[/let]168[/for]169170External stylesheets:171[for (style : Stylesheet | app.stylesheets->select(s | s.isExternal))]172- [style.name/]: [style.path/]173[/for]174175Internal stylesheets:176[for (style : Stylesheet | app.stylesheets->select(s | not s.isExternal))]177- [style.name/]: [style.path/]178[/for]179180[/file]181[/template]Step 3
Transform collections with collect.
Use AQL’s collect operation to transform collections before iteration. This enables sophisticated data reshaping within templates.
1[comment encoding = UTF-8 /]2[module CollectTemplate('http://www.example.org/webapp')]34[comment]5 Collection Transformation with Collect in MTL67 This template demonstrates using AQL's collect operation8 to transform collections before iteration or output.910 Collect maps each element to a new value using an11 expression, similar to map() in functional programming.12[/comment]1314[template main(app : WebApp)]15[file ('collect-transform.txt', 'overwrite', 'UTF-8')]16Collection Transformation with Collect17======================================1819Application: [app.name/]2021[comment ================================================================ /]22[comment BASIC COLLECT /]23[comment ================================================================ /]24251. Basic Collect - Extract Properties26-------------------------------------27[comment]28 Use ->collect(expr) to extract a single property29 from each element, creating a collection of values.30[/comment]3132All page names: [app.pages->collect(p | p.name)->sep(', ')/]3334All page routes: [app.pages->collect(p | p.route)->sep(', ')/]3536All entity table names: [app.entities->collect(e | e.tableName)->sep(', ')/]3738[comment ================================================================ /]39[comment COLLECT WITH TRANSFORMATION /]40[comment ================================================================ /]41422. Collect with Transformation43------------------------------44[comment]45 Apply transformations within collect expressions46 to modify the extracted values.47[/comment]4849Entity names (uppercase): [app.entities->collect(e | e.name.toUpperCase())->sep(', ')/]5051Page routes (with base URL): [app.pages->collect(p | app.baseUrl + p.route)->sep('\n')/]5253[comment ================================================================ /]54[comment COLLECT AND ITERATE /]55[comment ================================================================ /]56573. Collect Then Iterate58-----------------------59[comment]60 Collect values first, then iterate over the61 resulting collection.62[/comment]6364All attribute names across entities:65[let allAttrNames = app.entities->collect(e | e.attributes)->flatten()->collect(a | a.name)]66[for (name : String | allAttrNames->asSet())]67- [name/]68[/for]69[/let]7071[comment ================================================================ /]72[comment NESTED COLLECT WITH FLATTEN /]73[comment ================================================================ /]74754. Nested Collect with Flatten76------------------------------77[comment]78 When collecting collections, use flatten to79 merge nested collections into a single level.80[/comment]8182All attributes (flattened from entities):83[for (attr : Attribute | app.entities->collect(e | e.attributes)->flatten())]84- [attr.name/] ([attr.dataType/])85[/for]8687All form fields (flattened from pages/forms):88[let allFields = app.pages89 ->collect(p | p.components->select(c | c.oclIsTypeOf(Form)))90 ->flatten()91 ->collect(c | c.oclAsType(Form).fields)92 ->flatten()]93[for (field : Field | allFields)]94- [field.name/] ([field.fieldType/])95[/for]96[/let]9798[comment ================================================================ /]99[comment COLLECT FOR STATISTICS /]100[comment ================================================================ /]1011025. Collect for Statistics103-------------------------104[comment]105 Use collect to extract numeric values for106 statistical operations like sum, min, max.107[/comment]108109Statistics:110- Total pages: [app.pages->size()/]111- Total entities: [app.entities->size()/]112- Total attributes: [app.entities->collect(e | e.attributes->size())->sum()/]113- Total relationships: [app.entities->collect(e | e.relationships->size())->sum()/]114- Average attributes per entity: [app.entities->collect(e | e.attributes->size())->sum() / app.entities->size()/]115116DataTable page sizes:117[let pageSizes = app.pages118 ->collect(p | p.components->select(c | c.oclIsTypeOf(DataTable)))119 ->flatten()120 ->collect(c | c.oclAsType(DataTable).pageSize)]121- Configured tables: [pageSizes->size()/]122[if (pageSizes->notEmpty())]123- Total rows visible: [pageSizes->sum()/]124- Smallest page size: [pageSizes->min()/]125- Largest page size: [pageSizes->max()/]126[/if]127[/let]128129[comment ================================================================ /]130[comment COLLECT WITH CONDITIONAL /]131[comment ================================================================ /]1321336. Collect with Conditional Expression134--------------------------------------135[comment]136 Use if-then-else within collect to conditionally137 transform elements.138[/comment]139140Attribute nullability labels:141[for (entity : Entity | app.entities)]142[entity.name/]:143[let labels = entity.attributes->collect(a |144 a.name + ': ' + if a.isNullable then 'optional' else 'required' endif)]145[for (label : String | labels)]146 [label/]147[/for]148[/let]149[/for]150151[/file]152[/template]Step 4
Generate complex structures from collections.
Run templates with collection operations to see how AQL queries shape the generated code structure. Collections drive code organisation.
1# Collection Operations Output Examples2# This script demonstrates running MTL templates with collection operations34# Run the collection loops template5swift-mtl generate \6 --template CollectionLoops.mtl \7 --model webapp-model.xmi \8 --metamodel WebApp.ecore \9 --output ./generated1011echo "Generated: collection-loops.txt"1213# Run the filtered loops template14swift-mtl generate \15 --template FilteredLoops.mtl \16 --model webapp-model.xmi \17 --metamodel WebApp.ecore \18 --output ./generated1920echo "Generated: filtered-loops.txt"2122# Run the collect transformation template23swift-mtl generate \24 --template CollectTransform.mtl \25 --model webapp-model.xmi \26 --metamodel WebApp.ecore \27 --output ./generated2829echo "Generated: collect-transform.txt"3031# Example output from filtered-loops.txt:32# -----------------------------------------33# Filtered Collection Iteration34# =============================35#36# Application: TaskManager37#38# Protected pages only:39# - Dashboard (/) - requires authentication40# - TaskList (/tasks) - requires authentication41# - Projects (/projects) - requires authentication42# - NewProject (/projects/new) - requires authentication43# - Profile (/profile) - requires authentication44#45# Public pages only:46# - Login (/login) - public access47# - Register (/register) - public access48# -----------------------------------------4950# Example output from collect-transform.txt:51# -----------------------------------------52# Collection Transformation with Collect53# ======================================54#55# All page names: Dashboard, TaskList, Projects, NewProject, Profile, Login, Register56#57# All entity table names: users, tasks, projects, comments58#59# Statistics:60# - Total pages: 761# - Total entities: 462# - Total attributes: 2463# - Total relationships: 964# - Average attributes per entity: 665# -----------------------------------------6667# View generated output68echo ""69echo "=== Collection Loops Output ==="70cat ./generated/collection-loops.txt | head -407172echo ""73echo "=== Filtered Loops Output ==="74cat ./generated/filtered-loops.txt | head -407576echo ""77echo "=== Collect Transform Output ==="78cat ./generated/collect-transform.txt | head -40Section 4
AQL’s boolean expressions integrate with MTL’s conditional statements to create adaptive templates. Templates can generate different code based on model properties and relationships.
This enables templates to respond intelligently to model variations, generating appropriate code for different scenarios.
Step 1
Use AQL boolean expressions in conditions.
MTL’s [if] statements use AQL boolean expressions as conditions. This enables templates to make decisions based on model content.
1[comment encoding = UTF-8 /]2[module ConditionalTemplate('http://www.example.org/webapp')]34[comment]5 Conditional Logic with AQL in MTL Templates67 This template demonstrates using AQL boolean expressions8 within MTL's [if] statements for conditional generation.910 Conditional logic enables templates to generate different11 output based on model properties and structure.12[/comment]1314[template main(app : WebApp)]15[file ('conditional-logic.txt', 'overwrite', 'UTF-8')]16Conditional Logic with AQL Expressions17======================================1819Application: [app.name/]2021[comment ================================================================ /]22[comment SIMPLE BOOLEAN CONDITIONS /]23[comment ================================================================ /]24251. Simple Boolean Conditions26----------------------------27[comment]28 Use boolean properties directly in if conditions.29 The condition is true when the property is true.30[/comment]3132Page access levels:33[for (page : Page | app.pages)]34- [page.name/]: [if (page.requiresAuth)]Protected[else]Public[/if]35[/for]3637[comment ================================================================ /]38[comment COMPARISON CONDITIONS /]39[comment ================================================================ /]40412. Comparison Conditions42------------------------43[comment]44 Use comparison operators: =, <>, <, >, <=, >=45 for numeric and string comparisons.46[/comment]4748Entity complexity analysis:49[for (entity : Entity | app.entities)]50[let attrCount = entity.attributes->size()]51- [entity.name/]: [attrCount/] attributes - [if (attrCount <= 3)]Simple[elseif (attrCount <= 6)]Medium[else]Complex[/if]52[/let]53[/for]5455[comment ================================================================ /]56[comment STRING CONDITIONS /]57[comment ================================================================ /]58593. String Conditions60--------------------61[comment]62 Use string operations in conditions:63 .startsWith(), .endsWith(), .contains(), etc.64[/comment]6566Route categorisation:67[for (page : Page | app.pages)]68- [page.route/]: [if (page.route = '/')]Home[elseif (page.route.startsWith('/api'))]API[elseif (page.route.contains('/new'))]Creation[else]Standard[/if]69[/for]7071[comment ================================================================ /]72[comment COLLECTION CONDITIONS /]73[comment ================================================================ /]74754. Collection Conditions76------------------------77[comment]78 Use collection operations that return booleans:79 ->isEmpty(), ->notEmpty(), ->includes(), etc.80[/comment]8182Entity relationship status:83[for (entity : Entity | app.entities)]84- [entity.name/]: [if (entity.relationships->isEmpty())]Standalone[else]Has [entity.relationships->size()/] relationship(s)[/if]85[/for]8687Page component status:88[for (page : Page | app.pages)]89- [page.name/]: [if (page.components->notEmpty())][page.components->size()/] component(s)[else]Empty page[/if]90[/for]9192[comment ================================================================ /]93[comment TYPE CONDITIONS /]94[comment ================================================================ /]95965. Type Conditions97------------------98[comment]99 Use oclIsTypeOf() and oclIsKindOf() to check100 element types for type-based conditional output.101[/comment]102103Component classification:104[for (page : Page | app.pages)]105[page.name/]:106[for (comp : Component | page.components)]107 - [comp.name/]: [if (comp.oclIsTypeOf(Form))]Form[elseif (comp.oclIsTypeOf(DataTable))]Data Table[elseif (comp.oclIsTypeOf(Navigation))]Navigation[else]Component[/if]108[/for]109110[/for]111112[comment ================================================================ /]113[comment ENUMERATION CONDITIONS /]114[comment ================================================================ /]1151166. Enumeration Conditions117-------------------------118[comment]119 Compare enumeration values using = and <>.120 Reference enum literals with EnumType::literal.121[/comment]122123Attribute type classification:124[for (entity : Entity | app.entities)]125[entity.name/]:126[for (attr : Attribute | entity.attributes)]127 - [attr.name/]: [if (attr.dataType = DataType::string or attr.dataType = DataType::text)]Text[elseif (attr.dataType = DataType::integer or attr.dataType = DataType::decimal)]Numeric[elseif (attr.dataType = DataType::date or attr.dataType = DataType::datetime)]Temporal[elseif (attr.dataType = DataType::boolean)]Boolean[else]Other[/if]128[/for]129130[/for]131132[/file]133[/template]Step 2
Combine multiple conditions.
Use AQL’s and, or, and not operators to create complex conditional logic. Templates can respond to sophisticated model patterns.
1[comment encoding = UTF-8 /]2[module ComplexConditions('http://www.example.org/webapp')]34[comment]5 Complex Conditional Logic in MTL Templates67 This template demonstrates combining multiple AQL8 conditions using 'and', 'or', and 'not' operators.910 Complex conditions enable sophisticated decision-making11 based on multiple model properties.12[/comment]1314[template main(app : WebApp)]15[file ('complex-conditions.txt', 'overwrite', 'UTF-8')]16Complex Conditional Logic with AQL17==================================1819Application: [app.name/]2021[comment ================================================================ /]22[comment AND OPERATOR /]23[comment ================================================================ /]24251. AND Operator - All Conditions Must Be True26---------------------------------------------27[comment]28 Use 'and' to require multiple conditions.29 All conditions must be true for the block to execute.30[/comment]3132Required string attributes (not null AND string type AND not nullable):33[for (entity : Entity | app.entities)]34[entity.name/]:35[for (attr : Attribute | entity.attributes)]36[if (attr.dataType = DataType::string and not attr.isNullable and not attr.isPrimaryKey)]37 - [attr.name/] (required string)38[/if]39[/for]4041[/for]4243[comment ================================================================ /]44[comment OR OPERATOR /]45[comment ================================================================ /]46472. OR Operator - Any Condition Can Be True48------------------------------------------49[comment]50 Use 'or' to allow alternative conditions.51 At least one condition must be true.52[/comment]5354Temporal attributes (date OR datetime):55[for (entity : Entity | app.entities)]56[entity.name/]:57[for (attr : Attribute | entity.attributes)]58[if (attr.dataType = DataType::date or attr.dataType = DataType::datetime)]59 - [attr.name/]: [attr.dataType/]60[/if]61[/for]6263[/for]6465Authentication-related pages (login OR register route):66[for (page : Page | app.pages)]67[if (page.route = '/login' or page.route = '/register')]68- [page.name/] ([page.route/]) - Authentication page69[/if]70[/for]7172[comment ================================================================ /]73[comment NOT OPERATOR /]74[comment ================================================================ /]75763. NOT Operator - Negating Conditions77-------------------------------------78[comment]79 Use 'not' to negate a condition.80 The block executes when the condition is false.81[/comment]8283Non-primary-key attributes:84[for (entity : Entity | app.entities)]85[entity.name/]:86[for (attr : Attribute | entity.attributes)]87[if (not attr.isPrimaryKey)]88 - [attr.name/]89[/if]90[/for]9192[/for]9394[comment ================================================================ /]95[comment COMBINED OPERATORS /]96[comment ================================================================ /]97984. Combined Operators99---------------------100[comment]101 Combine and, or, not for sophisticated logic.102 Use parentheses to control precedence.103[/comment]104105Complex attribute filter (string type AND (nullable OR has default)):106[for (entity : Entity | app.entities)]107[entity.name/]:108[for (attr : Attribute | entity.attributes)]109[if (attr.dataType = DataType::string and (attr.isNullable or (attr.defaultValue <> null and attr.defaultValue.size() > 0)))]110 - [attr.name/]: optional string111[/if]112[/for]113114[/for]115116Non-trivial pages (protected AND has components AND has links):117[for (page : Page | app.pages)]118[if (page.requiresAuth and page.components->notEmpty() and page.linkedPages->notEmpty())]119- [page.name/] - full-featured protected page120[/if]121[/for]122123[comment ================================================================ /]124[comment NESTED CONDITIONALS /]125[comment ================================================================ /]1261275. Nested Conditionals128----------------------129[comment]130 Nest if statements for multi-level decisions.131 Inner conditions are evaluated only when outer is true.132[/comment]133134Page security analysis:135[for (page : Page | app.pages)]136[page.name/]:137[if (page.requiresAuth)]138 Access: Protected139 [if (page.components->exists(c | c.oclIsTypeOf(Form)))]140 Type: Authenticated data entry141 [if (page.components->select(c | c.oclIsTypeOf(Form))->size() > 1)]142 Note: Multiple forms present143 [/if]144 [elseif (page.components->exists(c | c.oclIsTypeOf(DataTable)))]145 Type: Authenticated data viewing146 [else]147 Type: Authenticated information148 [/if]149[else]150 Access: Public151 [if (page.route.contains('login') or page.route.contains('register'))]152 Type: Authentication flow153 [else]154 Type: Public information155 [/if]156[/if]157158[/for]159160[comment ================================================================ /]161[comment CONDITIONAL WITH COMPUTATION /]162[comment ================================================================ /]1631646. Conditional with Computation165-------------------------------166[comment]167 Use computed values in conditions.168 Let bindings help make complex conditions readable.169[/comment]170171Entity analysis:172[for (entity : Entity | app.entities)]173[let attrCount = entity.attributes->size()]174[let relCount = entity.relationships->size()]175[let hasTimestamps = entity.attributes->exists(a | a.name.endsWith('At') or a.name.contains('Date'))]176[entity.name/]:177[if (attrCount > 5 and relCount > 1)]178 Category: Core entity (many attributes and relationships)179[elseif (attrCount > 3 or relCount > 0)]180 Category: Standard entity181[else]182 Category: Simple entity183[/if]184[if (hasTimestamps)]185 Features: Timestamped186[/if]187[/let]188[/let]189[/let]190191[/for]192193[/file]194[/template]Step 3
Use quantifiers in template conditions.
Apply AQL’s exists and forAll operations in template conditions. Generate code based on the existence or universality of model patterns.
1[comment encoding = UTF-8 /]2[module QuantifierConditions('http://www.example.org/webapp')]34[comment]5 Quantifier Operations in Conditional Generation67 This template demonstrates using AQL's quantifier8 operations (exists, forAll) within conditional statements.910 Quantifiers test whether conditions hold across11 collection elements - essential for validation logic.12[/comment]1314[template main(app : WebApp)]15[file ('quantifier-conditions.txt', 'overwrite', 'UTF-8')]16Quantifier Operations in Conditions17===================================1819Application: [app.name/]2021[comment ================================================================ /]22[comment EXISTS OPERATION /]23[comment ================================================================ /]24251. Exists - At Least One Element Matches26----------------------------------------27[comment]28 ->exists(condition) returns true if ANY element29 in the collection satisfies the condition.30[/comment]3132[if (app.pages->exists(p | p.requiresAuth))]33This application has protected pages requiring authentication.34[else]35All pages are publicly accessible.36[/if]3738[if (app.entities->exists(e | e.relationships->notEmpty()))]39The data model includes entity relationships.40[/if]4142[if (app.stylesheets->exists(s | s.isExternal))]43External stylesheets (CDN resources) are configured.44[/if]4546[comment ================================================================ /]47[comment FORALL OPERATION /]48[comment ================================================================ /]49502. ForAll - All Elements Match51------------------------------52[comment]53 ->forAll(condition) returns true if ALL elements54 satisfy the condition (or collection is empty).55[/comment]5657[if (app.entities->forAll(e | e.attributes->exists(a | a.isPrimaryKey)))]58[OK] All entities have primary keys defined.59[else]60[WARNING] Some entities lack primary keys.61[/if]6263[if (app.pages->forAll(p | p.title <> null and p.title.size() > 0))]64[OK] All pages have titles set.65[else]66[WARNING] Some pages are missing titles.67[/if]6869[if (app.entities->forAll(e | e.tableName <> null and e.tableName.size() > 0))]70[OK] All entities have table names defined.71[else]72[WARNING] Some entities lack table name configuration.73[/if]7475[comment ================================================================ /]76[comment EXISTS IN LOOPS /]77[comment ================================================================ /]78793. Exists Within Iteration80--------------------------81[comment]82 Use exists to conditionally include content83 based on nested collection properties.84[/comment]8586Entity relationship status:87[for (entity : Entity | app.entities)]88[entity.name/]:89[if (entity.relationships->exists(r | r.relationType = RelationType::oneToMany))]90 - Has one-to-many relationships91[/if]92[if (entity.relationships->exists(r | r.relationType = RelationType::manyToMany))]93 - Has many-to-many relationships94[/if]95[if (entity.relationships->exists(r | r.relationType = RelationType::manyToOne))]96 - Has many-to-one relationships97[/if]98[if (not entity.relationships->exists(r | true))]99 - No relationships defined100[/if]101102[/for]103104[comment ================================================================ /]105[comment FORALL IN LOOPS /]106[comment ================================================================ /]1071084. ForAll Within Iteration109--------------------------110[comment]111 Use forAll to validate that all nested elements112 meet certain criteria.113[/comment]114115Entity validation report:116[for (entity : Entity | app.entities)]117[entity.name/]:118[if (entity.attributes->forAll(a | a.name <> null and a.name.size() > 0))]119 [PASS] All attributes are named120[else]121 [FAIL] Some attributes lack names122[/if]123[if (entity.attributes->forAll(a | a.dataType <> null))]124 [PASS] All attributes have data types125[else]126 [FAIL] Some attributes lack data types127[/if]128[if (entity.attributes->reject(a | a.isPrimaryKey)->forAll(a | a.isNullable or (a.defaultValue <> null and a.defaultValue.size() > 0)))]129 [PASS] All non-PK attributes are nullable or have defaults130[else]131 [INFO] Some non-PK attributes are required without defaults132[/if]133134[/for]135136[comment ================================================================ /]137[comment COMBINED QUANTIFIERS /]138[comment ================================================================ /]1391405. Combined Quantifier Patterns141-------------------------------142[comment]143 Combine exists and forAll for comprehensive144 validation and conditional logic.145[/comment]146147Application validation summary:148149Schema validation:150[if (app.entities->forAll(e | e.attributes->exists(a | a.isPrimaryKey)))]151 [PASS] Every entity has a primary key152[else]153 [FAIL] Not all entities have primary keys154[/if]155156Security validation:157[if (app.pages->exists(p | not p.requiresAuth) and app.pages->exists(p | p.requiresAuth))]158 [INFO] Mixed access - both public and protected pages159[elseif (app.pages->forAll(p | p.requiresAuth))]160 [INFO] Fully protected - all pages require authentication161[else]162 [INFO] Fully public - no authentication required163[/if]164165UI completeness:166[if (app.pages->forAll(p | p.components->notEmpty()))]167 [PASS] All pages have components168[else]169 [WARN] Some pages have no components170[/if]171172[comment ================================================================ /]173[comment NESTED QUANTIFIERS /]174[comment ================================================================ /]1751766. Nested Quantifier Expressions177--------------------------------178[comment]179 Quantifiers can be nested for complex validation.180 Keep nesting shallow for readability.181[/comment]182183Deep validation:184[if (app.pages->forAll(p | p.components->forAll(c | c.name <> null)))]185 [PASS] All components on all pages are named186[else]187 [FAIL] Some components lack names188[/if]189190[if (app.pages->exists(p | p.components->exists(c | c.oclIsTypeOf(Form))))]191 [INFO] Application includes data entry forms192[/if]193194Form completeness:195[for (page : Page | app.pages)]196[let forms = page.components->select(c | c.oclIsTypeOf(Form))->collect(c | c.oclAsType(Form))]197[if (forms->notEmpty())]198[page.name/]:199[if (forms->forAll(f | f.fields->notEmpty()))]200 [PASS] All forms have fields201[else]202 [WARN] Some forms are empty203[/if]204[if (forms->forAll(f | f.boundEntity <> null))]205 [PASS] All forms are bound to entities206[else]207 [INFO] Some forms are not bound to entities208[/if]209[/if]210[/let]211[/for]212213[/file]214[/template]Step 4
Generate adaptive code structures.
Run templates with conditional logic to see how AQL expressions create adaptive code generation. The same template generates different code for different models.
1# Adaptive Code Generation Output Examples2# This script demonstrates running MTL templates with conditional logic34# Run the conditional template5swift-mtl generate \6 --template ConditionalTemplate.mtl \7 --model webapp-model.xmi \8 --metamodel WebApp.ecore \9 --output ./generated1011echo "Generated: conditional-logic.txt"1213# Run the complex conditions template14swift-mtl generate \15 --template ComplexConditions.mtl \16 --model webapp-model.xmi \17 --metamodel WebApp.ecore \18 --output ./generated1920echo "Generated: complex-conditions.txt"2122# Run the quantifier conditions template23swift-mtl generate \24 --template QuantifierConditions.mtl \25 --model webapp-model.xmi \26 --metamodel WebApp.ecore \27 --output ./generated2829echo "Generated: quantifier-conditions.txt"3031# Example output from conditional-logic.txt:32# -----------------------------------------33# Conditional Logic with AQL Expressions34# ======================================35#36# Application: TaskManager37#38# Page access levels:39# - Dashboard: Protected40# - TaskList: Protected41# - Projects: Protected42# - NewProject: Protected43# - Profile: Protected44# - Login: Public45# - Register: Public46#47# Entity complexity analysis:48# - User: 6 attributes - Medium49# - Task: 7 attributes - Complex50# - Project: 6 attributes - Medium51# - Comment: 3 attributes - Simple52# -----------------------------------------5354# Example output from quantifier-conditions.txt:55# -----------------------------------------56# Application validation summary:57#58# Schema validation:59# [PASS] Every entity has a primary key60#61# Security validation:62# [INFO] Mixed access - both public and protected pages63#64# UI completeness:65# [PASS] All pages have components66# -----------------------------------------6768# View generated output69echo ""70echo "=== Conditional Logic Output ==="71cat ./generated/conditional-logic.txt | head -407273echo ""74echo "=== Complex Conditions Output ==="75cat ./generated/complex-conditions.txt | head -407677echo ""78echo "=== Quantifier Conditions Output ==="79cat ./generated/quantifier-conditions.txt | head -50Section 5
Advanced patterns combine AQL’s full querying power with MTL’s template features. These patterns enable sophisticated code generation scenarios and complex model analysis.
Master these patterns to create professional-grade code generators that handle real-world modeling scenarios.
Step 1
Create reusable AQL expressions with let bindings.
Use MTL’s [let] construct to bind complex AQL expressions to variables. This improves template readability and avoids repeated computation.
1[comment encoding = UTF-8 /]2[module LetTemplate('http://www.example.org/webapp')]34[comment]5 Let Bindings in MTL Templates67 This template demonstrates using MTL's [let] construct8 to bind complex AQL expressions to named variables.910 Let bindings improve readability, avoid repeated11 computation, and make templates more maintainable.12[/comment]1314[template main(app : WebApp)]15[file ('let-bindings.txt', 'overwrite', 'UTF-8')]16Let Bindings in MTL Templates17=============================1819Application: [app.name/]2021[comment ================================================================ /]22[comment BASIC LET BINDINGS /]23[comment ================================================================ /]24251. Basic Let Bindings26---------------------27[comment]28 [let varName = expression]29 ... use varName ...30 [/let]3132 The variable is only in scope within the let block.33[/comment]3435[let pageCount = app.pages->size()]36[let entityCount = app.entities->size()]37[let stylesheetCount = app.stylesheets->size()]38Application statistics:39- Pages: [pageCount/]40- Entities: [entityCount/]41- Stylesheets: [stylesheetCount/]42- Total elements: [pageCount + entityCount + stylesheetCount/]43[/let]44[/let]45[/let]4647[comment ================================================================ /]48[comment LET FOR FILTERED COLLECTIONS /]49[comment ================================================================ /]50512. Let for Filtered Collections52-------------------------------53[comment]54 Bind filtered collections to avoid repeating55 the filter expression multiple times.56[/comment]5758[let protectedPages = app.pages->select(p | p.requiresAuth)]59[let publicPages = app.pages->reject(p | p.requiresAuth)]60Access configuration:61- Protected pages: [protectedPages->size()/]62[for (page : Page | protectedPages)]63 - [page.name/] ([page.route/])64[/for]65- Public pages: [publicPages->size()/]66[for (page : Page | publicPages)]67 - [page.name/] ([page.route/])68[/for]69[/let]70[/let]7172[comment ================================================================ /]73[comment NESTED LET BINDINGS /]74[comment ================================================================ /]75763. Nested Let Bindings77----------------------78[comment]79 Let bindings can be nested. Inner bindings can80 reference outer bindings.81[/comment]8283[for (entity : Entity | app.entities)]84[let allAttrs = entity.attributes]85[let pkAttrs = allAttrs->select(a | a.isPrimaryKey)]86[let nonPkAttrs = allAttrs->reject(a | a.isPrimaryKey)]87[let requiredAttrs = nonPkAttrs->select(a | not a.isNullable)]88[let optionalAttrs = nonPkAttrs->select(a | a.isNullable)]8990[entity.name/] breakdown:91 Total: [allAttrs->size()/]92 Primary key(s): [pkAttrs->size()/]93 Required: [requiredAttrs->size()/]94 Optional: [optionalAttrs->size()/]95[/let]96[/let]97[/let]98[/let]99[/let]100[/for]101102[comment ================================================================ /]103[comment LET FOR COMPUTED VALUES /]104[comment ================================================================ /]1051064. Let for Computed Values107--------------------------108[comment]109 Use let for computed strings, formatted values,110 or any expression result to be reused.111[/comment]112113[for (page : Page | app.pages)]114[let componentCount = page.components->size()]115[let hasNav = page.components->exists(c | c.oclIsTypeOf(Navigation))]116[let hasForms = page.components->exists(c | c.oclIsTypeOf(Form))]117[let hasTables = page.components->exists(c | c.oclIsTypeOf(DataTable))]118[let features = if hasNav then 'Nav ' else '' endif + if hasForms then 'Forms ' else '' endif + if hasTables then 'Tables' else '' endif]119120[page.name/]:121 Components: [componentCount/]122 Features: [if (features.size() > 0)][features/][else]None[/if]123[/let]124[/let]125[/let]126[/let]127[/let]128[/for]129130[comment ================================================================ /]131[comment LET FOR COMPLEX NAVIGATION /]132[comment ================================================================ /]1331345. Let for Complex Navigation135-----------------------------136[comment]137 Bind intermediate navigation results for clarity138 when dealing with long navigation chains.139[/comment]140141[for (page : Page | app.pages)]142[let forms = page.components->select(c | c.oclIsTypeOf(Form))->collect(c | c.oclAsType(Form))]143[let boundForms = forms->select(f | f.boundEntity <> null)]144[let unboundForms = forms->reject(f | f.boundEntity <> null)]145[if (forms->notEmpty())]146[page.name/] form analysis:147 Total forms: [forms->size()/]148 Bound to entities: [boundForms->size()/]149 Unbound: [unboundForms->size()/]150[for (form : Form | boundForms)]151 - [form.name/] -> [form.boundEntity.name/] ([form.fields->size()/] fields)152[/for]153[/if]154[/let]155[/let]156[/let]157[/for]158159[comment ================================================================ /]160[comment LET WITH AGGREGATIONS /]161[comment ================================================================ /]1621636. Let with Aggregations164------------------------165[comment]166 Bind aggregated values for statistics and summaries.167[/comment]168169[let totalAttrs = app.entities->collect(e | e.attributes->size())->sum()]170[let totalRels = app.entities->collect(e | e.relationships->size())->sum()]171[let avgAttrs = totalAttrs / app.entities->size()]172[let maxAttrs = app.entities->collect(e | e.attributes->size())->max()]173[let minAttrs = app.entities->collect(e | e.attributes->size())->min()]174175Data model statistics:176- Total attributes: [totalAttrs/]177- Total relationships: [totalRels/]178- Average attributes per entity: [avgAttrs/]179- Largest entity: [maxAttrs/] attributes180- Smallest entity: [minAttrs/] attributes181[/let]182[/let]183[/let]184[/let]185[/let]186187[/file]188[/template]Step 2
Build query-driven template libraries.
Create templates that serve as AQL query libraries. These templates can be imported and reused across multiple generation scenarios.
1[comment encoding = UTF-8 /]2[module QueryLibrary('http://www.example.org/webapp')]34[comment]5 Reusable AQL Query Templates67 This module demonstrates creating a library of reusable8 query templates that can be imported and invoked from9 other templates.1011 Query libraries centralise complex AQL expressions,12 promoting code reuse and maintainability.13[/comment]1415[comment ================================================================ /]16[comment QUERY TEMPLATES (HELPERS) /]17[comment ================================================================ /]1819[comment]20 Query templates return computed values.21 They encapsulate complex AQL expressions.22[/comment]2324[template public getProtectedPages(app : WebApp)]25[app.pages->select(p | p.requiresAuth)/]26[/template]2728[template public getPublicPages(app : WebApp)]29[app.pages->select(p | not p.requiresAuth)/]30[/template]3132[template public getPrimaryKeyAttributes(entity : Entity)]33[entity.attributes->select(a | a.isPrimaryKey)/]34[/template]3536[template public getRequiredAttributes(entity : Entity)]37[entity.attributes->reject(a | a.isPrimaryKey)->select(a | not a.isNullable)/]38[/template]3940[template public getOptionalAttributes(entity : Entity)]41[entity.attributes->select(a | a.isNullable)/]42[/template]4344[template public getStringAttributes(entity : Entity)]45[entity.attributes->select(a | a.dataType = DataType::string or a.dataType = DataType::text)/]46[/template]4748[template public getNumericAttributes(entity : Entity)]49[entity.attributes->select(a | a.dataType = DataType::integer or a.dataType = DataType::decimal)/]50[/template]5152[template public getDateAttributes(entity : Entity)]53[entity.attributes->select(a | a.dataType = DataType::date or a.dataType = DataType::datetime)/]54[/template]5556[template public getFormsOnPage(page : Page)]57[page.components->select(c | c.oclIsTypeOf(Form))->collect(c | c.oclAsType(Form))/]58[/template]5960[template public getTablesOnPage(page : Page)]61[page.components->select(c | c.oclIsTypeOf(DataTable))->collect(c | c.oclAsType(DataTable))/]62[/template]6364[comment ================================================================ /]65[comment FORMATTED OUTPUT TEMPLATES /]66[comment ================================================================ /]6768[comment]69 Output templates generate formatted text.70 They can be invoked from other templates.71[/comment]7273[template public formatAttributeType(attr : Attribute)]74[if (attr.dataType = DataType::string)]String[if (attr.maxLength > 0)]([attr.maxLength/])[/if][elseif (attr.dataType = DataType::integer)]Int[elseif (attr.dataType = DataType::decimal)]Decimal[elseif (attr.dataType = DataType::boolean)]Bool[elseif (attr.dataType = DataType::date)]Date[elseif (attr.dataType = DataType::datetime)]DateTime[elseif (attr.dataType = DataType::text)]Text[else][attr.dataType/][/if][/template]7576[template public formatFieldType(field : Field)]77[if (field.fieldType = FieldType::text)]text[elseif (field.fieldType = FieldType::email)]email[elseif (field.fieldType = FieldType::password)]password[elseif (field.fieldType = FieldType::number)]number[elseif (field.fieldType = FieldType::date)]date[elseif (field.fieldType = FieldType::textarea)]textarea[elseif (field.fieldType = FieldType::select)]select[elseif (field.fieldType = FieldType::checkbox)]checkbox[elseif (field.fieldType = FieldType::hidden)]hidden[else][field.fieldType/][/if][/template]7879[template public formatRelationType(rel : Relationship)]80[if (rel.relationType = RelationType::oneToOne)]1:1[elseif (rel.relationType = RelationType::oneToMany)]1:N[elseif (rel.relationType = RelationType::manyToOne)]N:1[elseif (rel.relationType = RelationType::manyToMany)]N:N[else][rel.relationType/][/if][/template]8182[comment ================================================================ /]83[comment MAIN TEMPLATE - USING THE LIBRARY /]84[comment ================================================================ /]8586[template main(app : WebApp)]87[file ('query-library-demo.txt', 'overwrite', 'UTF-8')]88Query Library Demonstration89===========================9091Application: [app.name/]9293Using Query Templates94---------------------9596Protected pages (via query template):97[for (page : Page | app.pages->select(p | p.requiresAuth))]98- [page.name/]99[/for]100101Public pages (via query template):102[for (page : Page | app.pages->select(p | not p.requiresAuth))]103- [page.name/]104[/for]105106Entity attribute breakdown (using helper queries):107[for (entity : Entity | app.entities)]108[entity.name/]:109 Primary keys: [entity.attributes->select(a | a.isPrimaryKey)->collect(a | a.name)->sep(', ')/]110 Required: [entity.attributes->reject(a | a.isPrimaryKey)->select(a | not a.isNullable)->collect(a | a.name)->sep(', ')/]111 Optional: [entity.attributes->select(a | a.isNullable)->collect(a | a.name)->sep(', ')/]112113[/for]114115Formatted attribute types:116[for (entity : Entity | app.entities)]117[entity.name/]:118[for (attr : Attribute | entity.attributes)]119 - [attr.name/]: [formatAttributeType(attr)/][if (attr.isPrimaryKey)] (PK)[/if][if (not attr.isNullable and not attr.isPrimaryKey)] (required)[/if]120[/for]121122[/for]123124Formatted relationship types:125[for (entity : Entity | app.entities)]126[if (entity.relationships->notEmpty())]127[entity.name/]:128[for (rel : Relationship | entity.relationships)]129 - [rel.name/] [formatRelationType(rel)/] [rel.targetEntity.name/]130[/for]131132[/if]133[/for]134135Forms and their fields (using helper queries):136[for (page : Page | app.pages)]137[let pageForms = page.components->select(c | c.oclIsTypeOf(Form))->collect(c | c.oclAsType(Form))]138[if (pageForms->notEmpty())]139[page.name/]:140[for (form : Form | pageForms)]141 [form.name/]:142[for (field : Field | form.fields)]143 - [field.name/]: [formatFieldType(field)/][if (field.isRequired)] (required)[/if]144[/for]145[/for]146147[/if]148[/let]149[/for]150151[/file]152[/template]Step 3
Handle cross-reference resolution.
Use AQL to navigate cross-model references and generate code that maintains referential integrity across generated artefacts.
1[comment encoding = UTF-8 /]2[module CrossReferences('http://www.example.org/webapp')]34[comment]5 Cross-Reference Resolution in MTL Templates67 This template demonstrates using AQL to navigate8 cross-model references and generate code that maintains9 referential integrity across generated artefacts.1011 Cross-references link model elements that are not12 in a containment relationship, requiring careful13 navigation and resolution.14[/comment]1516[template main(app : WebApp)]17[file ('cross-references.txt', 'overwrite', 'UTF-8')]18Cross-Reference Resolution with AQL19===================================2021Application: [app.name/]2223[comment ================================================================ /]24[comment NAVIGATING CROSS-REFERENCES /]25[comment ================================================================ /]26271. Navigating Cross-References28------------------------------29[comment]30 Cross-references connect related elements.31 Navigate them like containment references.32[/comment]3334Entity relationships (cross-references to other entities):35[for (entity : Entity | app.entities)]36[entity.name/]:37[if (entity.relationships->notEmpty())]38[for (rel : Relationship | entity.relationships)]39 - [rel.name/] -> [rel.targetEntity.name/] ([rel.relationType/])40[/for]41[else]42 (no relationships)43[/if]4445[/for]4647[comment ================================================================ /]48[comment PAGE LINK REFERENCES /]49[comment ================================================================ /]50512. Page Link References52-----------------------53[comment]54 Pages can link to other pages, creating a navigation55 graph. Follow these references to understand flow.56[/comment]5758Page navigation graph:59[for (page : Page | app.pages)]60[page.name/] -> [if (page.linkedPages->notEmpty())][page.linkedPages->collect(p | p.name)->sep(', ')/][else](no outbound links)[/if]61[/for]6263Incoming links analysis:64[for (page : Page | app.pages)]65[let incomingLinks = app.pages->select(p | p.linkedPages->includes(page))]66[page.name/] <- [if (incomingLinks->notEmpty())][incomingLinks->collect(p | p.name)->sep(', ')/][else](no incoming links)[/if]67[/let]68[/for]6970[comment ================================================================ /]71[comment FORM-ENTITY BINDINGS /]72[comment ================================================================ /]73743. Form-Entity Bindings75-----------------------76[comment]77 Forms can be bound to entities, creating cross-references78 between UI components and data models.79[/comment]8081Form-entity binding map:82[for (page : Page | app.pages)]83[for (comp : Component | page.components->select(c | c.oclIsTypeOf(Form)))]84[let form = comp.oclAsType(Form)]85[page.name/]/[form.name/]:86[if (form.boundEntity <> null)]87 Bound to: [form.boundEntity.name/]88 Entity attributes: [form.boundEntity.attributes->collect(a | a.name)->sep(', ')/]89 Form fields: [form.fields->collect(f | f.name)->sep(', ')/]90[else]91 Not bound to any entity92[/if]93[/let]94[/for]95[/for]9697[comment ================================================================ /]98[comment FIELD-ATTRIBUTE BINDINGS /]99[comment ================================================================ /]1001014. Field-Attribute Bindings102---------------------------103[comment]104 Form fields can be bound to entity attributes,105 connecting UI input to data storage.106[/comment]107108Field-attribute mapping:109[for (page : Page | app.pages)]110[for (comp : Component | page.components->select(c | c.oclIsTypeOf(Form)))]111[let form = comp.oclAsType(Form)]112[if (form.fields->exists(f | f.boundAttribute <> null))]113[page.name/]/[form.name/] field bindings:114[for (field : Field | form.fields)]115[if (field.boundAttribute <> null)]116 [field.name/] ([field.fieldType/]) -> [field.boundAttribute.name/] ([field.boundAttribute.dataType/])117[else]118 [field.name/] ([field.fieldType/]) -> (unbound)119[/if]120[/for]121122[/if]123[/let]124[/for]125[/for]126127[comment ================================================================ /]128[comment TABLE-ENTITY BINDINGS /]129[comment ================================================================ /]1301315. DataTable-Entity Bindings132----------------------------133[comment]134 DataTables bind to entities as data sources,135 and columns bind to attributes.136[/comment]137138DataTable data source mappings:139[for (page : Page | app.pages)]140[for (comp : Component | page.components->select(c | c.oclIsTypeOf(DataTable)))]141[let table = comp.oclAsType(DataTable)]142[page.name/]/[table.name/]:143[if (table.dataSource <> null)]144 Data source: [table.dataSource.name/]145 Columns:146[for (col : Column | table.columns)]147 [col.header/] -> [if (col.boundAttribute <> null)][col.boundAttribute.name/][else](unbound)[/if]148[/for]149[else]150 No data source configured151[/if]152[/let]153[/for]154[/for]155156[comment ================================================================ /]157[comment NAVIGATION TARGET REFERENCES /]158[comment ================================================================ /]1591606. Navigation Target References161-------------------------------162[comment]163 Navigation items reference target pages,164 building the application's navigation structure.165[/comment]166167Navigation structure:168[for (page : Page | app.pages)]169[for (comp : Component | page.components->select(c | c.oclIsTypeOf(Navigation)))]170[let nav = comp.oclAsType(Navigation)]171[page.name/]/[nav.name/] ([nav.navType/]):172[for (item : NavItem | nav.items)]173 [item.label/] -> [if (item.targetPage <> null)][item.targetPage.name/] ([item.targetPage.route/])[else](no target)[/if]174[for (subItem : NavItem | item.subItems)]175 [subItem.label/] -> [if (subItem.targetPage <> null)][subItem.targetPage.name/][else](no target)[/if]176[/for]177[/for]178[/let]179[/for]180[/for]181182[comment ================================================================ /]183[comment REFERENTIAL INTEGRITY CHECK /]184[comment ================================================================ /]1851867. Referential Integrity Validation187-----------------------------------188[comment]189 Validate that all cross-references point to190 valid targets within the model.191[/comment]192193Reference validation:194195Entity relationship targets:196[for (entity : Entity | app.entities)]197[for (rel : Relationship | entity.relationships)]198[if (app.entities->includes(rel.targetEntity))]199[OK] [entity.name/].[rel.name/] -> [rel.targetEntity.name/]200[else]201[ERROR] [entity.name/].[rel.name/] -> invalid target202[/if]203[/for]204[/for]205206Page link targets:207[for (page : Page | app.pages)]208[for (linked : Page | page.linkedPages)]209[if (app.pages->includes(linked))]210[OK] [page.name/] -> [linked.name/]211[else]212[ERROR] [page.name/] -> invalid page reference213[/if]214[/for]215[/for]216217[/file]218[/template]Step 4
Create comprehensive code generation pipelines.
Combine all AQL-MTL patterns to create sophisticated code generators. See how queries drive every aspect of code structure and content.
1#!/bin/bash2#3# Comprehensive Code Generation Example4# Demonstrates running MTL templates with AQL expressions5#6# This script shows how to invoke the swift-mtl tool to generate7# code from a web application model using the templates that8# demonstrate AQL expressions within MTL.9#1011set -e1213# Configuration14MODEL_FILE="webapp-instance.xmi"15METAMODEL_FILE="webapp-metamodel.ecore"16OUTPUT_DIR="./generated"1718echo "=========================================="19echo "AQL in MTL - Comprehensive Generation"20echo "=========================================="21echo ""2223# Check for required files24if [ ! -f "$MODEL_FILE" ]; then25 echo "Error: Model file '$MODEL_FILE' not found"26 exit 127fi2829if [ ! -f "$METAMODEL_FILE" ]; then30 echo "Error: Metamodel file '$METAMODEL_FILE' not found"31 exit 132fi3334# Create output directory35mkdir -p "$OUTPUT_DIR"36echo "Output directory: $OUTPUT_DIR"37echo ""3839# ============================================40# Step 1: Basic Template - Navigation Demo41# ============================================42echo "Step 1: Running basic template (navigation expressions)..."43swift-mtl generate \44 --template aql-04-step-03-basic-template.mtl \45 --model "$MODEL_FILE" \46 --metamodel "$METAMODEL_FILE" \47 --output "$OUTPUT_DIR/docs"4849echo " Generated: README.md"50echo ""5152# ============================================53# Step 2: Collection Operations Demo54# ============================================55echo "Step 2: Running collection operations template..."56swift-mtl generate \57 --template aql-04-step-05-collection-operations.mtl \58 --model "$MODEL_FILE" \59 --metamodel "$METAMODEL_FILE" \60 --output "$OUTPUT_DIR/docs"6162echo " Generated: collection-ops.txt"63echo ""6465# ============================================66# Step 3: Select and Reject Demo67# ============================================68echo "Step 3: Running select/reject template..."69swift-mtl generate \70 --template aql-04-step-06-select-and-reject.mtl \71 --model "$MODEL_FILE" \72 --metamodel "$METAMODEL_FILE" \73 --output "$OUTPUT_DIR/docs"7475echo " Generated: filtering.txt"76echo ""7778# ============================================79# Step 4: String Operations Demo80# ============================================81echo "Step 4: Running string operations template..."82swift-mtl generate \83 --template aql-04-step-10-string-operations.mtl \84 --model "$MODEL_FILE" \85 --metamodel "$METAMODEL_FILE" \86 --output "$OUTPUT_DIR/docs"8788echo " Generated: string-ops.txt"89echo ""9091# ============================================92# Step 5: Type Operations Demo93# ============================================94echo "Step 5: Running type operations template..."95swift-mtl generate \96 --template aql-04-step-11-type-operations.mtl \97 --model "$MODEL_FILE" \98 --metamodel "$METAMODEL_FILE" \99 --output "$OUTPUT_DIR/docs"100101echo " Generated: type-ops.txt"102echo ""103104# ============================================105# Step 6: File Generation Demo106# ============================================107echo "Step 6: Running file generation template..."108swift-mtl generate \109 --template aql-04-step-18-file-generation.mtl \110 --model "$MODEL_FILE" \111 --metamodel "$METAMODEL_FILE" \112 --output "$OUTPUT_DIR"113114echo " Generated: README.md, *.model.swift, *ViewModel.swift"115echo " Generated: Routes.swift, styles/app.css"116echo ""117118# ============================================119# Step 7: Advanced Patterns (Full Application)120# ============================================121echo "Step 7: Running advanced patterns template..."122swift-mtl generate \123 --template aql-04-step-19-advanced-patterns.mtl \124 --model "$MODEL_FILE" \125 --metamodel "$METAMODEL_FILE" \126 --output "$OUTPUT_DIR"127128echo " Generated: AppConfiguration.swift"129echo " Generated: schema.sql"130echo " Generated: APIRoutes.swift"131echo " Generated: ViewModels/*.swift"132echo " Generated: Validation.swift"133echo ""134135# ============================================136# Summary of Generated Files137# ============================================138echo "=========================================="139echo "Generation Complete!"140echo "=========================================="141echo ""142echo "Generated file structure:"143echo ""144145# Display generated structure (if tree is available)146if command -v tree &> /dev/null; then147 tree "$OUTPUT_DIR"148else149 find "$OUTPUT_DIR" -type f | sort | while read -r file; do150 echo " $file"151 done152fi153154echo ""155echo "Key AQL features demonstrated:"156echo " - Navigation: app.pages, entity.attributes"157echo " - Collection ops: ->size(), ->select(), ->reject()"158echo " - Quantifiers: ->exists(), ->forAll()"159echo " - String ops: .toUpperCase(), .substituteAll()"160echo " - Type ops: oclIsTypeOf(), oclAsType()"161echo " - Conditionals: if-then-else expressions"162echo " - Let bindings: [let x = expression]"163echo " - Sorting: ->sortedBy()"164echo " - Arithmetic: +, -, *, /, ->sum()"165echo ""166167# ============================================168# AQL Expression Examples Summary169# ============================================170echo "=========================================="171echo "AQL Expression Quick Reference"172echo "=========================================="173echo ""174echo "Navigation:"175echo " app.pages - Access collection"176echo " page.components - Chained navigation"177echo " comp.oclAsType(Form).fields - Type cast navigation"178echo ""179echo "Filtering:"180echo " ->select(p | p.requiresAuth) - Keep matching"181echo " ->reject(a | a.isPrimaryKey) - Exclude matching"182echo " ->exists(a | a.isPrimaryKey) - Any match?"183echo " ->forAll(a | a.name <> null) - All match?"184echo ""185echo "Transformation:"186echo " ->collect(e | e.name) - Map to values"187echo " ->sortedBy(e | e.name) - Order by key"188echo " ->flatten() - Flatten nested"189echo ""190echo "Aggregation:"191echo " ->size() - Count elements"192echo " ->sum() - Sum numbers"193echo " ->first(), ->last() - Get endpoints"194echo ""195echo "String Operations:"196echo " .toUpperCase(), .toLowerCase() - Case conversion"197echo " .substituteAll('a', 'b') - Replace all"198echo " .startsWith(), .endsWith() - Prefix/suffix test"199echo ""200echo "Type Operations:"201echo " .oclIsTypeOf(Form) - Exact type check"202echo " .oclIsKindOf(Component) - Inheritance check"203echo " .oclAsType(Form) - Cast to type"204echo ""205echo "Conditional Expressions:"206echo " if cond then val1 else val2 endif - Inline conditional"207echo ""Question 1 of 4
How are AQL expressions used within MTL templates?
Question 2 of 4
What happens when you use [for (item : Type | collection.select(x | x.property > 5))] in an MTL template?
Question 3 of 4
When should you use [let variable = aqlExpression] in templates?
Question 4 of 4
How do you safely handle optional references in MTL templates?
Master advanced AQL query patterns for sophisticated model analysis and cross-model operations.