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Step 4: Write the templates

Introduction

This section presents typical use cases for templates. Each code example is provided with the following template engines:

  • Hapify (long and short syntaxes)
  • EJS
  • JavaScript

For full details of the Hapify syntax, please refer to this article.

To learn about the EJS syntax, please refer to the official documentation.

Warning

All EJS features are available, except the include feature. This feature is intentionally disabled so that templates do not have access to your file system.

Data model manipulation

Templates receive as input the model object. This object, injected in the templates, describes the data model and all its properties and relations, so that they are easily accessible from the template.

We recommend that you understand its structure before you start writing templates.

Code examples

Names

Create a class for the current data model

This block creates a class for the data model (in pascal case) and defines the primary key name, in snake case.

class <<Model pascal>> {
    private primaryKey = '<<PrimaryField snake>>';
}

class <<M AA>> {
    private primaryKey = '<<P a_a>>';
}

class <%= model.names.pascal %> {
    private primaryKey = '<%= model.fields.primary.names.snake %>';
}

return `class ${model.names.pascal} {
    private primaryKey = '${model.fields.primary.names.snake}';
}`;

class Place {
    private primaryKey = '_id';
}

Conditions

Include dependencies based on field attributes

In a template of type one model, this block imports the MongoDB driver if the data model has a relationship with another.

<<if Fields entity>>
const mongoDb = require('mongodb');
<<endif>>

<<? F tE>>
const mongoDb = require('mongodb');
<<?>>

<% if (model.fields.filter(f => f.type === 'entity').length > 0) { -%>
const mongoDb = require('mongodb');
<% } -%>

let output = '';
if (model.fields.filter(f => f.type === 'entity').length > 0) {
    output += `const mongoDb = require('mongodb');`
}
return output;

const mongoDb = require('mongodb');

Validate the session if the operation requires authentication

In a template of type one model, if the create action requires at most one authenticated user, this block retrieves the logged in user.

Reminder

guest is the most permissive access and admin the least permissive. Therefore admin < owner < authenticated < guest.

<<if CreateAccess lteAuth>>
const user = Session.getCurrent();
<<endif>>

<<? Ac au]>>
const user = Session.getCurrent();
<<?>>

<% if (model.accesses.create.lteAuth) { -%>
const user = Session.getCurrent();
<% } -%>

let output = '';
if (model.accesses.create.lteAuth) {
    output += `const user = Session.getCurrent();`
}
return output;

const user = Session.getCurrent();

Test if the data model is geolocated

In a template of type one model, if the data model has the property isGeolocated (i.e. if the data model contains at least one latitude field and one longitude field) this block imports the map position selection component.

<<if Model isGeolocated>>
<app-map-position-picker [model]="<<Model camel>>"></app-map-position-picker>
<<endif>>

<<? M pGeo>>
<app-map-position-picker [model]="<<M aA>>"></app-map-position-picker>
<<?>>

<% if (model.properties.isGeolocated) { -%>
<app-map-position-picker [model]="<%= model.names.camel %>"></app-map-position-picker>
<% } -%>

let output = '';
if (model.properties.isGeolocated) {
    output += `<app-map-position-picker [model]="${model.names.camel}"></app-map-position-picker>`
}
return output;

<app-map-position-picker [model]="place"></app-map-position-picker>

Getting relationships based on cardinality

This example creates a method that retrieves entities from a store, depending on the type of relationship: one-to-one, one-to-many or many-to-many.

class <<Model pascal>> extends BaseModel {
<<for Fields entity field>>
    get<<field pascal>>() {
    <<if field oneOne or oneMany>>
        return this.<<field.model camel>>Store.findOne(this.properties.<<field camel>>);
    <<elseif field manyMany>>
        return this.<<field.model camel>>Store.findMany(this.properties.<<field camel>>);
    <<endif>>
    }
<<endfor>>
}

class <<M AA>> extends BaseModel {
<<@ F tE f>>
    get<<f AA>>() {
    <<? f tEoo + tEom>>
        return this.<<f.m aA>>Store.findOne(this.properties.<<f aA>>);
    <<?? f tEmm>>
        return this.<<f.m aA>>Store.findMany(this.properties.<<f aA>>);
    <<?>>
    }
<<@>>
}

class <%= model.names.pascal %> extends BaseModel {
<% for (let field of model.fields.filter(f => f.type === 'entity')) { -%>
    get<%= field.names.pascal %>() {
    <% if (field.subtype === 'oneOne' || field.subtype === 'oneMany') { -%>
        return this.<%= field.model.names.camel %>Store.findOne(this.properties.<%= field.names.camel %>);
    <% } else if (field.subtype === 'manyMany') { -%>
        return this.<%= field.model.names.camel %>Store.findMany(this.properties.<%= field.names.camel %>);
    <% } -%>
    }
<% } -%>
}

let output = '';
output += `class ${model.names.pascal} extends BaseModel {
    ${getRelations()}
}`;

function getRelations() {
    return model.fields.filter(f => f.type === 'entity').reduce((acc, field) => {
        return acc + getRelation(field) + '\n\t';
    }, '');
}

function getRelation(field) {
    let method = '';
    if (field.subtype === 'oneOne' || field.subtype === 'oneMany') {
        method = 'findOne';
    } else if (field.subtype === 'manyMany') {
        method = 'findMany';
    } else {
        return '';
    }
    return `get${field.names.pascal}() {
        return this.${field.model.names.camel}Store.${method}(this.properties.${field.names.camel});
    }`;
}

return output;

class User extends BaseModel {
    getAvatar() {
        return this.avatarStore.findOne(this.properties.avatar);
    }
    getBookmarks() {
        return this.placeStore.findMany(this.properties.bookmarks);
    }
}

Iterations

Fill an array with all hidden field names

In a template of type one model, this block creates an array (in JavaScript) that contains the names of hidden fields (in camel case).

const hiddenFields = [
<<for Fields hidden field>>
    '<<field camel>>',
<<endfor>>
];

const hiddenFields = [
<<@ F hd f>>
    '<<f aA>>',
<<@>>
];

const hiddenFields = [
<% for (let field of model.fields.filter(f => f.hidden)) { -%>
    '<%= field.names.camel %>',
<% } -%>
];

let output = '';
const hiddenFieldsNames = model.fields
    .filter(f => f.hidden)
    .map(f => `'${f.names.camel}'`);
output += `const hiddenFields = [
    ${hiddenFieldsNames.join(",\n\t")}
];`;
return output;

const hiddenFields = [
    'password',
    'token',
];

Create an array containing all possible values of an enumeration

In a template of type one model, this block defines enumeration values as arrays (in constant case).

<<for Fields enum field>>
const <<field camel>>Values = [
    <<for field.enum e>>
    '<<e constant>>',
    <<endfor>>
];
<<endfor>>

<<@ F tU f>>
const <<f aA>>Values = [
    <<@ f.e e>>
    '<<e A_A>>',
    <<@>>
];
<<@>>

<% for (let field of model.fields.filter(f => f.type === 'enum')) { -%>
const <%= field.names.camel %>Values = [
    <% for (let e of field.enum) { -%>
    '<%= e.names.constant %>',
    <% } -%>
];
<% } -%>

let output = '';
for (let field of model.fields.filter(f => f.type === 'enum')) {
    const enums = field.enum.map(e => `'${e.names.constant}'`);
    output += `const ${field.names.camel}Values = [
    ${enums.join(',\n\t')}
];`;
}
return output;

const roleValues = [
    'ADMIN',
    'USER',
    'CUSTOMER',
];
const statusValues = [
    'BUSY',
    'AVAILABLE',
    'OUT_OF_OFFICE',
];

Create an index file of all models

In a template of type all models, this will call the files of all models.

<<for Models model>>
require_once('./<<model kebab>>.php');
<<endfor>>

<<@ M m>>
require_once('./<<m a-a>>.php');
<<@>>

<% for (let model of models) { -%>
require_once('./<%= model.names.kebab %>.php');
<% } -%>

let output = '';
for (let model of models) {
    output += `require_once('./${model.names.kebab}.php');\n`;
}
return output;

require_once('./user.php');
require_once('./place.php');
require_once('./service.php');
require_once('./place-category.php');

Create an index file with models accessible only by administrators

If you want to limit the previous loop for models that contain only admin operations :

<<for Models onlyAdmin model>>
require_once('./<<model kebab>>.php');
<<endfor>>

<<@ M pOAd m>>
require_once('./<<m a-a>>.php');
<<@>>

<% for (let model of models.filter(m => m.accesses.properties.onlyAdmin)) { -%>
require_once('./<%= model.names.kebab %>.php');
<% } -%>

let output = '';
for (let model of models.filter(m => m.accesses.properties.onlyAdmin)) {
    output += `require_once('./${model.names.kebab}.php');\n`;
}
return output;

require_once('./menu.php');
require_once('./menu-part.php');
require_once('./menu-item.php');
require_once('./order.php');

Set default value based on data type

In a template of type one model, this block assigns a value to the field based on its type for all internal fields. If the type of the field is boolean, it assigns the value false, if the type is string, it assigns the value '', if the type is number, it assigns the value 0, otherwise it assigns the value NULL. This template generates PHP.

<<for Fields internal field>>
    <<if field boolean>>
$default<<field pascal>> = false;
    <<elseif field string>>
$default<<field pascal>> = '';
    <<elseif field number>>
$default<<field pascal>> = 0;
    <<else>>
$default<<field pascal>> = NULL;
    <<endif>>
<<endfor>>

<<@ F in f>>
    <<? f tB>>
$default<<f AA>> = false;
    <<?? f tS>>
$default<<f AA>> = '';
    <<?? f tN>>
$default<<f AA>> = 0;
    <<??>>
$default<<f AA>> = NULL;
    <<?>>
<<@>>

<% for (let field of model.fields.filter(f => f.internal)) { -%>
    <% if (field.type === 'boolean') { -%>
$default<%= field.names.pascal %> = false;
    <% } else if (field.type === 'string') { -%>
$default<%= field.names.pascal %> = '';
    <% } else if (field.type === 'number') { -%>
$default<%= field.names.pascal %> = 0;
    <% } else { -%>
$default<%= field.names.pascal %> = NULL;
    <% } -%>
<% } -%>

let output = '';
for (let field of model.fields.filter(f => f.internal)) {
    output += `$default${field.names.pascal} = ${getDefaultValue(field)};\n`
}
return output;

function getDefaultValue(field) {
    switch (field.type) {
        case 'boolean':
            return 'false';
        case 'string':
            return "''";
        case 'number':
            return '0';
        default:
            return 'NULL';
    }
}

$defaultId = '';
$defaultCreatedAt = NULL;
$defaultStock = 0;

Import all dependencies

In a template of type one model, this block imports other data models linked by fields of type entity. If the data model has a self-dependency, it will not be included in the loop.

<<for Dependencies dep>>
import {<<dep pascal>>} from '../<<dep kebab>>';
<<endfor>>

<<@ D d>>
import {<<d AA>>} from '../<<d a-a>>';
<<@>>

<% for (let dep of model.dependencies.list) { -%>
import {<%= dep.names.pascal %>} from '../<%= dep.names.kebab %>';
<% } -%>

let output = '';
for (let dep of model.dependencies.list) {
    output += `import {${dep.names.pascal}} from '../${dep.names.kebab}';\n`;
}
return output;

import {Restaurant} from '../restaurant';
import {User} from '../user';
import {MenuPart} from '../menu-part';
import {MenuItem} from '../menu-item';

You can also filter by referent field attributes. This block excludes data models with hidden referent fields:

<<for Dependencies not hidden dep>>
import {<<dep pascal>>} from '../<<dep kebab>>';
<<endfor>>

<<@ D !hd d>>
import {<<d AA>>} from '../<<d a-a>>';
<<@>>

<% for (let dep of model.dependencies.filter(f => !f.hidden)) { -%>
import {<%= dep.names.pascal %>} from '../<%= dep.names.kebab %>';
<% } -%>

let output = '';
for (let dep of model.dependencies.filter(f => !f.hidden)) {
    output += `import {${dep.names.pascal}} from '../${dep.names.kebab}';\n`;
}
return output;

import {PlaceCategory} from '../place-category';
import {Service} from '../service';
import {User} from '../user';

Cascading deletion

In a template of type one model, this block enumerates all data models that refer to the current data model and deletes them. The first iteration loops over all the data models that have a dependency on it. The second iteration loops over all the entity relations contained in these dependent data models.

Note

The ReferencedIn array contains all data models that refer to the current data model through entity type fields. Only entity fields that are referencing are defined in these referencing data models. Therefore, if you loop over the fields in the referring data models, you will not be confused by other fields.

<<for ReferencedIn referrer>>
    <<for referrer.fields field>>
await db.collection('<<referrer pascal>>').deleteMany({ <<field snake>>: id });
    <<endfor>>
<<endfor>>

<<@ R m>>
    <<@ m.f f>>
await db.collection('<<m AA>>').deleteMany({ <<f a_a>>: id });
    <<@>>
<<@>>

<% for (let referrer of model.referencedIn) { -%>
    <% for (let field of referrer.fields) { -%>
await db.collection('<%= referrer.names.pascal %>').deleteMany({ <%= field.names.snake %>: id });
   <% } -%>
<% } -%>

let output = '';
for (let referrer of model.referencedIn) {
    for (let field of referrer.fields) {
        output += `await db.collection('${referrer.names.pascal}').deleteMany({ ${field.names.snake}: id });\n`;
    }
}
return output;

await db.collection('Place').deleteMany({ owner: id });
await db.collection('Bookmark').deleteMany({ owner: id });
await db.collection('Message').deleteMany({ sender: id });
await db.collection('Message').deleteMany({ recipient: id });
await db.collection('Conversation').deleteMany({ participants: id });
await db.collection('Conversation').deleteMany({ closed_by: id });
await db.collection('ConversationReport').deleteMany({ complainant: id });
await db.collection('ConversationReport').deleteMany({ defendant: id });

Notes

It is possible to add notes to a field or a model. Here is how to find them in the templates:

<<if Model hasNotes>>// <<! Model>><<endif>>
export class <<Model pascal>> {
    <<for Fields field>>
    public <<field camel>>; <<if field hasNotes>>// <<! field>><<endif>>
    <<endfor>>
}

<<? M hN>>// <<! M>><<?>>
export class <<M AA>> {
    <<@ F f>>
    public <<f aA>>; <<? f hN>>// <<! f>><<?>>
    <<@>>
}

<% if (model.hasNotes) { %>// <%= model.notes %><% } %>
export class <%= model.names.pascal %> {
<% for (const field of model.fields.list) { -%>
    public <%= field.names.camel %>; <% if (field.hasNotes) { %>// <%= field.notes %><% } %>
<% } %>
}

let output = '';
if (model.hasNotes) { output += `// ${model.notes}\n`; }
output += `export class ${model.names.pascal} {
${getFields()}}`;

function getFields() {
    let fields = '';
    for (const field of model.fields.list) {
        fields += `    public ${field.names.camel};`;
        if (field.hasNotes) { fields += ` // ${field.notes}`; }
        fields += `\n`;
    }
    return fields;
}
return output;

// A user can only list its own bookmarks
export class Bookmark {
    public id;
    public owner; // Current user when creating the bookmark
    public place;
}

Tip

With the Hapify syntax it is also possible to display notes using interpolation: <<= root.notes >> or <<= model.notes >> for a model or <<= field.notes >> for a field.

Meta-data

It is possible to add meta-data to a field or a model. Here is how to find them in the templates:

// The model's plural name is <<-Model plural camel>>

// The model's plural name is <<-M plural aA>>

// The model's plural name is <%=model.meta.plural.camel%>

output = `// The model's plural name is ${model.meta.plural.camel}`;
return output;

// The model's plural name is bookmarks

Test if a meta-data is defined

It is also possible to test if a metadata exists before using it:

<<for Fields field>>
    <<< if (field.meta.plural) { >>>
// Plural of <<field camel>> is <<-field plural camel>>
    <<< } >>>
<<endfor>>

<<@ F f>>
    <<< if (f.meta.plural) { >>>
// Plural of <<f aA>> is <<-f plural aA>>
    <<< } >>>
<<@>>

<% for(const field of model.fields.list) { -%>
    <% if (field.meta.plural) { -%>
// Plural of <%=field.names.camel%> is <%=field.meta.plural.camel%>
    <% } -%>
<% } -%>

output = '';
    for (const field of model.fields.list) {
        if (field.meta.plural) {
            output += `// Plural of ${field.names.camel} is ${field.meta.plural.camel}\n`;
        }
    }
return output;

// Plural of owner is owners
// Plural of place is places

Tip

You can force the insertion of meta for fields or models by setting a model validator.

Exclusion of generated files

It is possible to exclude some files from the generation. If the template returns an empty string or a string containing only spaces, then no file will be generated for this template/data model pair.