Yii 2 Many-to-many

Implementation of Many-to-many relationship
for Yii 2 framework.

• Installation
• Features
• Creating editable attribute
• Attaching and configuring behavior
• Filling relations
• Saving relations without massive assignment
• Adding attribute as safe
• Adding control to view
• Relation features
• Running tests

Installation

The preferred way to install this extension is through composer.

Either run

php composer.phar require --prefer-dist arogachev/yii2-many-to-many

or add

"arogachev/yii2-many-to-many": "0.2.*"

to the require section of your composer.json file.

Features

• Configuring using existing hasMany relations
• Multiple relations
• No extra queries. For example, if initially model has 100 related records,
  after adding just one, exactly one row will be inserted. If nothing was changed, no queries will be executed.
• Auto filling of editable attribute
• Validator for checking if the received list is valid

Creating editable attribute

Simply add public property to your ActiveRecord model like this:

/**
 * @var array
 */
public $editableUsers = [];

It will store primary keys of related records during update.

Attaching and configuring behavior

First way is to explicitly specify all parameters:

use arogachev\ManyToMany\behaviors\ManyToManyBehavior;

/**
 * @inheritdoc
 */
public function behaviors()
{
    return [
        [
            'class' => ManyToManyBehavior::className(),
            'relations' => [
                [
                    'editableAttribute' => 'editableUsers', // Editable attribute name
                    'table' => 'tests_to_users', // Name of the junction table
                    'ownAttribute' => 'test_id', // Name of the column in junction table that represents current model
                    'relatedModel' => User::className(), // Related model class
                    'relatedAttribute' => 'user_id', // Name of the column in junction table that represents related model
                ],
            ],
        ],
    ];
}

But more often we also need to display related models,
so it's better to define relation for that and use it for both display and behavior configuration.
Both ways (via and viaTable) are considered valid:

Using viaTable:

/**
 * @return \yii\db\ActiveQuery
 */
public function getUsers()
{
    return $this->hasMany(User::className(), ['id' => 'user_id'])
        ->viaTable('tests_to_users', ['test_id' => 'id'])
        ->orderBy('name');
}

Using via (requires additional model for junction table):

/**
 * @return \yii\db\ActiveQuery
 */
public function getTestUsers()
{
    return $this->hasMany(TestUser::className(), ['test_id' => 'id']);
}

/**
 * @return \yii\db\ActiveQuery
 */
public function getUsers()
{
    return $this->hasMany(User::className(), ['id' => 'user_id'])
        ->via('testUsers')
        ->orderBy('name');
}

Order is not required.

Then just pass the name of this relation and all other parameters will be fetched automatically.

/**
 * @inheritdoc
 */
public function behaviors()
{
    return [
        [
            'class' => ManyToManyBehavior::className(),
            'relations' => [
                [
                    'name' => 'users',
                    // This is the same as in previous example
                    'editableAttribute' => 'editableUsers',
                ],
            ],
        ],
    ];
}

Additional many-to-many relations can be added exactly the same.
Note that even for one relation you should declare it as a part of relations section.

Filling relations

By default, editableAttribute of each found model will be populated with ids of related models (eager loading is
used). If you want more manual control, prevent extra queries, disable autoFill option:

'autoFill' => false,

and fill it only when it's needed, for example in update action of controller. This is recommended way of using.

public function actionUpdate($id)
{
    $model = $this->findModel($id);
    $model->getManyToManyRelation('users')->fill();
    // ...
}

Alternatively you can specify conditions of filling in closure:

'autoFill' => function ($model) {
    return $model->scenario == Test::SCENARIO_UPDATE; // boolean value
}

Even it's possible to do something like this:

'autoFill' => function ($model) {
    return Yii::$app->controller->route == 'tests/default/update';
}

but it's not recommended for usage because model is not appropriate place for handling routes.

Saving relations without massive assignment

When creating model:

$model = new Test;
$model->editableUsers = [1, 2];
$model->save();

When updating model ('autoFill' => true):

$model = new Test;
$model->editableUsers = [1, 2];
$model->save();

When updating model ('autoFill' => false, manual filling):

$model = new Test;
$model->getManyToManyRelation('users')->fill();
var_dump($model->editableUsers) // [1, 2]
$model->editableUsers = [1, 2, 3];
$model->save();

When updating model ('autoFill' => false, without manual filling):

$model = new Test;
var_dump($model->editableUsers) // empty array
$model->save();

In this case many-to-many relations will stay untouched.

Adding attribute as safe

Add editable attribute to model rules for massive assignment.

Either mark it as safe at least:

public function rules()
{
    ['editableUsers', 'safe'],
}

Or use custom validator:

use arogachev\ManyToMany\validators\ManyToManyValidator;

public function rules()
{
    ['editableUsers', ManyToManyValidator::className()],
}

Validator checks list for being array and containing only primary keys presented in related model.
It can not be used without attaching ManyToManyBehavior.

Adding control to view

Add control to view for managing related list. Without extensions it can be done with multiple select:

<?= $form->field($model, 'editableUsers')->dropDownList(User::getList(), ['multiple' => true]) ?>

Example of getList() method contents (it needs to be placed in User model):

use yii\helpers\ArrayHelper;

/**
 * @return array
 */
public static function getList()
{
    $models = static::find()->orderBy('name')->all();

    return ArrayHelper::map($models, 'id', 'name');
}

Relation features

You can access many-to-many relation like so:

$relation = $model->getManyToManyRelation('users');

users can be value of either name or table relation property specified in config.

You can fill editableAttribute with ids of related records like so:

$model->getManyToManyRelation('users')->fill();

You can get added and deleted primary keys of related models for specific relation like so:

$addedPrimaryKeys = $model->getManyToManyRelation('users')->getAddedPrimaryKeys();
$deletedPrimaryKeys = $model->getManyToManyRelation('users')->getDeletedPrimaryKeys();

Note that they are only available after the model was saved so you can access it after $model->save() call
or in afterSave() event handler.

Running tests

Install dependencies:

composer install

Add database config (tests/config/db-local.php file) with following contents:

<?php

return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=localhost;dbname=yii2_many_to_many',
    'username' => 'root',
    'password' => '',
];

You can change dbname, username and password how you want. Make sure create database and user before running
tests.

Run tests:

vendor/bin/phpunit