Yii2 Active Record Save Relations Behavior
==========================================
Automatically validate and save related Active Record models.

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Features
--------
- Both `hasMany()` and `hasOne()` relations are supported
- Works with existing as well as new related models
- Composite primary keys are supported
- Only pure Active Record API is used so it should work with any DB driver
- As of 1.5.0 release, related records can now be deleted along with the main model


Installation
------------

The preferred way to install this extension is through [composer](http://getcomposer.org/download/).

Either run

```
php composer.phar require --prefer-dist la-haute-societe/yii2-save-relations-behavior "*"
```

or add

```
"la-haute-societe/yii2-save-relations-behavior": "*"
```

to the require section of your `composer.json` file.


Configuring
-----------

Configure model as follows

```php
use lhs\Yii2SaveRelationsBehavior\SaveRelationsBehavior;

class Project extends \yii\db\ActiveRecord
{
    use SaveRelationsTrait; // Optional

    public function behaviors()
    {
        return [
            'timestamp'     => TimestampBehavior::className(),
            'blameable'     => BlameableBehavior::className(),
            ...
            'saveRelations' => [
                'class'     => SaveRelationsBehavior::className(),
                'relations' => [
                    'company',
                    'users',
                    'projectLinks' => ['cascadeDelete' => true],
                    'tags'  => [
                        'extraColumns' => function ($model) {
                            /** @var $model Tag */
                            return [
                                'order' => $model->order
                            ];
                        }
                    ]
                ],
            ],
        ];
    }

    public function transactions()
    {
        return [
            self::SCENARIO_DEFAULT => self::OP_ALL,
        ];
    }

    ...


    /**
     * @return ActiveQuery
     */
    public function getCompany()
    {
        return $this->hasOne(Company::className(), ['id' => 'company_id']);
    }

    /**
     * @return ActiveQuery
     */
    public function getProjectUsers()
    {
        return $this->hasMany(ProjectUser::className(), ['project_id' => 'id']);
    }

    /**
     * @return ActiveQuery
     */
    public function getUsers()
    {
        return $this->hasMany(User::className(), ['id' => 'user_id'])->via('ProjectUsers');
    }
    
    /**
     * @return ActiveQuery
     */
    public function getProjectLinks()
    {
        return $this->hasMany(ProjectLink::className(), ['project_id' => 'id']);
    }

    /**
     * @return ActiveQuery
     */
    public function getTags()
    {
        return $this->hasMany(Tag::className(), ['id' => 'tag_id'])->viaTable('ProjectTags', ['project_id' => 'id']);
    }
}
```

> Though not mandatory, it is highly recommended to activate the transactions for the owner model.


Usage
-----

Every declared relations in the `relations` behavior parameter can now be set and saved as follow:

```php
$project = new Project();
$project->name = "New project";
$project->company = Company::findOne(2);
$project->users = User::findAll([1,3]);
$project->save();
```

You can set related model by only specifying its primary key:

```php
$project = new Project();
$project->name = "Another project";
$project->company = 2;
$project->users = [1,3];
$project->save();
```

You can even set related models as associative arrays like this:

```php
$project = Project::findOne(1);
$project->company = ['name' => 'GiHub', 'description' => 'Awesome']; // Will create a new company record
// $project->company = ['id' => 3, 'name' => 'GiHub', 'description' => 'Awesome']; // Will update an existing company record
$project->save();
```

Attributes of the related model will be massively assigned using the `load() method. So remember to declare the according attributes as safe in the rules of the related model.

> **Note:**
> Only newly created or changed related models will be saved.

> See the PHPUnit tests for more examples.


Populate additional junction table columns in a many-to-many relation
---------------------------------------------------------------------
In a many-to-many relation involving a junction table additional column values can be saved to the junction table for each model.
See the configuration section for examples.

> **Note:**
> If junction table properties are configured for a relation the rows associated with the related models in the junction table will be deleted and inserted again on each saving
> to ensure that changes to the junction table properties are saved too.


Validation
----------
Every declared related models will be validated prior to be saved. If any validation fails, for each related model attribute in error, an error associated with the named relation will be added to the owner model.

For `hasMany()` relations, the index of the related model will be used to identify the associated error message.

It is possible to specify the validation scenario for each relation by declaring an associative array in which the `scenario` key must contain the needed scenario value.
For instance, in the following configuration, the `links ` related records will be validated using the `Link::SOME_SCENARIO` scenario:

```php
...
    public function behaviors()
    {
        return [
            'saveRelations' => [
                'class'     => SaveRelationsBehavior::className(),
                'relations' => ['company', 'users', 'links' => ['scenario' => Link::SOME_SCENARIO]]
            ],
        ];
    }  
...
```

It is also possible to set a relation scenario at runtime using the `setRelationScenario` as follow:

```php
$model->setRelationScenario('relationName', 'scenarioName');
```

> **Tips:**
> For relations not involving a junction table by using the `via()` or `viaTable()` methods, you should remove the attributes pointing to the owner model from the 'required' validation rules to be able to pass the validations.

> **Note:**
> If an error occurs for any reason during the saving process of related records in the afterSave event, a `yii\db\Exception` will be thrown on the first occurring error.
> An error message will be attached to the relation attribute of the owner model.
> In order to be able to handle these cases in a user-friendly way, one will have to catch `yii\db\Exception` exceptions.


Delete related records when the main model is deleted
-----------------------------------------------------

For DBMs with no built in relational constraints, as of 1.5.0 release, one can now specify a relation to be deleted along with the main model.

To do so, the relation should be declared with a property `cascadeDelete` set to true.
For example, related `projectLinks` records will automaticaly be deleted when the main model will be deleted:

```php
...
'saveRelations' => [
    'class'     => SaveRelationsBehavior::className(),
    'relations' => [
        'projectLinks' => ['cascadeDelete' => true]
    ],
],
...
```

> **Note:**
> Every records related to the main model as they are defined in their `ActiveQuery` statement will be deleted.


Populate the model and its relations with input data
----------------------------------------------------
This behavior adds a convenient method to load relations models attributes in the same way that the load() method does.
Simply call the `loadRelations()` with the according input data.

For instance:

```php
$project = Project::findOne(1);
/**
 * $_POST could be something like:
 * [
 *     'Company'     => [
 *         'name' => 'YiiSoft'
 *     ],
 *     'ProjectLink' => [
 *         [
 *             'language' => 'en',
 *             'name'     => 'yii',
 *             'link'     => 'http://www.yiiframework.com'
 *         ],
 *         [
 *             'language' => 'fr',
 *             'name'     => 'yii',
 *             'link'     => 'http://www.yiiframework.fr'
 *         ]
 *     ]
 * ];
 */
$project->loadRelations(Yii::$app->request->post());
```

You can even further simplify the process by adding the `SaveRelationsTrait` to your model.
In that case, a call to the `load()` method will also automatically trigger a call to the `loadRelations()` method by using the same data, so you basically won't have to change your controllers.

The `relationKeyName` property can be used to decide how the relations data will be retrieved from the data parameter. 

Possible constants values are:
* `SaveRelationsBehavior::RELATION_KEY_FORM_NAME` (default): the key name will be computed using the model [`formName()`](https://www.yiiframework.com/doc/api/2.0/yii-base-model#formName()-detail) method
* `SaveRelationsBehavior::RELATION_KEY_RELATION_NAME`: the relation name as defined in the behavior declarations will be used