Laravel口才ORM中的多租户关系

Question

Once again this is a follow up question to :

Multi tenancy in Laravel Eloquent ORM

This time around I have questions for using relationships in a multi-tenancy environment for eloquent models.

Given a Product model :

class Product extends Eloquent {

public function accessories()
{
    return $this->belongsToMany('Accessory', 'product_accessory', 'product_id', 'accessory_id')
                ->withPivot('id')
                ->withTimestamps();
}

Is that any easy way to make sure that the relationship method accessories() uses the correct database connection? Right now when I do a attach method like this :

$product->accessories()->attach($accessory->id, $attributes);

the accessories method seem to be pointing to another database different from the $product entity. I believe this is because the Accessory model connection does not get changed when the relationship is instantiated.

Answer 1

If you see my answer to your original question regarding Model Events & Observers, this should inherently solve this problem too: Multi tenancy in Laravel Eloquent ORM

All the Eloquent relational methods: attach, associate etc... all trigger the respective Model Events as detailed here: http://laravel.com/docs/5.0/eloquent#model-events

If you setup a Model Observer to manipulate the connection in use pre & post saving of specific models, all your relational calls will have the database connection set appropriately automatically.

Hope this helps

-- Edit in response to comment

Hi yulun,

Sorry I mistook your accessories call for associate. (Saving relations)

However you should be able to achieve a similar result where your relationship is defined. See below example:

class ProductModel extends Eloquent {

    protected $table = 'products';

    protected $connection;

    protected $databases = [
        'default' => 'mysql-key1',
        'products' => 'mysql-key2'
    ];

    public function __construct(Connection $connection)
    {
        $this->connection = $connection;
    }

    public function accessories()
    {
        $this->connection->reconnect($this->databases['products']);
        $accessories = $this->hasMany('AccessoriesModel');
        $this->connection->reconnect($this->databases['default']);

        return $accessories;
    }
}

You could then take it further by creating an abstract class that all affected models can extend, eg:

abstract class DatabaseModel extends Eloquent {

     protected $connection;

     protected $databases = [
         'default' => 'mysql-key1',
         'products' => 'mysql-key2'
     ];

     public function __construct(Connection $connection)
     {
         $this->connection = $connection;
     }

    protected function setProductsDatabase()
    {
        $this->connection->reconnect($this->databases['products']);
    }

    protected function resetDatabaseConnection()
    {
        $this->connection->reconnect($this->databases['default']);
    }
}

class ProductModel extends DatabaseModel {

    protected $table = 'products';

    public function accessories()
    {
        $this->setProductsDatabase();
        $accessories = $this->hasMany('AccessoriesModel');
        $this->resetDatabaseConnection();

        return $accessories;
    }
}

This way, everything will behave "naturally" without the need for any additional code providing your relationships have been configured correctly.

A neater, but more complicated solution would be to instead of manipulating the database in the model you could fire your own "retrieving" event, you could then add an event handler to the Model Observer for your custom "retrieving" event - This would be my preference, and you can find more information on how to do it here: http://laravel.io/forum/05-24-2014-how-could-i-create-custom-model-events?page=1

Hope this helps

Answer 2

Using cues from Beevee's answer, we can also extend the Eloquent class as an base model to use a session based or config based connection such as

class BaseModel extends Eloquent {

public function __construct(array $attributes = array())
{
    parent::__construct($attributes);

    $this->setConnection(\DB::getDefaultConnection());
}

}

This way, all the relation methods will automatically be instantiated to use the connection.

class Product extends BaseModel {

public function accessories()
{
  return $this->belongsToMany('Accessory', 'product_accessory', 'product_id', 'accessory_id')
            ->withPivot('id')
            ->withTimestamps();
}

provided the Accessory class also extends BaseModel. This way, you can change the database connection at runtime at will.