Laravel 如何创建数据透视表

发布于04月05日

在Laravel 4中，当处理the 4.2 docs中描述的多对多关系时，我如何让Laravel为我创建数据透视表？

对于涉及的两个型号，我是否需要在迁移中添加某些内容？是否需要手动创建数据透视表的迁移？或者，Laravel是如何知道创建数据透视表的？

All I've done so far is add the belongsToMany information to the two respective models, i.e.

class User extends Eloquent 
{
    public function roles()
    {
         return $this->belongsToMany('Role');
     }
 }

但是，这不会触发数据透视表的创建.我错过了哪一步？

推荐答案

It appears as though the pivot table does need to be created manually (i.e. Laravel does not do this automatically). Here's how to do it:

1.) Create a new migration, using singular table names in alphabetical order (default):

php artisan make:migration create_alpha_beta_table --create --table=alpha_beta

2.)在新创建的迁移中，将up函数更改为:

public function up()
{
    Schema::create('alpha_beta', function(Blueprint $table)
    {
        $table->increments('id');
        $table->integer('alpha_id');
        $table->integer('beta_id');
    });
}

3.) Add the foreign key constraints, if desired. (I haven't gotten to that bit, yet).

Now to seed, say, the alpha table, using keys from beta, you can do the following in your AlphaTableSeeder:

public function run()
{
    DB::table('alpha')->delete();

    Alpha::create( array( 
        'all'           =>  'all',
        'your'          =>  'your',
        'stuff'         =>  'stuff',
    ) )->beta()->attach( $idOfYourBeta );
}