laravel 保存多对多关系，同步/附加不存在？
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Saving many-to-many relationship, sync/attach doesn't exist?
提问by Zed
I have two following 2 models in many-to-many relationship :
我有以下两个多对多关系的模型：
use Illuminate\Database\Eloquent\Model;
class Permission extends Model
{
/**
* The database table used by the model.
*
* @var string
*/
protected $table = 'permissions';
/*
|--------------------------------------------------------------------------
| Relationship Methods
|--------------------------------------------------------------------------
*/
/**
* many-to-many relationship method
*
* @return QueryBuilder
*/
public function roles()
{
return $this->belongsToMany('App\Admin\Role');
}
}
and
和
class Role extends Model
{
/**
* The database table used by the model.
*
* @var string
*/
protected $table = 'roles';
/*
|--------------------------------------------------------------------------
| Relationship Methods
|--------------------------------------------------------------------------
*/
/**
* many-to-many relationship method.
*
* @return QueryBuilder
*/
public function users()
{
return $this->belongsToMany('App\Admin\User');
}
/**
* many-to-many relationship method.
*
* @return QueryBuilder
*/
public function permissions()
{
return $this->belongsToMany('App\Admin\Permission');
}
}
What I'm trying to do here, is to create a page where new Role can be created, and associate that role with already created Permissions:
我在这里尝试做的是创建一个可以创建新角色的页面，并将该角色与已创建的权限相关联：
@foreach ($permissions as $permission)
<label class="checkbox">
<input type="checkbox" value="{{ $permission->id }}" name="permissions[]" id="permission_{{ $permission }} }}">
{{ $permission->permission_title }}
</label>
@endforeach
and in the controller I tried this to extract selected permissions from the page and save everything:
在控制器中，我尝试从页面中提取选定的权限并保存所有内容：
// logic to save role
$role->save();
$permissions = Input::get('permissions');
$role->permissions->sync($permissions);
However after the last statement is executed I get the following error:
exception 'BadMethodCallException' with message 'Method sync does not exist.'
The same error I get for attachas well. Also, I'm not sure if I'm supposed to provide somewhere the name of the intermediate table permission_role? Thanks.
但是，在执行最后一条语句后，我收到以下错误：
exception 'BadMethodCallException' with message 'Method sync does not exist.' 我也遇到了同样的错误attach。另外，我不确定是否应该在某处提供中间表的名称permission_role？谢谢。
回答by Hammerbot
You need to use the following:
您需要使用以下内容：
$role->permissions()->sync($permissions);
Don't forget the ()
不要忘记 ()
EDIT: Some more explanations:
编辑：更多解释：
$role->permissionsis a Collection instance.
$role->permissions是一个集合实例。
$role->permissions()is a belongsToManyinstance which contains the sync()method
$role->permissions()是一个belongsToMany包含sync()方法的实例
