Laravel多對多關係

Question

我開始使用Eloquent，並且遇到了問題。我試圖建立一個多對多的關係模式+模型。

下面是代碼：

routes.php snippet: 
$user1 = User::findOrFail(1); 
$user2 = User::where('username', '=', 'TestUser')->get(); 
// we make $user1 to follow $user2 
$user1->followedBy()->save($user2); 

用戶模型片段：

public function followedBy() { 
    return $this->belongsToMany('User', 'user_follows', 'user_id', 'follow_id'); 
} 

public function following() { 
    return $this->belongsToMany('User', 'user_follows', 'follow_id', 'user_id'); 
} 

DB模式片段：

Schema::create('user_follows', function(Blueprint $table) 
     { 
      $table->increments('id'); 
      $table->integer('user_id'); 
      $table->integer('follow_id'); 
      $table->timestamps(); 
     }); 

我得到的錯誤，當我參觀路線：

Argument 1 passed to Illuminate\Database\Eloquent\Relations\BelongsToMany::save() must be an instance of Illuminate\Database\Eloquent\Model, instance of Illuminate\Database\Eloquent\Collection given, called in /Applications/MAMP/htdocs/Laravel/proj2/app/routes.php on line 84 and defined 

Answer 1

錯誤說明了一切：

$user2 = User::where('username', '=', 'TestUser')->get(); 
// returns Collection 

你需要這個來代替：

$user2 = User::where('username', '=', 'TestUser')->first(); 
// returns single Model 

---

順便說一句：

// we make $user1 to follow $user2 
$user1->followedBy()->save($user2); 

它$user2遵循$user1和使用這個：

$user1->followedBy()->attach($user2); 

對於save先保存$user2型號，這裏是多餘的。它是在這種情況下使用：

$user2 = new User; 
// assign some properties 
... 
$user1->followedBy()->save($user2);