Cannot access model from many to many relation

Question

I am using Laravel. I am trying to relate user model and message model to many-many relation. When I access a users message it is saying function not defined. But the that function is defined. This is the error I am getting

 Call to undefined method Illuminate\Database\Eloquent\Collection::messages()

User Model.

  public function docs(){
    return $this->belongsToMany('Doc');
  } 

  public function messages(){
    return $this->belongsToMany('Message');
  } 

Message Model.

public function users(){
    return $this->belongsToMany('User');
} 

I am trying to store message for selected users. This is where the error rises. I have also set the pivot table.

Messages Controller.

public function store()
{
    //
    $input = Input::only('title', 'body', 'sel_users');
    $msg = Input::only('title', 'body');
    $sel_users = Input::only('sel_users');
    $this->messageForm->validate($input);
    $insert = Message::create($msg);
    $id = $insert['id'];
    foreach ($sel_users as $userid) {
        $user = User::find($userid);
        $user->messages()->attach($id);
    }
    return Redirect::route('messages.index');

}

Answer 1

Your problem is that userid in the loop is an array not single id:

foreach ($sel_users as $userid) {
    $user = User::find($userid);  // find() provided with array returns collection...
    $user->messages()->attach($id);  // .. so here you can't call messages() on that collection
}

// it works the same as:
// User::whereIn('id', $userid)->get();

This is because Input::only(...) returns array, and you must have had an array of ids in sel_users too, so:

$sel_users = Input::only('sel_users');
// $sel_users = array('sel_users' => array( id1, id2 ...) )

What you wanted here is this:

$sel_users = Input::get('sel_users');
// $sel_users = array( id1, id2 ...)

Then the rest of your code will work as expected.