無法刪除一對多關系中的記錄

Question

我在laravel中遇到以下錯誤：有2個表的用戶和具有多對多關系的軌道，中間表的名稱為track_user我正在嘗試刪除記錄，但無法執行

Unhandled Exception

Message:

Call to a member function track() on a non-object
Location:

C:\wamp\www\integron\application\controllers\track.php on line 50

MySQL錯誤：

SQL query:
DELETE FROM  `integron`.`tracks` WHERE  `tracks`.`id` =2

MySQL said: 

#1451 - Cannot delete or update a parent row: a foreign key constraint fails (`integron`.`track_user`, CONSTRAINT `track_user_project_id_foreign` FOREIGN KEY (`track_id`) REFERENCES `tracks` (`id`)) 

用戶模型：

<?php 
class User extends Eloquent{
public static $table = 'users';
public function tracks()
    {
        return $this->has_many_and_belongs_to('Track');
    }

軌道型號：

<?php 
class Track extends Eloquent{
public static $table = 'tracks';
public function users()
    {
        return $this->has_many_and_belongs_to('User');
    }

控制者

//this funciton is working properly

public function post_trackUpdate($id){
    $track = Track::find($id);
    $track->name = Input::get('name');
    $track->description = Input::get('desc');
    $track->save();
}
//this funciton is not working properly
public function get_trackDelete($id){
    $track = Track::find($id);
    $track->delete();
}

..

//an alternate which i tried but didnt work either
public function get_trackDelete($id){
    $user=User::find($id);
    $user->tracks()->delete();
    Session::flash('result','track Details deleted');
    return Redirect::to('track');
}

Answer 1

從laravel文檔中，“連接的相反是分離：”

在http://four.laravel.com/docs/eloquent中查找

離開的例子：

$circle->users()->detach($user_id);
$circle->save();

Answer 2

您必須首先從復合user_track表中刪除記錄。 只有這樣，您才能刪除跟蹤表中的父記錄。