laravel Eloquent ORM delete() 方法

问题描述

我正在学习 Laravel.我使用 Eloquent ORM 删除方法，但得到不同的结果.不是真或假而是空.我设置了一个资源路由，在UsersController中有一个destroy方法.

Hi I am studying laravel. I use Eloquent ORM delete method but I get a different result.Not true or false but null. I set an resource route and there is a destroy method in UsersController.

public function destroy($id){

  $res=User::find($id)->delete();
  if ($res){
    $data=[
    'status'=>'1',
    'msg'=>'success'
  ];
  }else{
    $data=[
    'status'=>'0',
    'msg'=>'fail'
  ];
  return response()->json($data);

但是我总是得到响应{"status":"0","msg":"failed"}，数据库中的记录被删除了.

But I always get a response {"status":"0","msg":"failed"},the record in the database is deleted.

然后我使用 dd($res) .它在页面中显示为空.

Then I use dd($res) .It shows null in the page.

但是从我学习的课程中，它返回一个布尔值 true 或 false.

But from the course I learn it returns a boolean value true or false.

我的代码有错误吗?

你能告诉我从数据库中删除数据时可以得到布尔结果的其他方法吗?

Can you tell me some other method that I can get a boolean result when I delete data from database?

推荐答案

delete 之前，laravel 有几个方法.

Before delete , there are several methods in laravel.

User::find(1) 和 User::first() 返回一个实例.

User::find(1) and User::first() return an instance.

User::where('id',1)->get 和 User::all() 返回一个实例集合.

User::where('id',1)->get and User::all() return a collection of instance.

在模型实例上调用 delete 将返回 true/false

call delete on an model instance will returns true/false

$user=User::find(1);
$user->delete(); //returns true/false

对实例集合调用 delete 将返回一个数字，表示已删除的记录数

call delete on a collection of instance will returns a number which represents the number of the records had been deleted

//assume you have 10 users, id from 1 to 10;
$result=User::where('id','<',11)->delete(); //returns 11 (the number of the records had been deleted)

//lets call delete again
$result2=User::where('id','<',11)->delete(); //returns 0 (we have already delete the id<11 users, so this time we delete nothing, the result should be the number of the records had been deleted(0)  ) 

还有其他删除方法，你可以调用destroy作为模型静态方法，如下所示

Also there are other delete methods, you can call destroy as a model static method like below

$result=User::destroy(1,2,3);
$result=User::destroy([1,2,3]);
$result=User::destroy(collect([1, 2, 3]));
//these 3 statement do the same thing, delete id =1,2,3 users, returns the number of the records had been deleted

还有一点，如果你是 laravel 的新手，你可以使用 php artisan tinker 来查看结果，这样效率更高，然后 dd($result) , print_r($result);

One more thing ,if you are new to laravel ,you can use php artisan tinker to see the result, which is more efficient and then dd($result) , print_r($result);

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