php - 在 Laravel 中获取 "Integrity constraint violation: 1452"

Question

我正在使用两个数据透视表来存储表的两个不同关系。一个关系在插入时工作正常。但下一个抛出以下错误。我不知道是什么原因造成的。

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (sdesk.approvers, CONSTRAINT approvers_user_id_foreign FOREIGN KEY (user_id) REFERENCES users (id)) (SQL: insert into approvers (user_id, request_id, updated_at, created_at) values (2, 6, 2014-04-29 10:54:37, 2014-04-29 10:54:37))

这是我的代码:

UrequestsController.php

 public function postCreate() { 
    $request = new Urequest;
    $request->vms = Input::get('vms');
    $request->location = Input::get('location');
    $request->descr = Input::get('descr');
    $request->status = Input::get('status');
    //$request->role_group = Input::get('team');
    $request->save();

    $ruser = new Ruser;
    $ruser->user_id = Input::get('userid');
    $ruser->urequest()->associate($request);
    $ruser->save();

    $approver = new Approver;
    $approver->user_id = Input::get('aid');
    $approver->urequest()->associate($request);
    $approver->save();


    return Redirect::to('users/dashboard')->with('message', 'Saved!');
}

Approver.php

 class Approver extends Eloquent {


protected $fillable = array('request_id', 'user_id');


public function urequest() {
    return $this->belongsTo('Urequest','request_id'); 
}

 }

Ruser.php

 class Ruser extends Eloquent {


protected $fillable = array('request_id', 'user_id');


public function urequest() {
    return $this->belongsTo('Urequest','request_id');
}

 }

urequest.php

 class Urequest extends Eloquent {

protected $table = 'requests';
protected $fillable = array('vms', 'location', 'descr', 'status');

public function ruser() {
    return $this->hasOne('Ruser'); 
}

public function approver() {
    return $this->hasOne('Approver'); 
}

 } 

架构

 Schema::create('requests', function($table)
{
            $table->increments('id');
            $table->string('vms', 20);
            $table->string('location', 20);
                    $table->string('descr', 255);
            $table->string('status', 20);
            $table->timestamps();
        });

 Schema::create('rusers', function($table)
    {
        $table->increments('id');
        $table->integer('request_id')->unsigned();
        $table->foreign('request_id')->references('id')->on('requests');
        $table->integer('user_id')->unsigned();
        $table->foreign('user_id')->references('id')->on('users');
        $table->timestamps();
    });

  Schema::create('approvers', function($table)
    {
        $table->increments('id');
        $table->integer('request_id')->unsigned();
        $table->foreign('request_id')->references('id')->on('requests');
        $table->integer('user_id')->unsigned();
        $table->foreign('user_id')->references('id')->on('users');
        $table->timestamps();
    });

Answer 1

当您在外表中插入/更新的值没有一行时，“外键约束”通常会失败。

在这种情况下，您可能在用户表中没有 user_id 2 或在请求表中没有 request_id 6。

EDIT 刚刚看到 morawcik 在评论中回答了它。