mysql - 无法存储新行 - SQLSTATE [23000] : Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails

Question

我的客户表和用户表是我的业务表的子表。因此 clients 和 users 表都包含一个 business_id 列，该列引用 businesses 表的 id 列:

public function up()
{
    Schema::create('clients', function(Blueprint $table)
    {
        $table->increments('id');
        $table->integer('business_id')->unsigned();
        $table->foreign('business_id')->references('id')->on('businesses');
        $table->string('first_name');
        $table->string('last_name');
        Etc…

我能够存储一个新用户，它工作正常，但是当我试图将一个新行存储到我的客户表中时，我总是收到这个错误:

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (laravel.clients, CONSTRAINT clients_business_id_foreign FOREIGN KEY (business_id)

Client.php模型

/**
 * The attributes that are mass assignable.
 *
 * @var array
 */
protected $fillable = ['business_id', 'first_name', 'last_name'];

/**
 * Business where this user works.
 * 
 * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
 */
public function businesses()
{
    return $this->belongsTo('App\Business');
}

Business.php 模型

/**
 * Clients that use this business.
 * 
 * @return \Illuminate\Database\Eloquent\Relations\HasMany
 */ 
public function clients()
{
    return $this->hasMany('App\Client','business_id');
}

客户端 Controller .php

public function store(ClientsRequest $request)
{
    var_dump(Auth::user()->business_id);

    $clientinfo = Request::all();

    Client::create($clientinfo);

    $client = new Client;
    $client->business_id = Auth::user()->business_id;
    $client->first_name = $clientinfo['first_name'];
    $client->last_name = $clientinfo['last_name'];

    //$client->save();
    $business->clients()->save($client);

    $last_inserted_id = $data->id;

    return redirect('clients/'.$last_inserted_id.'/edit');

我唯一不确定的是我通过 Auth 检索 business_id(从用户表)的方式。当我 var_dump 该值时，我得到:

string(1) "7"

我知道我的 businesses 表中的 id 值是 7，这就是我要查找的值，但不确定是否应将其转换为整数。

而且，不确定我是否必须使用 :

来保存

 $client->save();

或者

 $business->clients()->save($client);

谢谢

Answer 1

下面两种都是正确的方法，但是第一种比后面的更像Laravel，

public function store(ClientsRequest $request)
{
    $client = new Client([
        'first_name' => $request->get('first_name'),
        'last_name'  => $request->get('last_name'),
    ]);

    $client = Business::findOrFail(Auth::user()->business_id)
              ->clients()
              ->save($client);

    return redirect('clients/'.$client->id.'/edit');
}

附言上面的 business_id 会被 Eloquent

自动添加到 client

其他方式与您所做的一样，您手动插入 business_id。

public function store(ClientsRequest $request)
{
    $clientinfo = Request::all();

    $client = Client::create([
    'business_id' => Auth::user()->business_id;
    'first_name' => $clientinfo['first_name'];
    'last_name' => $clientinfo['last_name'];
    ]);

    return redirect('clients/'.$client->id.'/edit');
}

由于代码中的以下语句，您收到错误消息，

Client::create($clientinfo);

上面的语句将尝试创建一个没有 business_id 的数据库条目，它是一个外键，应该提供但没有提供，因此出错。

而且您不必担心 int<->string 之间的类型转换，PHP 非常擅长。

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