php - SQLSTATE[23000] : Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails

Question

我知道这是一个常见问题，但不知道这里出了什么问题。如您所见，有这个 //return $user 并且它显示了一个有效的 id。也在数据库中进行了检查。

        $user = new User;
        $user->first_name           = $data['first_name'];
        $user->last_name            = $data['last_name'];
        $user->email                = $data['email'];
        $user->phone_no             = $data['phone_no'];
        $user->created_from         = 'Web App';
        $user->save();
        // return $user;
        Session::put('user_id',$user->id);
        // return $user->id;
        $address = new Address;
        $address->user_id           = $user->id;
        $address->first_name        = $data['receiver_first_name'];
        $address->last_name         = $data['receiver_last_name'];
        $address->email             = $data['receiver_email'];
        $address->address_line_1    = $data['receiver_address_line_1'];
        $address->address_line_2    = $data['receiver_address_line_2'];
        $address->landmark          = $data['receiver_landmark'];
        $address->pincode           = $data['receiver_pincode'];
        $address->phone_no          = $data['receiver_phone_no'];
        $address->created_from      = 'Web App';
        $address->save();

这里是迁移:这是用户迁移

<?php

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUsersTable extends Migration {

/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    Schema::create('users', function($table){
        $table->increments('id');
        $table->string('first_name');
        $table->string('last_name');
        $table->string('email');
        $table->string('phone_no', 20)->nullable();
        $table->string('password')->nullable();
        $table->string('remember_token', 100);
        $table->date('date_of_birth')->nullable();
        $table->string('created_from');

        $table->timestamps();
        $table->softDeletes();
    });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    Schema::dropIfExists('users');
}

地址

public function up()
{
    Schema::create('addresses', function($table){
        $table->increments('id');
        $table->integer('user_id')->unsigned();
        $table->string('first_name');
        $table->string('last_name');
        $table->string('email');
        $table->string('address_line_1');
        $table->string('address_line_2')->nullable();
        $table->string('landmark')->nullable();
        $table->string('city')->nullable();
        $table->string('state')->nullable();
        $table->string('phone_no', 13);
        $table->integer('pincode');
        $table->string('created_from');

        $table->timestamps();
        $table->softDeletes();

        $table->foreign('user_id')->references('id')->on('users');
    });
}

如果有帮助，这里是错误的屏幕截图。

Answer 1

根据报错信息，你的错误是由于在adresses.user_id中插入了一个值(FK to src.id)，而这个值在src.id中是不存在的。
在示例中，您尝试在 adresses.user_id 中插入 29，检查 SELECT id FROM src WHERE id=29 是否返回任何结果。如果不是，那就是你的问题。