Laravel 5.2 無法添加外鍵約束

Question

我在migrations表中注冊遷移時遇到問題，運行php artisan migrate時出現以下錯誤：

[Illuminate\Database\QueryException]                                         
SQLSTATE[HY000]: General error: 1215 Cannot add foreign key 
constraint (SQL: alter table `surgeon_surgeon_specialty` add 
constraint `surgeon_surgeon_specialty_surgeon_id_foreign` foreign key 
(`surgeon_id`) references `surgeon` (`id`) on delete cascade)

[PDOException]                                                          
SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint

這是我目前的文件：

Surgeons Table Migration

<?php

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

class CreateSurgeonsTable extends Migration
{
 /**
 * Run the migrations.
 *
 * @return void
 */
 public function up()
 {
    Schema::create('surgeons', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('user_id');
        $table->string('surgeon_name', 30)->unique();
        $table->timestamps();
    });
 }

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

Surgeon Specialties Table Migration

<?php

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

class CreateSurgeonSpecialtiesTable extends Migration
{
 /**
 * Run the migrations.
 *
 * @return void
 */
 public function up()
 {
    Schema::create('surgeon_specialties', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('user_id')->unsigned();
        $table->string('surgeon_specialty_name');
        $table->timestamps();
        $table->unique(['surgeon_specialty_name','user_id']);
    });
 }

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

然后我使用Laravel-5-Generators-Extended包來生成

Surgeon Surgeon Specialty Table Migration

<?php

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

class CreateSurgeonSurgeonSpecialtyPivotTable extends Migration
{
 /**
 * Run the migrations.
 *
 * @return void
 */
 public function up()
 {
    Schema::create('surgeon_surgeon_specialty', function (Blueprint $table) {
        $table->integer('surgeon_id')->unsigned()->index();
        $table->foreign('surgeon_id')->references('id')->on('surgeon')->onDelete('cascade');
        $table->integer('surgeon_specialty_id')->unsigned()->index();
        $table->foreign('surgeon_specialty_id')->references('id')->on('surgeon_specialties')->onDelete('cascade');
        $table->primary(['surgeon_id', 'surgeon_specialty_id']);
    });
 }

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

但是根據朋友的建議將其更改為：

<?php

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

class CreateSurgeonSpecialtiesTable extends Migration
{
 /**
 * Run the migrations.
 *
 * @return void
 */
 public function up()
 {
    Schema::create('surgeon_specialties', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('user_id')->unsigned();
        $table->string('surgeon_specialty_name');
        $table->timestamps();
        $table->unique(['surgeon_specialty_name','user_id']);
    });
 }

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

The table does migrate...

...但是，我仍然收到錯誤消息。 任何幫助將不勝感激。謝謝！

Answer 1

我在 Laravel 8 上遇到過這個問題。我不確定它是否與這篇文章相關。 當您創建的遷移發生這種情況many的前one部分one-to-many的關系。 在您的情況下，我猜您在users之前為items創建了遷移。 只需根據您的關系重命名您的遷移文件。 您的surgeon遷移日期應該早於在surgeon surgeon_surgeon_specialty表之前創建。

另外我建議聲明Surgeon模型的表名：

class Surgeon extends Model {
    public $table = 'surgeons';
}

這是因為我看到 Laravel 無法根據您的模型類確定您的表名。