Laravel 无法更新或删除父行，外键约束失败

Question

我正在尝试运行命令 php artisan migrate:rollback 并抛出错误无法更新或删除父行外键约束失败

现在当我运行命令 php artisan migrate 时出现问题，它成功迁移了我的所有表，但是当我运行回滚命令时，它向我抛出错误，错误是我的 purpose_of_visits 迁移

    public function up()
{
    Schema::create('purpose_of_visits', function (Blueprint $table) {
        $table->increments('id');
        $table->string('purpose', 100);
        $table->string('description', 197);
        $table->integer('speciality_id')->unsigned()->nullable();
        $table->timestamp('created_at')->useCurrent();
        $table->timestamp('updated_at')->useCurrent();
        $table->softDeletes();
        $table->integer('created_by')->unsigned()->nullable();
        $table->integer('updated_by')->unsigned()->nullable();

        $table->foreign('speciality_id')->references('id')->on('specialities')->onDelete('cascade');
        $table->foreign('created_by')->references('id')->on('users')->onDelete('cascade');
        $table->foreign('updated_by')->references('id')->on('users')->onDelete('cascade');
    });
}

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

和我的专业迁移：

    public function up()
{
    Schema::create('specialities', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name', 50);
        $table->string('description',250)->nullable();
        $table->timestamp('created_at')->useCurrent();
        $table->timestamp('updated_at')->useCurrent();
        $table->softDeletes();
        $table->integer('created_by')->unsigned()->nullable();
        $table->integer('updated_by')->unsigned()->nullable();

        $table->foreign('created_by')->references('id')->on('users')->onDelete('cascade');
        $table->foreign('updated_by')->references('id')->on('users')->onDelete('cascade');
    });
}

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

即使我正在使用 onDelete('cascade')，我也无法弄清楚问题出在哪里 非常感谢您的帮助！

Answer 1

确保您的 purpose_of_visits 模型的可填充属性中有 speciality_id、created_by 和 updated_by。 See docs here.

例如在您的模型上。

protected $fillable = ['speciality_id','created_by','updated_by'];

Answer 2

在删除表之前删除表的外键约束。

public function down()
{
    Schema::table('purpose_of_visits', function (Blueprint $table) {
        $table->dropForeign(['speciality_id']);
        $table->dropForeign(['created_by']);
        $table->dropForeign(['updated_by']);
    });
    Schema::dropIfExists('purpose_of_visits');
}

Answer 3

抱歉回复晚了有两种情况会抛出这个错误

例如： 我有posts, authors等表

这是我的post 表迁移

<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreatePostsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('posts', function (Blueprint $table) {
            $table->increments('id');
            $table->string('title');
            $table->text('body');
            $table->unsignedInteger('author_id');
            $table->foreign('author_id')->references('id')->on('authors')->onDelete('cascade');
            $table->timestamps();
        });
    }
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('posts');
    }
}

这是我的authors 表迁移

<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateAuthorsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('authors', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->timestamps();
        });
    }
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('authors');
    }
}

Situation 1:

现在如果posts 表迁移在authors 表迁移之前运行，我会抛出错误

情况2：

在某些情况下，如果你错过了unsigned，它可能会抛出错误

Solution1:

使用

$table->unsignedInteger('speciality_id');
$table->unsignedInteger('speciality_id');
                $table->foreign('author_id')->references('id')->on('specialities')->onDelete('cascade');

而不是这个

$table->integer('speciality_id')->unsigned()->nullable();
$table->foreign('speciality_id')->references('id')->on('specialities')->onDelete('cascade');

如果再次失败，请使用此

try composer dumpautoload

然后 Schema::disableForeignKeyConstraints();

迁移之初

最后

Schema::enableForeignKeyConstraints();

例如：您的迁移可能看起来像

public function up()
    {
    Schema::disableForeignKeyConstraints();
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->string('email')->unique();
            $table->timestamp('email_verified_at')->nullable();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
            $table->softDeletes();
        });

Schema::enableForeignKeyConstraints();
    }

如果出现同样的错误，请附上错误截图并在下方评论

希望对你有帮助