laravel - 在 Laravel 迁移中删除外键

Question

我在从 Laravel 应用程序中删除一些外键时遇到问题。问题是当我尝试回滚迁移时:

php artisan migrate:rollback

我不知道为什么我在控制台中出现错误:

[Illuminate\Database\QueryException] SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'role_user_user_id_foreign'; check that column/key exists (SQL: alter table role_user drop foreign key role_user_user_id_foreign)

[Doctrine\DBAL\Driver\PDOException] SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'role_user_user_id_foreign'; check that column/key exists

[PDOException] SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'role_user_user_id_foreign'; check that column/key exists

下面我展示了我的迁移类(class):

class UpdateRoleUserTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        schema::table('role_user',function(Blueprint $table){


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

        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('role_user', function (Blueprint $table) {
        $table->dropForeign('role_user_user_id_foreign');
        $table->dropForeign('role_user_role_id_foreign');

    });
    }
}

我在数据库中的表是由迁移类创建的:

class CreateRoleUserTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('role_user', function (Blueprint $table) {

            $table->increments('id');
            $table->integer('user_id')->unsigned();
            $table->integer('role_id')->unsigned();

        });
    }

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

Answer 1

在所有>4.0 版本的 Laravel 中，它允许将列名放入一个数组中，然后它会自行解析。我试图找到随附的文档，但他们似乎已将其排除在外。

在您的更新迁移中，试试这个:

Schema::table('role_user', function (Blueprint $table) {
  $table->dropForeign(['user_id']);
  $table->dropForeign(['role_id']);
});