php - 如何在 Laravel 5.1 Integrity constraint violation : 1452? 中添加外键

Question

我正在向 Tickets 表添加一个外键。另一个表是 ticket_statuses。

在 artisan 中，我执行了这个命令:php artisan make:migration add_ticket_status_to_tickets_table

这是迁移文件中的代码:

      class AddTicketStatusToTicketsTable extends Migration
    {
        /**
         * Run the migrations.
         *
         * @return void
         */
        public function up()
        {

            Schema::table('tickets', function ($table) {
                $table->integer('ticket_status_id')->unsigned();
                $table->foreign('ticket_status_id')->references('id')->on('ticket_statuses')->onDelete('cascade');
            });

        }
     }

在那之后，我尝试建立关系。这是我在 Tickets 模型 中的代码:

class Ticket extends Model
{

    // Ticket __belongs_to__ Ticket Status
    public function ticket_status()
    {
        return $this->belongsTo('App\TicketStatus');
    }
}

在 artisan 中，我执行了 php artisan migrate 但是我遇到错误

[Illuminate\Database\QueryException]
  SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`idealcrmalphadb`.`#sql-4ea_1ce`, CONSTRAINT `tickets_ticket_status_id_foreign` FOREIGN KEY (`ticket_status_id`) REFERENCES `tickets` (`id`) ON DELETE CASCADE) (SQL: alter table `tickets` add constraint tickets_ticket_status_id_foreign foreignkey (`ticket_status_id`) references `tickets` (`id`) on delete cascade)

 [PDOException]
  SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`idealcrmalphadb`.`#sql-4ea_1ce`, CONSTRAINT `tickets_ticket_status_id_foreign` FOREIGN KEY (`ticket_status_id`) REFERENCES `tickets` (`id`) ON DELETE CASCADE)

我在模型部分弄错了吗？请帮忙

Answer 1

检查你的迁移表名和引用表名。你这里有误。

更新:

看来您的门票表中已有数据。如果是这样，你现在就可以试试

$table->integer('ticket_status_id')->unsigned()->nullable();