Laravel 迁移自引用外键问题

Hi I have a problem to create a table using migration schema builder. The problem occure with table with self referencing foreign key. Here is the code which produce error:

        Schema::create('cb_category', function($table)
    {
        $table->integer('id')->primary()->unique()->unsigned();
        $table->integer('domain_id')->unsigned();
        $table->foreign('domain_id')->references('id')->on('cb_domain'); 
        $table->integer('parent_id')->nullable(); 
        $table->foreign('parent_id')->references('id')->on('cb_category')->onUpdate('cascade')->onDelete('cascade'); 
        $table->string('name');
        $table->integer('level');
    });

这是错误:

  SQLSTATE[HY000]: General error: 1005 Can't create table 'eklik2.#sql-7d4_e' (errno: 150) (SQL: alter table `cb_cate

gory在 del 上添加约束 cb_category_parent_id_foreign 外键 (parent_id) 引用cb_category(id`)更新级联上的级联)(绑定:数组())