php - 如何播种自引用表 Laravel 5.1

Question

如何从同一个表中为一个表添加两个外键，例如消息:

迁移:

    public function up()
    {
        Schema::create('messages', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('to')->unsigned();
            $table->integer('from')->unsigned();
            $table->integer('parent_id')->unsigned()->nullable();
            $table->text('body');
            $table->boolean('status')->default(false);
            $table->timestamps();
        });

        Schema::table('messages', function (Blueprint $table) {
            $table->foreign('to')
                    ->references('id')->on('users')
                    ->onDelete('cascade');

            $table->foreign('from')
                    ->references('id')->on('users')
                    ->onDelete('cascade');

            $table->foreign('parent_id')
                    ->references('id')->on('messages');

        });
    }

模型工厂:

$factory->define(App\Message::class, function($faker) {

    return [
        'body' => $faker->text
        'from' => //user id,
        'to' => //user id,
        'parent_id' => //message id
    ];

});

1. 如何在这里获取用户 ID？
2. 如何获取该 ID 的现有消息行？

Answer 1

$messages = factory(App\Message::class, 20)->create();
$messageIds = DB::table('messages')->lists('id'); // returns array of userids
DB::table('categories')->where('id', $rowid); // where $rowid is the id which you want

完整的解决方案是这样的

class MessagesTableSeeder extends Seeder
{
    public function run()
    {
        // start with some cleanup    
        DB::table('messages')->truncate();
        // Create some App\Message instances...
        $messageCount = 30;
        $messages = factory(App\Message::class, $messageCount)->create();
        $messageIds = DB::table('messages')->lists('id');
        for($i=0; $i<$messageCount - 1; $i++) {
            $randomizedMessageIds = $messageIds;
            shuffle($randomizedMessageIds);
            DB::table('messages')->where('id', $i)->update(['parent_id'=>$randomizedMessageIds[$i]]);
        }
    }
}