Laravel have Two foreign Key from the same table

Question

Hi I am not very good with Database Design so I would like to know if it's possible to create a table with two foreign key from the same table.

this is my effort on trying to show the relationship

is it possible for me to do this using laravel migration I have tried but it's not working

Schema::create('events', function (Blueprint $table) {
        $table->increments('event_id');
        $table->integer('book_id')->unsigned();
        $table->integer('buyers_id')->unsigned();
        $table->integer('seller_id')->unsigned();
        $table->integer('status')->default(1);
        $table->timestamps();

        $table->foreign('book_id')->references('id')
        ->on('books')
        ->onDelete('cascade')
        ->onUpdate('cascade');
        $table->foreign('buyers_id')->references('id')
        ->on('users')
        ->onDelete('cascade')
        ->onUpdate('cascade');
        $table->foreign('seller_id')->references('id')
        ->on('users')
        ->onDelete('cascade')
        ->onUpdate('cascade');
    });

so the event table will have 3 FK

• one FK from Books

• two FK from Users

   Schema::create('users', function (Blueprint $table) {
      $table->increments('id');
  
      $table->string('name')->unsigned();
  
      $table->integer('user_type');
  
      $table->integer('password');
  
      $table->timestamps();
  
  
  });
  

this is the schema of users table

Answer 1

If in your application your User can act both as a seller and a buyer, the role_id solution proposed in the comments of your quest will not work for you.

Following the solution you were already working on, it not seems to have anything wrong with your migrations, when you run php artisan migrate is it showing any error? If you post it, I can update this part of my response.

In the Event model, you have to describe the relationships like this:

public function buyer()
{
    return $this->belongsTo(User::class, 'buyers_id');
}

public function seller()
{
    return $this->belongsTo(User::class, 'seller_id');
}

So when you use your Event model, you can do it like this

$event = new Event;
$event->buyers_id = 1; // supposing there's a user with id 1
$event->seller_id = 2; // supposing there's a user with id 2
$event->save();

$event->buyer;
# => <User::class id=1>
$event->seller;
# => <User::class id=2>

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[UPDATE] Add a little tip

Not related to your question, but I suggest you rename your buyers_id column to buyer_id. It's a common practice to keep your foreign keys name in the singular in Laravel.

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[UPDATE] Link to the docs

For full documentation on the relationship' methods.

– https://laravel.com/docs/5.7/eloquent-relationships#one-to-many-inverse