在Laravel构造函数中将模型链接到父级

Question

Maybe I'm searching it all wrong but I haven't been able to figure out an answer.. Say I have a model Building, which always has n Floor(s)

I would like to write a constructor for Building, in which I could specify a number of Floor(s) to be created. The problem is that I can't link back a Floor to the Building because when the constructor for Building is being called, it doesn't have a primary key yet...

Basically, my code looks like this but doesn't work:

class Building extends Model {
  public function __construct($nbFloors) {
    for($i=0; $i<$nbFloors; $i++) {
       $foo = new Floor();
       $foo->building_id = $this->id;
       $foo->save();
    }
  }
}

What would be the correct solution to achieve something like that?

Answer 1

The primary key will never be available in the constructor and your constructor's definition is not compatible with Model which expects an array of attributes as the first argument.

You're performing too much logic in your constructor, a constructor is meant to just instantiate an object and its dependencies, not perform business logic. By doing this in your constructor, you're actually going to be attempting to create new floors EVERY time your Model is instantiated which includes when your model is retrieved from the database.

I'd recommend adding a new method like:

public function createWithFloors($n) {
    $this->save();
    ...
}

Now, you can use the model as it's expected and call the create method:

$building = new Building(['name' => 'Empire State']);
$building->createWithFloors(102);