John Davidson

Message:

I'm new to Laravel, and trying to save the Car with a specific Wheels as follows;

$wheel1=new Wheel();

$wheel1->save();



$wheel2=new Wheel();

$wheel2->save();



$car= new Car();            

$car->name='Mazda';

$car->wheelid_1='1';                    

$car->wheelid_2='2';



$car->save();

The problem I'm having is, I need to save the car, wheel1, and wheel2 objects at the same time without referring to or knowing their id's. But I have no wheelid_1 and wheelid_2 until I save the wheel1 and wheel2 first.

I referred this, this and other similar questions but was unable to figure out how to assign wheel1 and wheel2 as new related objects to the car model.

I have done similar tasks using Entity Framework, by just assigning child objects to relevant properties of the parent object with C#. Can I use a similar method in Eloquent?

I have added foreign keys for Wheels and Car on the table creation.

How can I make the reference between all these 03 objects without using their ids for saving?

What I can imagine is something like the below;

$wheel1=new Wheel();

$wheel2=new Wheel();



$car= new Car();            

$car->name='Mazda';

$car->wheel1=$wheel1;                    

$car->wheel2=$wheel2;



$car->save();

Any help would be highly appreciated.

---

My Answer:
In Laravel Eloquent, you can use relationships to define the connection between different models. In your case, you can define a "hasMany" relationship between Car and Wheel models.

First, make sure you have defined the relationship in your models. In your Car model, you can define the relationship like this:

php
class Car extends Model
{
public function wheels()
{
return $this->hasMany(Wheel::class);
}
}


And in your Wheel model, you can define the relationship like this:

php
class Wheel extends Model
{
public function car()
{
return $this->belongsTo(Car::class);
}
}


Then, you can create and save the Car and related Wheels like this:

php
$car = new Car();
$car->name = 'Mazda';
$car->save();

$wheel1 = new Wheel();
$wheel1->car_id = $car->id; // Set the foreign key
$wheel1->save();

$wheel2 = new Wheel();
$wheel2->car_id = $car->id; // Set the foreign key
$wheel2->save();


This way, you are creating the Car object first, saving it to get the id, and then creating the Wheel objects and setting the foreign key to the Car id. This will establish the relationship between the Car and Wheels.

You can also simplify the process by using the "associate" method provided by Eloquent:

php
$car = new Car();
$car->name = 'Mazda';
$car->save();

$wheel1 = new Wheel();
$wheel2 = new Wheel();

$car->wheels()->saveMany([$wheel1, $wheel2]);


This will automatically set the foreign key for the Wheels and save them with the Car.