After we created a one-to-one relationship between the users table and the profiles table, and added the hasOne() method to the User model, and the belongsTo() method to the Profile model, it's time to find out how the data is saved in the database when we use this relationship. And what are the methods used for that?

These methods are divided into three main ways:

1. Without using method profile.
2. By using method profile.
3. By using the inverse method user.

The best method to use depends on the specific needs of your application.
If you only need to save the profile associated with the user, then the first method is the simplest option.
If you need to get, update, or delete the profile, then the second method is a better option.
If you need to get, update, or delete the user, then the third method is a better option.

1. Without using method profile.

• We first go to the routes/web.php file and add a new route so that we can test these method.

use App\Models\Profile;
use App\Models\User;
---
Route::get('/one-to-one', method () {
    $user = User::create(['username' => 'John Doe']);
    Profile::create([
        'user_id' => $user->id,
        'firstname' => 'John',
        'lastname' => 'Doe',
        'birthday' => '08-11-1991'
    ]);
    return response()->json([
        'username' => $user->username,
        'firstname' => $user->profile->firstname,
        'lastname' => $user->profile->lastname,
    ]);
});

• We opened the browser and went to the link http://127.0.0.1:8000/one-to-one. To our satisfaction, the user had been created successfully.

{
  "username": "John Doe",
  "firstname": "John",
  "lastname": "Doe"
}

2. By using method profile.

• We first go to the routes/web.php file and edit this route.

Route::get('/one-to-one', method () {
    $user = User::create(['username' => 'Tom Cruz']);
    $user->profile()->create([
      'firstname' => 'Tom',
      'lastname' => 'Cruz',
      'birthday' => '01-02-2000'
    ]);
    return response()->json([
        'username' => $user->username,
        'firstname' => $user->profile->firstname,
        'lastname' => $user->profile->lastname,
    ]);
});

• We open the browser again and go to this link: http://127.0.0.1:8000/one-to-one to find that the user has been created successfully.

{
  "username": "Tom Cruz",
  "firstname": "Tom",
  "lastname": "Cruz"
}

3. By using the inverse method user.

• We first go to the routes/web.php file and update this route.

Route::get('/one-to-one', method () {
    $user = User::create(['username' => 'Adam Smith']);
    $profile = new Profile([
        'firstname' => 'Adam',
        'lastname' => 'Smith',
        'birthday' => '01-01-1999'
    ]);

    $profile->user()->associate($user)->save();
    return response()->json([
        'username' => $profile->user->username,
        'firstname' => $profile->firstname,
        'lastname' => $profile->lastname,
    ]);
});

• We open the browser again and go to this link: http://127.0.0.1:8000/one-to-one to find that the user has been created successfully.

{
  "username": "Adam Smith",
  "firstname": "Adam",
  "lastname": "Smith"
}

• You can find the repo of this series on github here