Save/retrieve data by foreign key (API) - ios

Question

I'm attempting to set up my API for iOS app. This is my first time to use Laravel as a API so here is what I have in my tables:
Cars
Schema::create('cars', function (Blueprint $table) {
$table->increments('id');
$table->string('name')->nullable();
$table->string('age')->nullable();
$table->string('model')->nullable();
$table->string('color')->nullable();
Users
$table->increments('id');
$table->string('name')->nullable();
$table->string('street')->nullable();
$table->string('niehgborhood')->nullable();
$table->string('city')->nullable();
Contract
$table->increments('id');
$table->integer('user_id')->unsigned;
$table->foreign('user_id')->references('id')->on('users');
$table->integer('car_id')->unsigned;
$table->foreign('car_id')->references('id')->on('cars');
Models
protected $table = 'users';
protected $guarded = ['id'];
protected $fillable = ['phone', 'email',
'street','city','niehgborhood'
,'national_id'];
public function cars()
{
return $this->hasMany('App\User');
}
Users
protected $guarded = ['id'];
protected $fillable = ['name', 'age',
'color, model'
];
public function users()
{
return $this->belongsToMany('App\Cars');
}
in my controller I'm familiar with saving requested data
$user = JWTAuth::parseToken()->authenticate();
$user->phone = $request->phone;
$user->city = $request->city;
$user->save();
my goal with this project is to display the data(contracts) saved by iOS app users in my dashboard. For example, users info and the cars they are interested in my table. Can someone help me with what to do query in the controller(not views). Or provide helpful links for projects like this.

Answer 1

Your relation between User and Cars should be many-to-many. Please read the docs to apply this relation properly.
If your relations are in the place then you can do as:
$user = JWTAuth::parseToken()->authenticate();
$cars = $user->cars; // returns collection of cars associated with the user.
For example - In your User model define the following relation:
public function cars()
{
return $this->belongsToMany('App\Car');
}
Update
To save the user and associate cars, you can do it as following:
$user = JWTAuth::parseToken()->authenticate();
$user->phone = $request->phone;
$user->city = $request->city;
$user->save();
$car_ids = $request->car_ids; // it should return an array
$user->cars()->sync($car_ids);
There is more way to store the data. Please read the docs here for more info.