Updating a Laravel pivot table when the pivot has a unique field - laravel

Question

I have two models, User and Service, with a ManyToMany relationship. The pivot table has two additional fields, id_code and alias. There may be many relationships between User and Service, but each one is uniquely identified by the field id_code. I need to retrieve a specific record in the pivot table by the id_code, and update the alias for that record only.
My models:
User:
class User extends Authenticatable
{
//All attributes & other functions here...
public function linked_services(){
return $this->belongsToMany(Service::class)
->withPivot('alias', 'id_code')
->withTimestamps();
}
}
Service:
class Service extends Model
{
//All attributes & other functions here...
public function linked_users(){
return $this->belongsToMany(User::class)
->withPivot('alias', 'id_code')
->withTimestamps();
}
}
Service-User migration:
Schema::create('service_user', function (Blueprint $table) {
$table->bigIncrements('id');
$table->unsignedBigInteger('user_id')->nullable();
$table->unsignedBigInteger('service_id');
$table->string('alias', 50)->nullable();
$table->string('id_code', 50);
$table->foreign('user_id')->references('id')->on('users');
$table->foreign('service_id')->references('id')->on('services');
$table->timestamps();
});
In the update function, I get the specific $id_code from a view, but I don't know how to update the "alias" for that specific "id_code".
What I already tried and is not working:
public function update(Request $request, String $id_code){
foreach(Auth::user()->linked_services as $service){
if($service->pivot->id_code === $id_code){
$service->pivot->alias = $request->alias;
$service->pivot->save();
}
}
return redirect()->route('services_user.index');
}
This function updates ALL the existing pivot records for the service_user, I need to update only the specific record for an given "id_code".

Answer 1

I solved it!!! I tell you how:
Auth::user()->linked_services()
->wherePivot('id_code', $id_code)
->update(['alias' => $request->alias]);
I learned that $user->linked_services() (unlike $user->linked_services) returns a relationship object (in this case, belongsToMany), which contains all the relationship data (intermediate table, pivots, FKs, parent / related objects, etc), and the desired pivot can be accessed on that object with ->wherePivot().