limiting user to only select items on laravel listbox

Question

I would like to ask for help, please advise how to solve such problems in laravel

how to make an application like a vehicle ticket application, to limit if there are 5 people on car A, then user can not choose car A in listbox (item listbox carA disable) when booking.

I am confused where to start

I am currently thinking of creating 3 tables

users (id, name,car_id, created_at, updated_at) 
cars (id, car_name, created_at, update_at) 

I am confused what should be done to the controller Thank you very much

thanks to all of you, i can start the first step. currently

on the controller

public function create(){
    $list=MCars::all();

    return view('booking/create')->with('sent_list',$list);

}

on the view

<select name="car" value="{{ old('car')}}">
@foreach($sent_list as $a)
  <option value="{{$a->id}}">{{$a->car_name}}</option>
@endforeach
</select>

I want only cars that contain users <5 that appear on the view

maybe i should put this somewhere

SELECT DISTINCT cars.id, cars.car_name, COUNT(users.car_id) from cars INNER JOIN users ON cars.id = users.car_id

Answer 1

The relationship can be like this:

a user belogsTo a car and the car hasMany users

So the Car model class should be:

..
class Car extends Model
{
    public function users()
    {
        return $this->hasMany('App\User');
    }
}

And the User model:

class User extends Model
{
    public function car()
    {
        return $this->belongsTo('App\Car');
    }
}

Eloquent will automatically determine the proper foreign key. So, here Eloquent will assume the foreign key on the User model is car_id. Access the collection of users by accessing the users property.

$users = App\Car::find(1)->users;
foreach ($users as $user) {
    //
}

In the UserController use:

$user = App\User::find(1);
echo $user->car->name;

This is how the Eloquent works!

Now use the custom logic for limit(5).

To retrieve the number of cars as users:

public function getTotalUsersAttribute()
{
    return $this->hasMany('Car')->whereUserId($this->user_id)->count();    
}

And:

if(getTotalUsersAttribute() >= 5) {
    // dismiss this function with an err msg
}
// otherwise add user to car

Find similar cases and solution from the official docs.