Laravel HasMany: Load Only Specific Fields But Don't Skip xxxxx_id

Laravel 2-in-1 quick tip about hasMany relationships.

Let's imagine that you have this Model method:

app/Models/City.php:

class City extends Model {
    public function restaurants()
    {
        return $this->hasMany(Restaurant::class);
    }
}

Then you may load cities with all their restaurants, like this:

City::with('restaurants')->get();

But what if you don't want to load ALL the fields of the restaurant, to save some memory and bandwidth? You can do this:

City::with('restaurants:id,city_id,name')->get();

But be careful. If you skip the RELATIONSHIP column, it will not give you the data at all:

City::with('restaurants:id,name')->get();

This will return NO restaurants.