Concept of laravel first() method

Question

The laravel first() method is pretty straight forward and that's why this question might be silly, but I am not understanding the use of first() method.

Actually, I'm following a youtube tutorial where I am authenticating a user if he has the role of admin then only he will get the access of route otherwise will be redirected to home.

There is no error or issue with code but my understanding.

I am returning the user in User model class function if the user has the role passed by the middleware

Route

Route::get('admin', function (){
     return 'This is Admin page';
})->middleware(['auth', 'auth.admin']);

Middleware

public function handle($request, Closure $next)
{
    if (Auth::user()->hasAnyRole('admin'))
    {
        return $next($request);
    }
    return redirect('home');
}

User Modal

public function hasAnyRole($role)
{
    return null !== $this->roles()->where('name', $role)->first();
}

If I use first() method in hasAnyRole function then only route is protected by other users and only admin get access to the route, If I remove the first() method then all the users get access to route which I don't understand why?

user_9647147 · Answer

According to the docs:

The first method returns the first element in the collection that passes a given truth test:

collect([1, 2, 3, 4])->first(function ($value, $key) {
    return $value > 2;
});
// 3

You may also call the first method with no arguments to get the first element in the collection. If the collection is empty, null is returned:

collect([1, 2, 3, 4])->first();
// 1

In your question, if you don't use the first() method, it will return a collection with no data, like:

Roles {#1
    []
}

This empty collection is not equals to null.

About the !== operator

$x !== $y

It the previous snippet, it returns true if $x is not equal to $y, or they are not of the same type.

So, in your code:

return null !== $this->roles()->where('name', $role)->first();

it will return true if (and only if) the user doesn't have the required role, what you get done by the first() method:

$this->roles()->where('name', 'admin')->first();

If the user doesn't have the admin role, then it returns null, what is identical and same type of null (in your comparison). So it returns false, cause null !== null returns false, and the access is not granted.

If you use something like

$this->roles()->where('name', 'admin');

and the user does not have the admin role, it return something like this:

Roles {#1
    []
}

Now your hasAnyRole function returns true and the access is granted to the user, since the empty collection is not of the same type and also not equals to null;

Docs about the first method.

Concept of laravel first() method

1 Answers