How to fix 1048 Column 'user_id' cannot be null in Laravel

How to fix 1048 Column ‘user_id’ cannot be null in Laravel

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Working with robust applications built in Laravel framework starts throwing errors which happens because of missing minor things. One of the common error is 1048 Column ‘user_id’ cannot be null when trying to assign role to existing user. Lets explain this with a code example.

Code Example: A column cannot be null

Lets have a scenario, where we want to assign role to a user. We have this user exists in our database. For this, we will need three things

  1. Route
  2. Form
  3. Controller

Route:

In below route, we are defining a path ‘/users/attach’ and pointing it to a controller method attach. We are naming this route as user.role.attach

Route::put('/users/attach', [App\Http\Controllers\UserController::class, 
'attach'])->name('user.role.attach');

Form:

Now, in blade.php file, we will create a form like below, where action attribute will call on the route name user.role.attach, which is pointing to method attach() in the controller. In the form, we are passing a role which carries role id.

<form method="post" action="{{route('user.role.attach', $user)}}">
 @csrf
 @method('PUT')
 <input type="hidden" name="role" value="{{$role->id}}">
 <button class="btn btn-primary">Attach</button>
</form>

Controller:

In below controller we have following methods, one of them is attach(User $user), now the values inside attach() method which is User $user is expecting a value from the route. our above defined route is ‘/users/attach’

public function show(User $user) {
    return view('admin.users.profile', [
        'user' => $user,
        'roles' => Role::all(), 
    ]);
}

public function attach(User $user) {
  $user->roles()->attach(request('role'));
  return back();
}

If we run our application it will start throwing following error, because there is not value in route path ‘/users/attach’

1048 Column 'user_id' cannot be null when trying to assign role to existing user

This error happens because in Controller method attach() we are expecting user details (user_id). If method do not find user_id, it will throw error.

Solution to Column cannot be null:

We can adjust our route to pass user id {}, so we can we can receive it in our controller and assign a role to specified user.

Route::put('/users/{user}/attach', [App\Http\Controllers\UserController::class, 
'attach'])->name('user.role.attach');

You can of course modify a little bit your route but most important thing here is that you expect User in controller but you didn’t bind in route 😉

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