I create a todo app in laravel with vue. I have two tables: users and todos; every user has many todos like this: User.php model:

class User extends Authenticatable {
    protected $fillable = [
        'name', 'email', 'password',
    ];
    public function todos()
    {
        return $this->hasMany(
            Todos::class,
            'user_id',
            'user_id'
        );
    }
}

Todos.php model:

class Todos extends Model
{
    //
    protected $fillable = ['title', 'completed', 'user_id'];

    public function user()
    {
        return $this->belongsTo('App\User');
    }

then I defined this route:

Route::post('/v1/todo', 'todosController@addTodo');

this is my addTodo from todosController:

 public function addTodo(Request $request)
    {
        $uid = Auth::user()->id;
        //dd($uid);

        $todoCreated = new Todos([
            'title' => $request->input('title'),
            'completed' => 0
        ]);
        $user = User::find($uid);
        //dd($user);

        //dd($todoCreated);
        dd($user->todos()->create([
            'title' => $request->input('title'),
            'completed' => 0,
        ]));
}

when I send form data it shows me this error:Illuminate\Database\QueryException SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'user_id' cannot be null (SQL: insert into todos (title, completed, user_id, updated_at, created_at) values (darya, 0, ?, 2020-07-06 12:17:45, 2020-07-06 12:17:45)). I am new in laravel and I appreciate any help!