Asp.Net Identity - IUserStore FindByNameAsync Custom Method

Question

I want to override the method IUserStore FindByNameAsync. The method is used in the CreateAsyncclass method UserManager. If I return the instance IdentityUserfrom the method, it works fine, but if I return null(for example, there is no user with this username), I got:

{"Message": "An error occurred.", "ExceptionMessage": "The reference to the object is not installed in the object instance.", "ExceptionType": "System.NullReferenceException", "StackTrace": "at Microsoft.AspNet.Identity .UserValidator`2. ValidateUserName d__4.MoveNext ()

This is my override method.

public Task<MyUser> FindByNameAsync(string userName)
{
    return null;
}

I think it does not work in the UserValidatorclass method - ValidateUserNamein the code snippet below.

else
{
    var owner = await Manager.FindByNameAsync(user.UserName).WithCurrentCulture();
    if (owner != null && !EqualityComparer<TKey>.Default.Equals(owner.Id, user.Id))
    {
        errors.Add(String.Format(CultureInfo.CurrentCulture, Resources.DuplicateName, user.UserName));
    }
}

FindByNameAsync, ?

Answer 1

, . . , , - , null. null, ( await Task.Result), NullReferenceException.

public Task<MyUser> FindByNameAsync(string userName)
{
    return Task.FromResult((MyUser)null);
}