UserManager.FindByEmail() returning Null - asp.net-mvc

Question

I'm trying to implement email address based usernames in AspNet.Identity for MVC5. My application works find as long as there is a registered email/username on the system.
I just discovered that if the user does not exist and tries to login an exception gets thrown on Line 72.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
Line 71: //Add this to check if the email was confirmed.
Line 72: var userid = UserManager.FindByEmail(model.Email).Id;
Here is my code.
public async Task<ActionResult> Login(LoginViewModel model, string returnUrl)
{
if (ModelState.IsValid)
{
//Add this to check if the email was confirmed.
var userid = UserManager.FindByEmail(model.Email).Id;
// **Line 72. 'userid' is empty.**
// Here is my attempt but doesn't do anything.
if (string.IsNullOrEmpty(userid)) {
ModelState.AddModelError("","You are not registered!");
}
if (!UserManager.IsEmailConfirmed(userid))
{
ModelState.AddModelError("", "E-mail address has not been confirmed.");
return View(model);
}
}
var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, shouldLockout: false);
switch (result)
{
case SignInStatus.Success:
return RedirectToLocal(returnUrl);
case SignInStatus.LockedOut:
return View("Lockout");
case SignInStatus.RequiresVerification:
return RedirectToAction("SendCode", new { ReturnUrl = returnUrl });
case SignInStatus.Failure:
default:
ModelState.AddModelError("", "Invalid login attempt.");
return View(model);
}
}
Thank you!

Answer 1

I tried the code below and worked for me:
//
// POST: /Account/Login
[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Login(LoginViewModel model, string returnUrl)
{
if (!ModelState.IsValid)
{
return View(model);
}
string userName = ""; // to be used as arg to PasswordSignInAsync
// you'd better declare the appropriate Type.
// using "var" doesn't work here - I don't know why...
ApplicationUser user = await UserManager.FindByEmailAsync(model.UserName);
if (user != null)
{
// found an existing user having the given Email
// so let's get it's UserName to test SignIn
userName = user.UserName;
// just for debugging - check your AspNetUser table
// ModelState.AddModelError("", userName + " ID = " + user.Id.ToString());
}
else
{
// Hum... no email found - perhaps the user is really trying the UserName
// Perhaps Email != UserName
// It's interesting to give the user the option to use Email or UserName
// to get authenticated.
// Let's play, then!
userName = model.UserName;
}
// This doesn't count login failures towards account lockout
// To enable password failures to trigger account lockout, change to shouldLockout: true
var result = await SignInManager.PasswordSignInAsync(userName, model.Password,
model.RememberMe, shouldLockout: true);
// from here on, it's the scaffolded code...
switch (result)
{
case SignInStatus.Success:
return RedirectToLocal(returnUrl);
case SignInStatus.LockedOut:
return View("Lockout");
case SignInStatus.RequiresVerification:
return RedirectToAction("SendCode", new { ReturnUrl = returnUrl, RememberMe = model.RememberMe });
case SignInStatus.Failure:
default:
ModelState.AddModelError("", "Invalid login attempt.");
return View(model);
}
}
Hope it's useful, even after all that time.
Please, let us know if your problem was solved.
Regards.

Answer 2

I added the code below and it works but I still don't understand how FindByNameAsyn() method actually work as opposed to FindByName()? Also
Is there a better way to do this? Thank you!
// Code that works.
var user = await UserManager.FindByNameAsync(model.Email);
if (user == null)
{
ModelState.AddModelError("", "Invalid login attempt.");
return View(model);
}