Why my ViewModel field becomes empty when the url is HTML encoded?

Question

I am facing a strange issue, sometimes i am getting the url from the sendgrid as

https://localhost:81/Activation?username=ats8@test.com&activationToken=EAAAAA

which works fine. but sometimes i am getting url which is encoded as follows,

"https://localhost:81/Activation?username=ats8%40test.com&activationToken=EAAAAA"

and my ViewModel is as follows,

  public class Verification
    {
        [DataType(DataType.EmailAddress)]
        public string Username { get; set; }

        [Required]
        [DataType(DataType.Password)]
        public string Password { get; set; }

        [Required]
        [DataType(DataType.Password)]
        [Compare("Password")]
        public string ConfirmPassword { get; set; }

        public string ActivationToken { get; set; }

    }

and the Method goes as follows,

 public ActionResult Activation(string username, string activationToken)
        {
            var model = new Verification
            {
                Username = username,
                ActivationToken = activationToken
            };

            return View(model);
        }

on the 2nd case, the activationToken comes as null. how can i detect activationToken even if the url is encoded?

Answer 1

I believe it is not the code you pasted in question which is causing issue. The issue may be somewhere else - probably in the view.

I have tested this code with various combination of HTTP versions / Browsers / .Net / .Net core frameworks and it is working fine.

All I can do right now is to give you pointers on where you can look for an error:

First pointer to look in model binding

While working on this sample I realized, that somewhere in your solution probably model binding is not decoding the email "@" character properly.
Note that this is applicable only if you have written any custom logic to bind the values. I see very less probability that this pointer would help you as the input parameters to action are primitive data types.

Second Pointer To look for what you are doing in view

What i suspect is you are getting username and activation token both appropriately in second URL's case. But when you send your email ID with "%40" instead of "@" character, somehow your view is not rendering properly. This is somehow causing your activationToken to be NULL.

You should first put break-point in action method to check both UserName and ActivationToken parameters are nonempty.

If they are non empty then add HttpUtility.UrlDecode where you are assigning username as shown in below code:

var model = new Verification
{
     Username = HttpUtility.UrlDecode(username),
     ActivationToken = activationCode
};

This would remove %40 from mail and replace it with "@" character.

This second pointer mostly should resolve your issue.