pass model to view and back to a new controller - asp.net-mvc

Question

I have made a password reset controller that takes in a GUID querystring. As you can see in the below code, my controller checks if the GUID value exists in my db, whereafter it returns user to the view with the attributes name and userId.
[HttpGet]
public ActionResult RetreivePass(string ac)
{
MySqlContext db = new MySqlContext();
PwRetreival PwRetreival = new PwRetreival();
Users user = new Users();
if (db.PwRetreival.FirstOrDefault(u => u.Token == ac) != null)
{
PwRetreival.uId = db.PwRetreival.Where(u => u.Token == ac).Select(u => u.uId).First();
var Attributes = db.Users.Where(u => u.UserId == PwRetreival.uId).Select(u => new { u.Name, u.UserId }).FirstOrDefault();
user.Name = Attributes.Name;
user.UserId = Attributes.UserId;
return View(user);
}
return RedirectToAction("Index", "Home");
}
In my view, it looks like this:
<p>Hello #Model.Name</p>
#using (Html.BeginForm(FormMethod.Post))
{
<p>Change password</p>
#Html.TextBoxFor(u => u.Password)
<p>
<button type="submit">Register</button>
</p>
}
And finally, upon submit, i call this controller:
[HttpPost]
public string RetreivePass(Users model)
{
//Some code here
}
Unfortunately, my issue is, that the parameters (Name & UserId) are not returned with the model to the controller on submit. Therefore i only have the password, which i can't use for anything, because i cant tell my controller where to put the updated password.
Am i missing something??
For convenience, my models are as follows:
public class Users
{
[Key]
public int UserId { get; set; }
public string Email { get; set; }
public string Password { get; set; }
public string Name { get; set; }
public short EmailConfirmed { get; set; }
}
public class PwRetreival
{
[Key]
public int Id { get; set; }
public int uId { get; set; } //FK to Users.UserId
public string Token { get; set; }
}

Answer 1

Make sure you include the name into the form as some input parameter (hidden if the user is not supposed to modify it):
#using (Html.BeginForm(FormMethod.Post))
{
<p>Change password</p>
#Html.HiddenFor(u => u.UserId)
#Html.TextBoxFor(u => u.Password)
<p>
<button type="submit">Register</button>
</p>
}
So basically all parameters that you hope to retrieve when you postback must be included either as input fields inside your form or as query string parameters.
Of course you realize that a hidden field or a query string parameter can be modified from the outside making it quite insecure. Anyone knowing the UserId of another user could trigger a password reset for him. In order to make a secure password reset functionality you might need some cryptography involved. For example you could use a symmetric cryptographic algorithm to encrypt the UserId and send the encrypted value to the client in the password reset email. Then when the form is POSTed back the encrypted value could be decrypted on the server to extract the original client id and the new password. If the encrypted value has been tampered with you will know that immediately.
Another approach would be to generate some token on the server which will be associated with your user and stored in your backend. Then send this token to the client in the password reset email and when POSTed back you will know who the original user was by looking at your backend. It is also a good idea to sign this token using a server secret to ensure that it hasn't been tampered with.