如果在 ASP.NET (webforms) / OWIN 中多次单击，则复制用户

Question

I'm creating a user using OWIN. Problem is, while creating an account... I manually check in my database if the user already exists. What is happening quite frequently is, if a user double, triple, or even more clicks it displays them with the "your account has already been made" error, and doesn't automatically redirect them. Furthermore, it creates loads of duplicates of the data I'm saving to another table in SQL which is used for new users signing up.

This is the code that gets executed when the user clicks

 if (!u.userExists(email))
   {
   var created = um.CreateUser(email, email, password, firstName, lastName, country, ip);

   if (created == true)
     {
       u.subscribeSIB(email, firstName, lastName, country);
       Response.RedirectPermanent("/members/");
     }
     else
     {
      ipTop.Text = "<span class=\"text-danger mt-3\">An Error Occured</span>";
     }
       }
      else // acc exists
      {
      ipTop.Text = "<span class=\"text-danger mt-3\">Sorry - it seems you've already made an account before. <a href=\"/login\">Sign In</a>.</span>";
      }

And this is the code that checks if the user exists

    public bool userExists(string email)
   {
    var userStore = new UserStore<IdentityUser>();
    var userManager = new UserManager<IdentityUser>(userStore);
    var useremail = userManager.FindByEmail(email);

    if (useremail == null)
    {
        return false;
    }
    return true;
   }

How should I go about stopping the duplicates, and the multiple triggering?

Answer 1

<asp:Button ID="MyButton" runat="server" CssClass="button" Text="Click Here" OnClientClick="$('.button').hide();" OnClick="MyButton_Click" />

You can do the above, using jquery. The OnClientClick will hide the button on the client side, and then the postback will proceed to the server.