send a mail to a user with a link

Question

Hi everyone, In my project i am sending a mail to the user to create a user account. I want to enable that link for the first time he/she clicks the link. if he clicks the link for more than 2 times,then it should go to custom error page.how to do this?

Answer 1

This depends on how the link is generated. For example: If your link contains a username as GET-parameter, then you could simply query your database if the username is already in use. I would advise against that, because the user can easily change that GET-Parameter

I would recommend this: Your link should contain a unique identifier, most likly a hash. This hash is stored somewhere, to garantee it's uniqueness, like in the usertable of your database (a column for the hash of the registration link). That might also come handy, because you could create new user rows and already prefill them with necessary information. You could use these information upon rendering to insert text into the textboxes