从C＃（.Net 3.5）页面导航时调用方法的方法？

Question

I am working on a project such that once a user is directed to a certain page, they receive a certain level of "authentication" and I wanted to remove this "authentication" if the user tried to navigate away from the page before they completed a form.

I was wondering if the is a way to get a method to call when redirecting away from a specific page that fit into the Page event life cycle (or a different one if you have suggestions)?

I am kind of new to C# and the .Net framework, so if this is not standard, then just tell me what would be the correct approach for this.

Thanks!

Answer 1

You could try using a PageMethod triggered by a JavaScript event. This needs a ScriptManager in the aspx.

Example: JavaScript

function LeavePage(e) {
    PageMethods.RevokeAuthentication();
}

window.onbeforeunload = LeavePage;

C# Code behind

[PageMethod]
public static void RevokeAuthentication()
{
    // Do stuff here
}

However, this method is not foolproof. If the client's browser has scripting disabled the JavaScript will not run.

Perhaps a better method is to handle the authentication in a MasterPage with a Session. A MasterPage is similar to how PHP developers use includes.

Eg OnLoad check page, if pageName allowed higher authentication, set it, else revoke it.

Answer 2

Your page will not know it is being navigated away from as it is effectively stateless. Once the page is generated by the C#, it is transmitted to the browser. The page does not "live" in the C#. Once generated, that's it.

You could use a session variable to track the user's "authentication" level. If they hit other pages, you can check the value of this variable and act accordingly. If they complete the form, you record that fact in the session.

Another option would be to use javascript to callback to the server when the user is leaving the page. This wouldn't act within the Page event life cycle as it will already be complete

Does this "authentication" exist for long? Do you need to persist it?