How to have POST ActionHandler return the GET ActionHandler by a custom Attribute?

Our system is MVC2 authenticated by ADFS 2. So when a user clicks on a bookmark for http://www.foo.com/Car/Details/3, this hits our Car controller and calls our Details GET action handler and passes 3 in as the ID (all basic MVC stuff). So we have this ActionHandler decorated with a [Authorize] attribute and have ADFS2 hooked up, so the page then redirects to our auth server which then redirects back to our app, but with a POST (all basic ADFS stuff). The problem is that this redirect is a POST and therefore our Details POST handler is called, but clearly it doesn't have the data I need.

Now I have identified some code that detects this scenario and this code looks something like this:

[Authorize]
[MySpecialHttpGet]
public ActionResult Details(long id)
{
    var model = GetModel(id);
    return View(model);
}

[Authorize]
[MySpecialHttpPost]
public ActionResult Details(long id, ViewModel model)
{
    /***START OF SPECIAL CODE***/
    // If we were posted to by ADFS, redirect to the GET handler.
    if (Request.Form["wa"] != null && Request.Form["wa"].ToLower().Contains("signin"))
    {
        // We were posted to here but need to respond with the GET view.
        return Redirect(Request.Url.AbsoluteUri);
    }
    /***END OF SPECIAL CODE***/

    var result = Something.SaveData(model);
    return result.ActionResultToReturnWith;
}

The problem with this is that I need to do this on every single POST ActionHandler in the app and I really don't want to do that. Given that I already have custom attributes on all of these ActionHandlers, I would like to use those attributes to inject this functionality for me.

Now the MySpecialHttpGet and MySpecialHttpPost are nothing incredibly special that you really need to know about other than they extend ActionMethodSele开发者_开发技巧ctorAttribute. I would LIKE to add code in the MySpecialPost attribute to inject that functionality.

So my question:

How would I add code to perform this kind of check in this Attribute?

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For now, we have not found the solution we wanted and are simply pasting that code (well, a function call with that code in it) at the beginning of EVERY controller.