redirect - ASP.NET MVC Login ReturnUrl always NULL?

Question

Using Forms Authentication in ASP.NET MVC when trying to log back into a site, it puts a ReturnUrl parameter in the query string. My Logon action method accepts a "returnUrl" string. However it seems that returnUrl string is always null, even when it is clearly in the query string. Any thoughts on why this might be the case or a possible fix?

Answer 1

This tends to happen when you're using one generic logon form, but you're explicitly specifying the Controller and ActionMethod (which is causing a form post, but losing the querystring)

Just to clarify, this is what your code should look like in your BeginForm:

Html.BeginForm("LogOn", "Account", new { ReturnUrl = Request.QueryString["ReturnUrl"] })

EDIT: This is by design as RickAnd mentions in comments below. However it doesn't allow for the UI pattern of being deep in a site, clicking on LogOn, then returning to the page you were previously on, if it allows anonymous users. It's a commonly requested pattern. David Allen's approach to LogOff would also work nicely for a clean redirect at LogOn.