In page One.aspx I have     In web form Two’s page load I call a user-defined function (MakeLinks()) to generate a dynamically-sized set of links to put across the top of the page for Two.aspx. (There might be 3 links, there might be 15: Go To Page: [u]01</u> [u]02</u> 03 [u]04</u> [u]05</u> The current page [03 in this case] is represented, but is not a link.)

I use some data from Session, and some from the Request to create these links. I need these links to have Two.aspx as the target of the href. In VB6 I would have used URLFor(Two) to obtain the reference to Two.aspx.
In .NET I have not been able to find any way to accomplish this.

The .URL property of the Request is One.aspx, since that is who received the actual request...

I don’t want to hard-code it, because I want the app to be capable of being moved without it becoming broken...

How can this be done?

While it would be a very nice feature to have in .NET it seems to make sense that there is no method that will generate a URL for you to a page. Consider that the pages are just ASPX files that can be named anything and can live anywhere in your application structure. They can be derived from any page-derived class in the accessible namespaces (the frame supplied Page class, or any class that you create in your application assemblies that was derived from the system's page class). Therefore, there is no reliable way to say "give me the URL for X".

Something I have started doing to solve two problems at once is to create a shared/static "GetUrl" method on my pages. This method provides the root-relative URL to the page that owns the code-behind class as well as specifying required parameters so you don't have to guess at them or encounter problems later on.

Here's an example:

Public Class ItemAttributes
   Inherits System.Web.UI.Page
   ...
   Public Shared Function GetUrl(itemID As Integer, page As Page) As String
      Return page.ResolveUrl("~/ItemAttributes.aspx?itemID=" & itemID)
   End Function
End Class

This way, if I move this page to another physical directory location I can just change the page name that is resolved in the GetUrl method of the page. Also, if in the future I decide that I need to require another querystring argument on the page's URL I can add it as an argument of the method and force a design/compile-time break that shows me ALL the locations that call it instead of a runtime break that has to be discovered in testing or by a customer (which we don't want).

-Peter

What is the meaning of the tilde in the relative path, and what are you using itemID for?

Because this function is Shared, any process that has ItemAttributes.aspx in scope can get results from this function?
What would be the syntax to cause any given page’s GetURL() to respond (as over against getting a different page’s GetURL() to respond)? Would it just be s = ItemAtributes.GetURL("...")?

The ~ is used as a "home" location placeholder (ala *NIX style). If you use the ~ in a URL on a server control, .NET will replace it with the application root (i.e. "/myWebApplication") so you don't have to hard code server-root-relative URLs for resources. This is typically how you would set up a url for an image used in a user control. You never know where in the file hierarchy of you application the user control will be used (on "index.aspx" or on "folder/folder/folder/another.aspx") so you can't use a pure relative image URL ("images/button.gif") because it will likely break.

The method in the code-behind class is shared so that it's visible by any page in the application despite the class that it lives in not being instantiated. This is so any other page can ask for the URL to the desired page.

For example, we have a page called "itemList.aspx" which shows a list of many items. For each item, we have a hyperlink that will get you to the ItemAttributes page, therefore we call ItemAttributes' GetUrl() method so we can dynamically get the URL to it. In addition, we are told what parameters are required (itemID) by means of the method signature.

-Peter

When I have: the statement Page.ResolveURL(" . . . ") has a squiggle under Page, and hovering shows “Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.”

What am I missing?
Page seems to only have .Equals() and .ReferenceEquals() as available methods, and no properties at all.

As near as I can figure from help, the Page object is not a Shared object, and as such cannot be called from a Shared Method.

Finally, help only lists ResolveURL as part of ASP.NET Mobile controls or under:

I should have described it a bit more. You need to pass a page instance to the method to get a page context.

The ResolveUrl() method does exist. It is possible that it only shows up when you have "Hide Advanced Members" unchecked in Visual Studio preferences.

-Peter