I’m not sure if what I’m doing is actually the right way to create a “user control” in ASP.NET MVC, but it’s worth sharing this tidbit either way. Instead of using a MVC View User Control to create a hidden field, a text box, two anchors, and three JavaScript functions, I chose to put it all in a HtmlHelper in which I write out the HTML and JavaScript myself. Everything worked fine except the almost magical auto-repopulating of the hidden and text fields after a post that didn’t work as expected as in a typical MVC View Page.

The situation: I have a page that needs to be called as a popup from many pages in my MVC application. The page allows single or multiple selection of “items” driven by an XML file. In the event that one day, almost always immediately, I have two or more of these “controls” on one view page, I need the two fields and the three JavaScript functions to have unique names so they don’t cross paths and cause unexpected behavior. I had an ASP.NET User Control to do this in plain old ASP.NET (POAN) since v1.1, and I can’t live without it.

The confusion: If I were to place the hidden, textbox, anchors, and JavaScript functions directly in the calling page, something magical happens after a post. If the controls had values before the post, they appear to magically retain there values after the post. It wasn’t until a colleague of mine, Sat, and I dug into Reflector for a while did we realize what was happening. Html.TextBox, Html.Hidden, and others all do something similar to auto-magically re-populate their values after the post. Since I’m writing out my fields as <input type=”hidden”/> and <input type=”text”/>, the magic doesn’t happen.

      NOTE: The magic will also not happen if you just write <input type=”text”/> on the page. It only happens if you use Html.TextBox.

The solution: I am still new to MVC and still trying to wrap my head around the “right way” to do things. Reflector showed that the HtmlHelpers all looked at the ModelState in the ViewData before rendering their HTML. They looked for their value by key (key being the control/tag name), and, if present, used that as the control/tag’s value. Bing! Maybe I should do the same thing. So just before I go to town with TagBuilder to assemble my controls/tags, I look in the ViewData’s ModelState for my value. If it is there, it must have been posted there by me (my control).

Works like a charm! Now my hidden, textbox, two anchors, and three JavaScript functions are bundled nicely inside of an HtmlHelper class that looks and feels like I’m using a built-in ASP.NET MVC HtmlHelper class. Most importantly, I have the pleasure of typing only this on all my consuming pages.

In a previous post about the AJAX Extensions, I detailed the copy commands to retrieve the DLLs from the GAC. Same thing, this time for the ASP.NET 3.5 Extensions. If you are demoing CTP material in a hosted environment, you will likely need these in your app's bin to avoid the inevitable configuration error.

copy "C:\WINDOWS\assembly\GAC_MSIL\System.Web.Extensions\3.6.0.0__31bf3856ad364e35" C:\dev\MMVCApp\bin
copy "C:\WINDOWS\assembly\GAC_MSIL\System.Web.Extensions.Design\3.6.0.0__31bf3856ad364e35" C:\dev\MMVCApp\bin

A great series of blog posts by Scott Guthrie about the ASP.NET MVC Framework coming soon as part of the ASP.NET 3.5 Extensions release.

Upon hearing the news, a few friends started questioning its intent, usefulness, and longevity. Many of us have been using or contemplating conversion to the MVP pattern, most recently using WCSF. The recent split of the MVP pattern by Fowler has caused many believers to question their faith. While many are still "proving" MVP, MVC has been around for nearly 30 years. Some believe that MVP and MVC can co-exist. Here is a comparison of MVP and MVC that concludes by painting an optimistic picture of MVP and MVC contributing to each other.

ASP.NET MVC appears to be the answer to my unit testing, REST, and code separation prayers. Thank you ScottGu and team!

Check it out!