ASP.NET

• Displaying the Number of Active Users on an ASP.NET Site: Scott Mitchell continues his excellent series on ASP.NET’s membership, roles, and profile support.  In this article he discusses how to use ASP.NET’s Membership features to estimate and display the number of active users currently visiting a site.

• ASP.NET Dynamic Data Update: The ASP.NET team last week released an update of the new ASP.NET Dynamic Data feature.  This update adds several new features including cleaner URL support using the same URL routing feature that ASP.NET MVC uses, as well as better confirmation, foreign-key, and template support. 

• ASP.NET Testing with Ivonna: Travis Illig blogs about a new testing framework named Ivonna that enables unit testing of ASP.NET web forms.

ASP.NET AJAX

• ASP.NET AJAX UI Templates: Nikhil Kothari from the ASP.NET team has a cool post that shows off a prototype he has been working on that enables clean client-side AJAX templating of UI. 

• ASP.NET AJAX Control Toolkit TabContainer Theme Gallery: Matt Berseth has another of his excellent posts - this one shows off a bunch of cool themes you can use to style the TabContainer control in the ASP.NET AJAX Control Toolkit.

• Reducing Page Load Times with UpdatePanels and Timers: Paul Glavich posts of a cool trick you can use with tab controls to asynchronously load their content in the background in order to improve perceived page load time.

• Why do ASP.NET AJAX page methods have to be static? Dave Ward has a useful article that talks about the page methods feature in ASP.NET AJAX, and explains why they are static methods.

• JQuery Intellisense in VS 2008: Brad Vincent posts about using the VS 2008 Web Development Hot-Fix we released in February to get a nice JavaScript intellisense experience in Visual Studio 2008 when using the JQuery AJAX library.

ASP.NET MVC

• Inversion of Control, ASP.NET MVC and Unit Testing: Fredrik Kalseth has a cool article that talks about the concepts behind inversion of control (IOC) and how you can use this with ASP.NET MVC to better isolate dependencies and enable better unit testing of your code.

• Stephen Walther’s ASP.NET MVC Talk: Stephen Walther delivered a many-hour ASP.NET MVC post conference talk at ASP.NET Connections last week.  You can download his slides + demos for free.  Also check out his previous posts on Unit Tests with Visual Studio 2008 and TDD with Rhino Mocks.

• MVC Contrib Project Update: Eric Hexter blogs about some of the latest updates to the open source MvcContrib project to work with the latest ASP.NET MVC interim source release.

• Testing Action Results with ASP.NET MVC: Jeremy Skinner blogs about some cool extension method helpers he has added to MvcContrib to enable pretty sweet testing of Controller actions.

• MVC Membership Starter Kit - 1.2 Release: Troy Goode has posted an update to his excellent MVC Membership Starter Kit.  This version works with the interim ASP.NET MVC source release.

Silverlight

• Defining Silverlight DataGrid Columns at Runtime: Scott Morrison from the Silverlight team has a cool blog post that talks about how to define Silverlight DataGrid Columns via code at runtime.  Visit my Silverlight links page for more DataGrid posts.

• Silverlight HTTP Networking Stack (Part 1), (Part 2), (Part 3): Karen Corby from the Silverlight team has a great three part blog series that talks about the new Silverlight 2 networking stack and how cross domain security works with it.

• Pushing Data to a Silverlight Client with Sockets (Part 1) and (Part 2): Dan Wahlin demonstrates how to implement a "GameStream" socket server and connect to it from a Silverlight client using Silverlight 2’s built-in network sockets support. 

• Silverlight - the Song: Spike Xavier and Dan Wahlin have posted another of their unique and special songs.

Hope this helps,

Scott

General Session

The slides for my keynote can be downloaded here. 

In the talk I demonstrated how to debug the .NET Framework source code.  You can learn how to set this up with VS 2008 here. 

I also demonstrated building a site using the new ASP.NET Dynamic Data support - which you can learn more about here.  I also demonstrated using the new ASP.NET MVC Framework - which you can learn more about here.

I also showed off the new Hard Rock Memorabilia site built with Silverlight 2.  You can try out the Hard Rock application yourself here.  You can learn more about Silverlight from my links page here.

Building .NET Applications with Silverlight

The slides + demos for Silverlight breakout talk can be downloaded here.

You can learn more about Silverlight from my links page here.  In particular, I recommend reading my tutorial posts here and here.

ASP.NET MVC

The slides + demos for my ASP.NET MVC talk can be downloaded here.

You can learn more about the latest ASP.NET MVC source refresh here.  Stephen Walther also just posted a really good set of slides + demos from his post conference tutorial on ASP.NET MVC here.

Hope this helps,

Scott

Last month we used it to publish the first drop of the ASP.NET MVC source code.  This first drop included the source for the ASP.NET MVC Preview 2 release that we shipped at MIX, along with Visual Studio project files to enable you to patch and build it yourself.

A few hours ago we published a refresh of the ASP.NET MVC source code on the site.  This source refresh is not an official new ASP.NET MVC preview release - instead it is an interim drop that provides a look at the current state of the source tree.  We will ship the official "ASP.NET MVC Preview 3" release in a few weeks after we finish up some more work (more features and tweaks to existing ones, better VS tool integration, VS express edition support, documentation, etc).  If you are someone who wants a hassle-free installation of ASP.NET MVC to use that ships with documentation and full tool support you’ll probably want to wait for this official preview release.  If you are someone who wants a chance to see an early "preview of the preview" and have the opportunity to start using and giving feedback on some of the features immediately, today’s source refresh is probably interesting to look at.

Improvements with this ASP.NET MVC Source Refresh

This week’s update (which you can download here) includes a number of improvements to ASP.NET MVC.  Some of these include:

• In addition to posting the source code for the ASP.NET MVC framework, we are also posting the source code for the unit tests that we use to test it.  These tests are implemented using MSTest and the open source Moq mocking framework.  A VS 2008 project file for the unit tests is included to make it easy to build and run them locally within your VS 2008 IDE.

• Significantly easier support for testing Controller classes.  You can now unit test common Controller scenarios without having to mock any objects (more details on how this works below).

• Several nice feature additions and usability improvements to the URL routing system (more details below).

Creating a New ASP.NET MVC Project

You can build your own copy of the ASP.NET MVC assemblies by downloading the MVC source and compiling it locally, or alternatively you can download a VS Template package to get a pre-built version of them along with a Visual Studio project template that you can use to quickly build a new ASP.NET MVC Project that uses the latest bits.

After you install the ASP.NET MVC source refresh .VSI template, a new "ASP.NET MVC Application" project template will show up under the "My Templates" section of your "New Project" dialog:

This new "My Templates" version of the MVC project template lives side-by-side with the previous ASP.NET MVC Preview 2 release (which you can see above it in the main project templates section of the dialog).  This allows you to safely create new projects and and use both the latest source version and the last official preview version on the same machine.

When you create a new project using this updated ASP.NET MVC Project template you’ll by default get a project that looks like below:

This new project solution contains one Controller ("HomeController") under the "\Controllers" directory and two View templates ("About" and "Index") under the "\Views\Home" sub-directory.  Both view templates are based on a common master page for the site ("Site.master"), all of whose styles are defined within a "Site.css" file under the "\Content" directory.

When you run the application the built-in web-server will automatically start up and you’ll see the site’s "Home" content:

Clicking the "About us" tab will then display the "About" content:

The "HomeController" class in the project is responsible for handling both of the URLs above and has two action methods like below:

The default "Site.master" template looks for a "Title" value in the ViewData collection and uses it to render the <title> element of the HTML page.  The default "Index" view template looks for a "Message" value and uses it to render the home page’s welcome message.  You can obviously go in and customize these files however you want.

Controller Changes with this ASP.NET MVC Drop

If you were reading the above code closely you might have noticed a few changes with how Controller classes are by default implemented using this new ASP.NET MVC source refresh drop. 

With the ASP.NET MVC Preview 2 release the above HomeController action methods would have instead been implemented like below:

The MVC feature team is experimenting with a few ideas in this week’s drop and are trying out some new ideas:

1. Action methods on Controllers now by default return an "ActionResult" object (instead of void).  This ActionResult object indicates the result from an action (a view to render, a URL to redirect to, another action/route to execute, etc). 

2. The RenderView(), RedirectToAction(), and Redirect() helper methods on the Controller base class now return typed ActionResult objects (which you can further manipulate or return back from action methods).

3. The RenderView() helper method can now be called without having to explicitly pass in the name of the view template to render.  When you omit the template name the RenderView() method will by default use the name of the action method as the name of the view template to render.  So calling "RenderView()" with no parameters inside the "About()" action method is now the same as explicitly writing "RenderView(’About’)".

It is pretty easy to update existing Controller classes built with Preview 2 to use this new pattern (just change void to ActionResult and add a return statement in front of any RenderView or RedirectToAction helper method calls).

Returning ActionResult Objects from Action Methods

So why change Controller action methods to return ActionResult objects by default instead of returning void?  A number of other popular Web-MVC frameworks use the return object approach (including Django, Tapestry and others), and we found for ASP.NET MVC that it brought a few nice benefits:

1. It enables much cleaner and easier unit testing support for Controllers.  You no longer have to mock out methods on the Response object or ViewEngine objects in order to unit test the response behavior of action methods.  Instead, you can simply assert conditions using the ActionResult object returned from calling the Action method within your unit test (see next section below).

2. It can make Controller logic flow intentions a little clearer and more explicit in scenarios where there might be two different outcomes depending on some condition (for example: redirect if condition A is true, otherwise render a view template it is false).  This can make non-trivial controller action method code easier to read and follow.

3. It enables some nice composition scenarios where a FilterActionAttribute can take the result of an action method and modify/transform it before executing it.  For example: a "Browse" action on a ProductCatalog controller might return an RenderActionResult that indicates it wants to render a "List" view of products.  A FilterActionAttribute declaratively set on the controller class could then have a chance to customize the specific "List" view template rendered to be either List-html.aspx or List-xml.aspx depending on the preferred MIME type of the client.  Multiple FilterActionAttributes can also optionally be chained together to flow the results from one to another.

4. It provides a nice extensibility mechanism for people (including ourselves) to add additional features in the future.  New ActionResult types can be easily created by sub-classing the ActionResult base class and overriding the "ExecuteResult" method.  It would be easy to create a "RenderFile()" helper method, for example, that a developer writing an action could call to return a new "FileActionResult" object.

5. It will enable some nice Asynchronous execution scenarios in the future.  Action methods will be able to return an AsyncActionResult object which indicates that they are waiting on a network operation and want to yield back the worker thread so that ASP.NET can use it to execute another request until the network call completes.  This will enable developers to avoid blocking threads on a server, and support very efficient and scalable code.

One of the goals with this interim preview is to give people a chance to play around with this new approach and do real-world app-building and learning with it.

We will also post an alternative Controller base class sample that you can use if you still prefer the previous "void" action return approach.  We deliberately didn’t include this alternative Controller base class in this source refresh drop, though, because we want to encourage folks to give the "ActionResult" return approach a try and send us their app-building feedback on it.

How To Unit Test Controller Action Methods

I mentioned above that the new ActionResult approach can make unit testing controllers much easier (and avoid the need to use mocking for common scenarios).  Let’s walk through an example of this in action.

Consider the simple NumberController class below:

This Controller class has an "IsEvenNumber" action method that takes a number as a URL argument.  The IsEvenNumber action method first checks whether the number is negative - in which case it redirects the user to an error page.  If it is a positive number it determines whether the number is even or odd, and renders a view template that displays an appropriate message:

Writing unit tests for our "IsEvenNumber" action method is pretty easy thanks to the new ActionResult approach.

Below is an example unit test that verifies that the correct Http redirect occurs when a negative number is supplied (for example: /Number/IsEvenNumber/-1):

Notice above how we did not need to mock any objects to test our action method.  Instead we simply instantiated the NumberController class and called the action method directly (passing in a negative number) and assigned the return value to a local "result" variable.  I used the C# "as type" syntax above to cast the "result" variable as a strongly typed "HttpRedirectResult" type.

What is nice about the C# "as" keyword is that it will assign the value as null instead of throwing an exception if the cast fails (for example: if the action method returned a RenderViewResult instead).  This means I can easily add an assertion check in my test to verify that the result is not null in order to verify that an Http redirect happened.  I can then add a second assertion check to verify that the correct redirect URL was specified.

Testing the scenarios where non-zero numbers are passed in is also easy.  To do this we’ll create two test methods - one testing even numbers and one testing odd numbers.  In both tests we’ll assert that a RenderViewResult was returned, and then verify that the correct "Message" string was passed within the ViewData associated with the view:

We can then right click on our NumberControllerTest class inside VS 2008 and choose the "Run Tests" menu item:

This will execute our three unit tests in-memory (no web-server required) and report back on whether our NumberController.IsEvenNumber() action method is performing the right behavior:

Note: with this week’s source drop you still need to use mocking to test the TempData property on Controllers.  Our plan is to not require mocking to test this with the ASP.NET MVC Preview 3 drop in a few weeks.

MapRoute Helper Method

URL routing rules within ASP.NET MVC applications are typically declared within the "RegisterRoutes" method of the Global.asax class.

With ASP.NET MVC Previews 1 and 2 routes were added to the routes collection by instantiating a Route object directly, wiring it up to a MvcRouteHandler class, and then by setting the appropriate properties on it to declare the route rules:

The above code will continue to work going forward.  However, you can also now take advantage of the new "MapRoute" helper method which provides a much simpler syntax to-do the same thing.  Below is the convention-based URL route configured by default when you create a new ASP.NET MVC project (which replaces the code above):

The MapRoute() helper method is overloaded and takes two, three or four parameters (route name, URL syntax, URL parameter default, and URL parameter regular expression constraints). 

You can call MapRoute() as many times as you want to register multiple named routes in the system.  For example, in addition to the default convention rule, we could add a "Products-Browse" named routing rule like below:

We can then refer to this "Products-Browse" rule explicitly within our Controllers and Views when we want to generate a URL to it.  For example, we could use the Html.RouteLink view helper to indicate that we want to link to our "Products-Browse" route and pass it a "Food" category parameter using code in our view template like below:

This view helper would then access the routing system and output an appropriate HTML hyperlink URL like below (note: how it did automatic parameter substitution of the category parameter into the URL using the route rule):

Note: with this week’s source drop you need to pass-in the controller and action parameters (in addition to the Category param) to the Html.RouteLink() helper to resolve the correct route URL to generate.  The ASP.NET MVC Preview 3 drop in a few weeks will not require this, and allow you to use the Html.RouteLink call exactly as I’ve written it above to resolve the route.

Other URL Route Mapping Features

This week’s MVC source drop also supports a bunch of new URL route mapping features.  You can now include "-", ".", ";" or any other characters you want as part of your route rules.

For example, using a "-" separator you can now parse the language and locale values from your URLs separately using a rule like below:

This would pass appropriate "language", "locale", and "category" parameters to the ProductsController.Browse action method when invoked:

Or you can use the "." file extension type at the end of a URL to determine whether to render back the result in either a XML or HTML format:

This would pass both "category" and a "format" parameters to the ProductsController.Browse action method when invoked:

ASP.NET MVC Preview 2 introduced wildcard route rules.  For example, you can indicate in a rule to pass all remaining URI content on as a named parameter to an action method:

This would pass a "contentUrl" parameter to the WikiController.DisplayPage action method when invoked:

These wildcard routes continue to work fine with this week’s preview - and are very useful to look at if you are building a blogging, wiki, cms or other content based system.

Note that in addition to using the new routing system for ASP.NET MVC scenarios, we are also now using the same routing system within ASP.NET Dynamic Data (which uses ASP.NET Web Forms).

Summary

Hopefully the above post provides a quick update on some of the new features and changes exposed with this week’s ASP.NET MVC source update drop. 

You can download it here if you want to start using it immediately.  Alternatively, you can wait a few weeks for the official ASP.NET MVC Preview 3 drop - which will have some more features (and incorporate feedback people provide on this week’s drop), deliver a more seamless installer, provide nice VS integration, and deliver up to date documentation.

For any questions/issues with this week’s drop of ASP.NET MVC, make sure to also check out the ASP.NET MVC forum on www.asp.net.

Hope this helps,

Scott

ASP.NET

• More ASP.NET Security Tutorials: The last three of Scott Mitchell’s excellent ASP.NET security tutorials.  His final three articles cover how to select user accounts, recover and change passwords, and unlock and approve user accounts.

• Building a VS 2008 Styled Grid with the ListView and DataPager Controls: Matt Berseth has a great article that talks about techniques you can use with the new ASP.NET 3.5 ListView control to create a nicely styled Grid UI - while preserving total control over the HTML and CSS used.  Also read his follow-up post here that talks about how to achieve the same UI with the GridView control.

• 50 Useful CSS Tips and Tricks: A useful page that provides a nice listing of various CSS tips, tricks and tools you can use for common web scenarios.

• Using a DataPager with the GridView Control - Implementing IPageableItemContainer: Matt Berseth has a cool article that shows how to use the new IPageableItemContainer interface to implement paging support with the new ASP.NET 3.5 DataPager control.

ASP.NET AJAX

• Accessible UpdatePanel: Bertrand Le Roy from the ASP.NET team has an article that describes how to make the ASP.NET AJAX’s UpdatePanel control accessible for screen-readers.

• ASP.NET AJAX Meets Virtual Earth: Alessandro Gallo, author of the excellent ASP.NET AJAX in Action book, has a nice series of articles that talks about using ASP.NET AJAX with Virtual Earth to implement mapping on your site.

• Faster Page Loading by Moving ASP.NET AJAX Scripts after visible content: Omar Al Zabir (the co-founder of www.PageFlakes.com) has a great article that describes a nice technique you can use to improve the perceived loading performance of an ASP.NET AJAX page.  I also highly recommend reading Omar’s great Building a Web 2.0 Portal with ASP.NET 3.5 book to learn some of his other suggestions and techniques.

• 3 Tips for Working with ASP.NET AJAX’s TabContainer Control: Matt Berseth continues his great articles on ASP.NET AJAX with some tips on working with the TabContainer control in the ASP.NET AJAX Control Toolkit.

• Building ASP.NET AJAX Components: Mike Ormond has written an excellent 8-part series that covers building re-usable ASP.NET AJAX components that work on both the client and server.

ASP.NET MVC

• An Introduction to ASP.NET MVC using VB: Bill Burrows from www.MyVBprof.com has put together a great set of online videos that introduce ASP.NET MVC using Visual Basic.  Also make sure to check out his video series on LINQ to XML using VB and LINQ to SQL using VB.

• ASP.NET MVC: Membership Starter Kit: Troy Goode has a built an awesome membership starter kit for ASP.NET MVC that provides registration and login pages for users to authenticate on your site, as well as a set of administration functionality that allows admins to create/manage users and roles.  Download it here.

• ASP.NET MVC: Action Filter for Handling Errors: Troy Goode has another good post that provides some ASP.NET MVC action filters for catching and handling runtime errors.

• How to Enable Pretty URLs with ASP.NET MVC and IIS6: James Geurts posts a useful article that describes how to enable extension-less URLs with ASP.NET MVC on IIS6 (note: you do not need to configure anything special with ASP.NET MVC on IIS7 to enable extension-less URL support).

Visual Studio

• PowerCommands for Visual Studio 2008: A free set of useful extensions for VS 2008 that add a bunch of cool features to the IDE.

• Coding Productivity: Macros, Shortcuts and Snippets: Kirill Osenkov has a nice blog post that shows of how to use Visual Studio’s macro feature to custom record useful time-savers.

Silverlight

• Dave Campbell’s Excellent Silverlight Link Series: Dave Campbell posts a regular series of links to new Silverlight articles and content on the web.  I highly recommend subscribing to his blog if you want to stay current with all the latest Silverlight articles and posts.

• Silverlight 2 Map / DataGrid Tutorial: Jason Zander has a great two-part Silverlight tutorial that demonstrates how to build a nice data-driven application that integrates a map control with a datagrid to filter and analyze data.

• CRUD operations with Silverlight 2, WCF and LINQ to SQL: Ronnie Saurenmann from the Swiss MSDN team has a nice video that shows off some basics of how to support inserts, updates and deletes using Silverlight 2 connected via WCF to a LINQ to SQL backend.

• Writing a Templated Silverlight 2 Control: Shawn Burke has a great tutorial post that walksthrough how to build a templated Silverlight control that implements an expand/collapse control.

Hope this helps,

Scott

The ASP.NET Dynamic Data support within that preview provided a first look at a cool new feature that enables you to quickly build data driven web-sites that work against a LINQ to SQL or LINQ to Entities object model.  ASP.NET Dynamic Data allows you to automatically render fully functional data entry and reporting pages that are dynamically constructed from your ORM data model meta-data.  In addition to supporting a dynamic rendering mode, it also allows you to optionally override and customize any of the view templates using any HTML or code you want (given you full control of the experience).

ASP.NET Dynamic Data Preview

Today we released an updated ASP.NET Dynamic Data Preview.  You can learn more about it and download it here.

This new dynamic data preview now works with the standard built-in ASP.NET data controls (GridView, ListView, FormView, DetailsView, etc).  The dynamic data support enables these controls to automatically handle foreign-key relationships.  For example, on a gridview you’ll now get automatic friendly name display of foreign key column values and automatic drop-down list selection support of these values when in edit mode:

The new dynamic data support also provides automatic UI validation support (both client-side and server-side) based on the constraints you set on your data model classes.  For example, if a column in the database is limited to 50 characters in size, and is marked as non-nullable, appropriate UI control validators will automatically be applied by ASP.NET dynamic data to enforce this constraint in the UI pages as well.  If you change the constraints within your LINQ to SQL or LINQ to Entities data model classes, the UI will automatically pick up these changes and enforce the new constraints on the next web request.

In addition to standard data model metadata, you can also declare custom metadata to further control validation and the default display of UI of objects. 

You will be able to use all of the above features with both LINQ to SQL and LINQ to Entities.

Visual Studio Dynamic Data Project Wizard

In addition to the core ASP.NET dynamic data runtime support, the VS web tools team today also shipped a first preview of a new dynamic data project wizard that enables you to quickly get a data driven web-site started.  The wizard allows you to select a database, and then the tables, views and sprocs within it that you want to build a LINQ to SQL data model around:

After creating a data model, the wizard allows you to easily choose dynamic data driven template pages to build UI around it:

You can then choose what type of inserting/editing/updating UI is supported on each page:

And when you click finish it will setup a project with your data model classes and data UI pages setup to run.  You can learn more about the wizard and watch it in action in a blog post and screencast here.

How to Get Started

You can learn more about this new dynamic data preview and download and run it locally here.

You can watch David Ebbo’s dynamic data presentation at MIX 08 to learn more about how it works.  Also check out Scott Hunter’s screen-cast here, and Brad Millington’s screen cast here.  David also has a post here that talks about the changes made between the December preview and today’s preview release.

You can ask questions and submit feedback via the www.asp.net forums here.

Hope this helps,

Scott

You can implement new custom controls by deriving a class from one of the existing Control classes (either a Control base class or from a control like TextBox, Button, etc).  Alternatively you can create re-usable User Controls - which make it easy to use a XAML markup file to compose a control’s UI (and which makes them super easy to build).

In Part 6 of my Digg.com tutorial blog series I showed how to create a new user control using VS 2008’s "Add New Item" project item dialog and by then defining UI within it.  This approach works great when you know up front that you want to encapsulate UI in a user control.  You can also use the same technique with Expression Blend.

Taking Existing UI and Encapsulating it as a User Control

Sometimes you don’t always know you want to encapsulate some UI functionality as a re-usable user control until after you’ve already started defining it on a parent page or control.

For example, we might be working on a form where we want to enable a user to enter shipping and billing information.  We might begin by creating some UI to encapsulate the address information.  To-do this we could add a <border> control to the page, nest a grid layout panel inside it (with 2 columns and 4 rows), and then place labels and textbox controls within it:

After carefully laying it all out, we might realize "hey - we are going to use the exact same UI for the billing address as well, maybe we should create a re-usable address user control so that we can avoid repeating ourselves". 

We could use the "add new item" project template approach to create a blank new user control and then copy/paste the above UI contents into it. 

An even faster trick that we can use within Blend, though, is to just select the controls we want to encapsulate as a user control in the designer, and then "right click" and choose the "Make Control" menu option:

When we select the "Make Control" menu item, Blend will prompt us for the name of a new user control to create:

We’ll name it "AddressUserControl" and hit ok. This will cause Blend to create a new user control that contains the content we selected:

When we do a re-build of the project and go back to the original page, we’ll see the same UI as before - except that the address UI is now encapsulated inside the AddressUserControl:

We could name this first AddressUserControl "ShippingAddress" and then add a second instance of the user control to the page to record the billing address (we’ll name this second control instance "BillingAddress"):

And now if we want to change the look of our addresses, we can do it in a single place and have it apply for both the shipping and billing information.

Data Binding Address Objects to our AddressUserControl

Now that we have some user controls that encapsulate our Address UI, let’s create an Address data model class that we can use to bind them against.  We’ll define the class like below (taking advantage of the new automatic properties language feature):

Within the code-behind file of our Page.xaml file we can then instantiate two instances of our Address object - one for the shipping address and one for the billing address (for the purposes of this sample we’ll populate them with dummy data).  We’ll then programmatically bind the Address objects to our AddressUserControls on the page.  We’ll do that by setting the "DataContext" property on each user control to the appropriate shipping or billing address data model instance:

Our last step will be to declaratively add {Binding} statements within our AddressUserControl.xaml file that will setup two-way databinding relationships between the "Text" properties of the TextBox controls within the user control and the properties on the Address data model object that we attached to the user control:

When we press F5 to run the application we’ll now get automatic data-binding of the Address data model objects with our AddressUserControls:

Because we setup the {Binding} declarations to be "Mode=TwoWay", changes users make in the textboxes will automatically get pushed back to the Address data model objects (no code required for this to happen). 

For example, we could change our original shipping address in the browser to instead go to Disneyland:

If we wire-up a debugger breakpoint on the "Click" event handler of the "Save" button (and then click the button), we can see how the above TextBox changes are automatically reflected in our "_shippingAddress" data model object:

We could then implement the SaveBtn_Click event handler to persist the Shipping and Billing Address data model objects however we want - without ever having to manually retrieve or manipulate anything in the UI controls on the page.

This clean view/model separation that WPF and Silverlight supports makes it easy to later change the UI of the address user controls without having to update any of our code in the page.  It also makes it possible to more easily unit test the functionality (read my last post to learn more about Silverlight Unit Testing).

Summary

WPF and Silverlight make it easy to encapsulate UI functionality within controls, and the user control mechanism they support provides a really easy way to take advantage of this.  Combining user controls with binding enables some nice view/model separation scenarios that allow you to write very clean code when working with data.

You can download a completed version of the above sample here if you want to run it on your own machine. 

To learn even more about Silverlight and WPF, check out my Silverlight Tutorials and Links Page.  I also highly recommend Karen Corby’s excellent MIX08 talk (which covers User Controls, Custom Controls, Styling, Control Templates and more), which you can watch online for free here.

Hope this helps,

Scott