Maarten Balliauw {blog}

ASP.NET, ASP.NET MVC, Windows Azure, PHP, ...

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Supporting multiple submit buttons on an ASP.NET MVC view

Multiple buttons on an ASP.NET MVC view A while ago, I was asked for advice on how to support multiple submit buttons in an ASP.NET MVC application, preferably without using any JavaScript. The idea was that a form could contain more than one submit button issuing a form post to a different controller action.

The above situation can be solved in many ways, one a bit cleaner than the other. For example, one could post the form back to one action method and determine which method should be called from that action method. Good solution, however: not standardized within a project and just not that maintainable… A better solution in this case was to create an ActionNameSelectorAttribute.

Whenever you decorate an action method in a controller with the ActionNameSelectorAttribute (or a subclass), ASP.NET MVC will use this attribute to determine which action method to call. For example, one of the ASP.NET MVC ActionNameSelectorAttribute subclasses is the ActionNameAttribute. Guess what the action name for the following code snippet will be for ASP.NET MVC:

[code:c#]

public class HomeController : Controller
{
    [ActionName("Index")]
    public ActionResult Abcdefghij()
    {
        return View();
    }
}

[/code]

That’s correct: this action method will be called Index instead of Abcdefghij. What happens at runtime is that ASP.NET MVC checks the ActionNameAttribute and asks if it applies for a specific request. Now let’s see if we can use this behavior for our multiple submit button scenario.

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The view

Since our view should not be aware of the server-side plumbing, we can simply create a view that looks like this.

[code:c#]

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<MvcMultiButton.Models.Person>" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Create person</title>
    <script src="<%=Url.Content("~/Scripts/MicrosoftAjax.js")%>" type="text/javascript"></script>
    <script src="<%=Url.Content("~/Scripts/MicrosoftMvcAjax.js")%>" type="text/javascript"></script>
</head>
<body>

    <% Html.EnableClientValidation(); %>
    <% using (Html.BeginForm()) {%>

        <fieldset>
            <legend>Create person</legend>
            <p>
                <%= Html.LabelFor(model => model.Name) %>
                <%= Html.TextBoxFor(model => model.Name) %>
                <%= Html.ValidationMessageFor(model => model.Name) %>
            </p>
            <p>
                <%= Html.LabelFor(model => model.Email) %>
                <%= Html.TextBoxFor(model => model.Email) %>
                <%= Html.ValidationMessageFor(model => model.Email) %>
            </p>
            <p>
                <input type="submit" value="Cancel" name="action" />
                <input type="submit" value="Create" name="action" />
            </p>
        </fieldset>

    <% } %>

    <div>
        <%=Html.ActionLink("Back to List", "Index") %>
    </div>

</body>
</html>

[/code]

Note the two submit buttons (namely “Cancel” and “Create”), both named “action” but with a different value attribute.

The controller

Our controller should also not contain too much logic for determining the correct action method to be called. Here’s what I propose:

[code:c#]

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View(new Person());
    }

    [HttpPost]
    [MultiButton(MatchFormKey="action", MatchFormValue="Cancel")]
    public ActionResult Cancel()
    {
        return Content("Cancel clicked");
    }

    [HttpPost]
    [MultiButton(MatchFormKey = "action", MatchFormValue = "Create")]
    public ActionResult Create(Person person)
    {
        return Content("Create clicked");
    }
}

[/code]

Some things to note:

  • There’s the Index action method which just renders the view described previously.
  • There’s a Cancel action method which will trigger when clicking the Cancel button.
  • There’s a Create action method which will trigger when clicking the Create button.

Now how do these last two work… You may also have noticed the MultiButtonAttribute being applied. We’ll see the implementation in a minute. In short, this is a subclass for the ActionNameSelectorAttribute, triggering on the parameters MatchFormKey and MatchFormValues. Now let’s see how the MultiButtonAttribute class is built…

The MultiButtonAttribute class

Now do be surprised of the amount of code that is coming…

[code:c#]

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class MultiButtonAttribute : ActionNameSelectorAttribute
{
    public string MatchFormKey { get; set; }
    public string MatchFormValue { get; set; }

    public override bool IsValidName(ControllerContext controllerContext, string actionName, MethodInfo methodInfo)
    {
        return controllerContext.HttpContext.Request[MatchFormKey] != null &&
            controllerContext.HttpContext.Request[MatchFormKey] == MatchFormValue;
    }
}

[/code]

When applying the MultiButtonAttribute to an action method, ASP.NET MVC will come and call the IsValidName method. Next, we just check if the MatchFormKey value is one of the request keys, and the MatchFormValue matches the value in the request. Simple, straightforward and re-usable.

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Book review: Zend Framework 1.8 Web Application Development

Zend Framework 1.8 Web Application Development My book shelf is starting to look a lot like the warehouse of Packt Publishing: I’ve received yet another book from them. Different from all previous reviews I did: this one is a PHP book, titled “Zend Framework 1.8 Web Application Development” by Keith Pope.

A chapter overview:

  • Chapter 1: Creating a Basic MVC Application
  • Chapter 2: The Zend Framework MVC Architecture
  • Chapter 3: Storefront Basic Setup
  • Chapter 4: Storefront Models (great chapter!)
  • Chapter 5: Implementing the Catalog
  • Chapter 6: Implementing User Accounts
  • Chapter 7: The Shopping Cart
  • Chapter 8: Authentication and Authorization
  • Chapter 9: The Administration Area
  • Chapter 10: Storefront Roundup
  • Chapter 11: Storefront Optimization
  • Chapter 12: Testing the Storefront

Let’s also state the obvious: Zend Framework evolves much faster than publishers. The framework is now at 1.9.6, while the book covers 1.8.0. Do not let this stop you from reading this book! Let me explain why…

  1. The book covers all concepts and components in the Zend Framework in a full-blown application that is built up from scratch.
  2. Next to that, Keith Pope focuses a lot on the application design, using interfaces, unit testing, mocking, dependency injection, … Want to learn a lot about good application design? Then this is the number one reason to read this book!

These 2 points actually summarize the whole book. Great read, great content and a must-read for everyone who is not completely sure about his application design skills. Congratulations, Keith!

MSDN - Converting an existing ASP.NET application to Windows Azure

Back from PDC 2009 with a lot of information on Windows Azure, I did an MSDN Live Meeting on ASP.NET and Windows Azure today. Here's the slide deck and demo code.

Abstract: "Put your stuff in the cloud! Windows Azure allows you to take advantage of cloud computing infranstructure for hosting, computing, and storage of your applications. In this demo filled session we take an existing ASP.Net Application and move it to be hosted in Windows Azure, while taking advantage of Windows Azure storage."

Example code can be downloaded here: MSDN - Converting an existing ASP.NET application to Windows Azure.zip (2.01 mb)

If you want more info about Windows Azure and how to develop, architect or benefit from the platform as a whole, register freely at the Azure User Group Belgium.

Before you get started, you need to have a Windows Azure token. Request a token by completing the application here. Tokens are generally issued within a few hours. Once you have received your token, redeem it at http://windows.azure.com. Afterwards, you can deploy your application using the interface at http://windows.azure.com or by issuing a right-click -> Publish... in your Visual Studio solution.

Windos Azure Developer Portal

Thank you for attending!

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Microsoft PDC09 day 2 keynote highlights

Happiness, pure happiness!

Day 2 keynote at Microsoft PDC 2009 was quite exciting. To sum things up: Silverlight 4 went beta, IE9 features were previewed, and we got an external hard disk, nicely fitted in a tablet-pc format case. How thoughtful!

Here’s some of the novelties:

Silverlight 4 Beta

This was a good starter… It’s really incredibly feature packed! In my opinion, I think WCF can now be called obsolete as well, but no announcements on that :-) Anyway, here’s a list of new features: webcam access, multicast streaming, offline DRM and output protection, printing, clipboard support, out-of-browser and out-of-sandbox support, drag and drop, implicit styling, a HTML control, rich-text editing, breathe, ability to share assemblies with .NET 4, data binding improvements, udp multicast, REST enhancements, TCP channel support, …

Also check Tim Heuer’s blog post over at http://timheuer.com/blog/archive/2009/11/18/whats-new-in-silverlight-4-complete-guide-new-features.aspx.

IE9

Yes, IE9 was announced. Running JavaScript lots faster, passing more of the ACID3 test (still not all), and the coolest part: Direct3D rendering of all graphic content. This was demoed and approved by the audience: everything is so muh faster and smoother!

WCF RIA Services

Check out Brad Abrams’ blog for this: http://blogs.msdn.com/brada/archive/2009/11/18/welcome-to-wcf-ria-services-beta.aspx

Basically a rename of RIA services, and converted to run on top of WCF rather than an own transport layer implementation in previous versions.

Overall: a great PDC09 day two!

Microsoft PDC09 keynote highlights

Finally found some time to write a short blog post on the announcements this morning at PDC 2009.Microsoft PDC keynote highlights Ray Ozzie started the keynote this morning, focusing on Microsoft’s “three-screen” vision for the future. There will be three screens connected to the cloud: TV, (handheld) devices and of course good old PC. This vision is driven by some key players: Windows 7, Internet Explorer, Silverlight and Windows Azure. Make sure to have a look at these four if you want to play in this future.

Some announcements were made as well:

Had a great day yesterday, driving trough the city of Los Angeles and looking at various places in town. Conference day one was also very interesting, lots of good sessions. Currently missing a session slot though, waiting for a Channel9 interview on the Windows Azure SDK for PHP. Stay tuned!

Localize ASP.NET MVC 2 DataAnnotations validation messages

Living in a country where there are there are three languages being used, almost every application you work on requires some form of localization. In an earlier blog post, I already mentioned ASP.NET MVC 2’s DataAnnotations support for doing model validation. Ever since, I was wondering if it would be possible to use resource files or something to do localization of error messages, since every example that could be found on the Internet looks something like this:

[code:c#]

[MetadataType(typeof(PersonBuddy))]
public class Person
{
    public string Name { get; set; }
    public string Email { get; set; }
}

public class PersonBuddy
{
    [Required(ErrorMessage = "Name is required.")]
    public string Name { get; set; }

    [Required(ErrorMessage = "E-mail is required.")
    public string Email { get; set; }
}

[/code]

Yes, those are hardcoded error messages. And yes, only in one language. Let’s see how localization of these would work.

1. Create a resource file

Add a resource file to your ASP.NET MVC 2 application. Not in App_GlobalResources or App_LocalResources, just a resource file in a regular namespace. Next, enter all error messages that should be localized in a key/value manner. Before you leave this file, make sure that the Access Modifier property is set to Public.

Access modifier in resource file

2. Update your “buddy classes”

Update your “buddy classes” (or metadata classes or whatever you call them) to use the ErrorMessageResourceType and ErrorMessageResourceName parameters instead of the ErrorMessage parameter that you normally pass. Here’s the example from above:

[code:c#]

[MetadataType(typeof(PersonBuddy))]
public class Person
{
    public string Name { get; set; }
    public string Email { get; set; }
}

public class PersonBuddy
{
    [Required(ErrorMessageResourceType = typeof(Resources.ModelValidation), ErrorMessageResourceName = "NameRequired")]
    public string Name { get; set; }

    [Required(ErrorMessageResourceType = typeof(Resources.ModelValidation), ErrorMessageResourceName = "EmailRequired")]
    public string Email { get; set; }
}

[/code]

3. See it work!

After creating a resource file and updating the buddy classes, you can go back to work and use model binders, ValidationMessage and ValidationSummary. ASP.NET will make sure that the correct language is used based on the thread culture info.

Localized error messages

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