ASP.NET MVC 1.0 Release Candidate Now Available
page 12 of 20
by Scott Guthrie
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Form Post Improvements

The RC build includes a number of form-post specific enhancements:

[Bind(Prefix=””)] No Longer Required for Common Scenarios

The RC build no longer requires you to explicitly use a [Bind] attribute (or set its prefix value to “”) in order to map incoming form post parameters that do not have a prefix to complex action method parameters.

To see what this means, let’s implement the “Create” scenario for our ProductsController.  We’ll begin by implementing the HTTP-GET version of our “Create” action method.  We’ll do this with code below that returns a View based on an empty Product object:

Figure 28

We can then right-click within our action method, choose the “Add View” command and scaffold a “create” view template that is based on a Product:

Figure 29

Notice above how our Html.TextBox() helper methods are referencing the “ProductName” and “SupplierID” properties on our Product object.  This will generate HTML markup like below where the input “name” attributes are “ProductName” and “SupplierID”:

Figure 30

We can then implement the HTTP-POST version of our “Create” action method. We’ll have our action method take a Product object as a method parameter:

Figure 31

With the ASP.NET MVC Beta we would have had to add a [Bind(Prefix=””)] attribute in front of our Product argument above – otherwise the ASP.NET MVC binding infrastructure would have only looked for form post values with a “productToCreate.” prefix (for example: productToCreate.ProductName and productToCreate.SupplierID) and not found the submitted values from our form (which don’t have a prefix). 

With the RC build, the default action method binders still first attempt to map a productToCreate.ProductName form value to the Product object.  If they don’t find such a value, though, they now also attempt to map “ProductName” to the Product object.  This makes scenarios where you pass in complex objects to an action method syntactically cleaner and less verbose.  You can take advantage of this feature both when mapping domain objects (like our Product object above) as well as with Presentation Model/ViewModel classes (like a ProductViewModel class).

A completed implementation of our Create action method (including basic input type error handling) might look like below:

Figure 32

Now our create action will save the Product object if all values are entered correctly.  When a user attempts to create a Product with invalid Product property values (for example: a string “Bogus” instead of a valid Decimal value), the form will redisplay and flag the invalid input elements in red:

Figure 33


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User Comments

Title: Awesome article, great work!   
Name: George Loew
Date: 2009-03-25 12:20:05 AM
Comment:
excellent article, scott! It is very useful and contain excellent information about ASP.NET MVC framework. I have had a chance to try this ASP.NET MVC technology with my current host (asphostcentral.com) and everything works beautifully.

I am rating 5 stars for this article and I am looking forward to your next articles.
Title: Cache Photo   
Name: Meysam
Date: 2009-03-05 2:14:50 AM
Comment:
Hi,
Is it possible to send cache status (304) in response to subsequent requests for a photo?

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