Discovering ASP.NET 4.5 Web Forms Jurgen

PostelmansU2U

Session Contents• Strongly Typed Data Data Controls• Model Binding – Retrieving Data• Model Binding – Value Providers• Model Binding – Updating Data• Model Binding - Validation

Strongly Typed Data Controls• Pre ASP.NET 4.5 Data Controls• Late-bound Eval/Bind functions • no compile time checking • Missing IntelliSense• No Navigation support (like Go To Definition)

Strongly Typed Data Controls• ASP.NET 4.5 introduces ModelType property on Data

Controls• Declare what type of data a control is bound to.• Strongly-typed Item and BoundItem property• Adds IntelliSense, compile-time checking and Navigation

support

Model Binding – Overview• Extends data binding to work with code-focused

data access• Uses concepts from ObjectDataSource and model

binding in ASP.NET MVC

Model Binding – Selecting Data• Set the control’s SelectMethod property to the name

of a method in your code• Should return a IEnumerable or IQueryable object

Model Binding – Selecting Data• Control calls the method at the appropriate time in

the page life cycle • Automatically binds the returned data. • No need to explicitly call the DataBind method

• Automatically supports paging and sorting• Handled by SQL Server

Model Binding – Filtering Data• Define the filtering parameters on the Select Method

in your code• Parameters get their value injected from Value

Providers• QueryString, Cookies, Form Values, Session ...• Custom Value Providers

Custom Value Providers• Implement IValueProvider interface in class• GetValue method should return the value to be assigned

to the parameter

Hooking up Custom Value Provider• Implement custom attribute inheriting from

ValueProviderSourceAttribute• Override GetValueProvider method and return an instance

of your custom Value Provider

Model Binding – Updating Data• Data Controls provide the following properties• UpdateMethod• InsertMethod• DeleteMethod

Model Binding – Updating Data• Approach 1• Define a first parameter of the type the control is bound to. • Model binding implicitly creates an instance of this type • Model Binding attempts to bind the values from the data control based on

expressions you write in the template• Only works for simple cases • What if you only display a subset of the fields ? Relationships ?

Model Binding – Updating Data

• Approach 2• First load the load the object to be updated from database• Define the update method with a first parameter representing the Primary Key

field • Ask Model Binding system to bind data-control values onto the

members • TryUpdateModel method

Model Binding - Validation• Model Binding supports Data Annotations from

System.ComponentModel.DataAnnotations namespace

Model Binding - Validation• When control values are model bound on the Type

these validation rules are checked• Page object now has a ModelState property• Can be used to iterate over validation errors• ModelState.IsValid returns true if there where any Model Binding

errors

Displaying Model Validation Errors• ValidationSummary control has new

ShowModelStateErrors property• ValidationSummuray will access the ModelState and

display any validation errors in contains

Extending the Validation• Implement a custom attribute inheriting from

ValidationAttribute base class• Override IsValid method and implement you custom

validation logic.

Q&A

© 2012 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.