Evaluates data-binding expressions at run time.
(in System.Web.dll)
Visual Basic (Declaration)
Public Shared Function Eval ( _
container As Object, _
expression As String _
) As Object
Dim container As Object
Dim expression As String
Dim returnValue As Object
returnValue = DataBinder.Eval(container, _
expression)
public static Object Eval(
Object container,
string expression
)
public:
static Object^ Eval(
Object^ container,
String^ expression
)
public static function Eval(
container : Object,
expression : String
) : Object
Parameters
- container
- Type: System..::.Object
The object reference against which the expression is evaluated. This must be a valid object identifier in the page's specified language.
- expression
- Type: System..::.String
The navigation path from the container object to the public property value to be placed in the bound control property. This must be a string of property or field names separated by periods, such as Tables[0].DefaultView.[0].Price in C# or Tables(0).DefaultView.(0).Price in Visual Basic.
Return Value
Type:
System..::.ObjectAn Object instance that results from the evaluation of the data-binding expression.
| Exception | Condition |
|---|
| ArgumentNullException |
expression is nullNothingnullptra null reference (Nothing in Visual Basic) or is an empty string after trimming. |
The value of the expression parameter must evaluate to a public property.
This method is automatically called when you create data bindings in a rapid application development (RAD) designer such as Visual Studio. You can also use it declaratively to simplify casting to a text string. To do so, you use the <%# %> expression syntax, as used in standard ASP.NET data binding.
This method is particularly useful when binding data to controls that are in a templated list.
.gif) Note: |
|---|
Because this method performs late-bound evaluation, using reflection at run time, it can cause performance to noticeably slow compared to standard ASP.NET data-binding syntax. |
For any of the list Web controls, such as GridView, DetailsView, DataList, or Repeater, container should be Container.DataItem. If you are binding against the page, container should be Page.
The following code example demonstrates how you could use the Eval method declaratively to bind to a Price field. This example uses container syntax that assumes you are using one of the list Web controls.
<%# DataBinder.Eval(Container.DataItem, "Price") %>
<%# DataBinder.Eval (Container.DataItem, "Price") %>
<%# DataBinder.Eval (Container.DataItem, "Price") %>
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
Reference
Other Resources