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.NET Framework 3.5
 GetCodeExpression Method
This page is specific to
Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:
.NET Framework Class Library
ExpressionBuilder..::.GetCodeExpression Method

Updated: November 2007

When overridden in a derived class, returns code that is used during page execution to obtain the evaluated expression.

Namespace:  System.Web.Compilation
Assembly:  System.Web (in System.Web.dll)

Visual Basic (Declaration)
Public MustOverride Function GetCodeExpression ( _
    entry As BoundPropertyEntry, _
    parsedData As Object, _
    context As ExpressionBuilderContext _
) As CodeExpression
Visual Basic (Usage)
Dim instance As ExpressionBuilder
Dim entry As BoundPropertyEntry
Dim parsedData As Object
Dim context As ExpressionBuilderContext
Dim returnValue As CodeExpression

returnValue = instance.GetCodeExpression(entry, _
    parsedData, context)
C#
public abstract CodeExpression GetCodeExpression(
    BoundPropertyEntry entry,
    Object parsedData,
    ExpressionBuilderContext context
)
Visual C++
public:
virtual CodeExpression^ GetCodeExpression(
    BoundPropertyEntry^ entry, 
    Object^ parsedData, 
    ExpressionBuilderContext^ context
) abstract
J#
public abstract CodeExpression GetCodeExpression(
    BoundPropertyEntry entry,
    Object parsedData,
    ExpressionBuilderContext context
)
JScript
public abstract function GetCodeExpression(
    entry : BoundPropertyEntry, 
    parsedData : Object, 
    context : ExpressionBuilderContext
) : CodeExpression

Parameters

entry
Type: System.Web.UI..::.BoundPropertyEntry

The object that represents information about the property bound to by the expression.

parsedData
Type: System..::.Object

The object containing parsed data as returned by ParseExpression.

context
Type: System.Web.Compilation..::.ExpressionBuilderContext

Contextual information for the evaluation of the expression.

Return Value

Type: System.CodeDom..::.CodeExpression

A CodeExpression that is used for property assignment.

Classes that inherit from the ExpressionBuilder class must implement the GetCodeExpression abstract method.

Notes to Inheritors:

If you implement a custom expression builder, you must perform the proper type casting for the control property and return the cast operation in the CodeExpression object.

The following code example demonstrates how to return a CodeExpression object by overriding the GetCodeExpression method.

Visual Basic
Public Overrides Function GetCodeExpression(ByVal entry _
   As BoundPropertyEntry, ByVal parsedData As Object, ByVal context _
   As ExpressionBuilderContext) As CodeExpression
    Dim type1 As Type = entry.DeclaringType
    Dim descriptor1 As PropertyDescriptor = _
       TypeDescriptor.GetProperties(type1)(entry.PropertyInfo.Name)
    Dim expressionArray1(2) As CodeExpression
    expressionArray1(0) = New CodePrimitiveExpression(entry.Expression.Trim())
    expressionArray1(1) = New CodeTypeOfExpression(type1)
    expressionArray1(2) = New CodePrimitiveExpression(entry.Name)
    Return New CodeCastExpression(descriptor1.PropertyType, _
       New CodeMethodInvokeExpression(New CodeTypeReferenceExpression _
       (MyBase.GetType()), "GetEvalData", expressionArray1))
End Function

C#
    public override CodeExpression GetCodeExpression(BoundPropertyEntry entry, 
    object parsedData, ExpressionBuilderContext context)
    {
        Type type1 = entry.DeclaringType;
        PropertyDescriptor descriptor1 = TypeDescriptor.GetProperties(type1)[entry.PropertyInfo.Name];
        CodeExpression[] expressionArray1 = new CodeExpression[3];
        expressionArray1[0] = new CodePrimitiveExpression(entry.Expression.Trim());
        expressionArray1[1] = new CodeTypeOfExpression(type1);
        expressionArray1[2] = new CodePrimitiveExpression(entry.Name);
        return new CodeCastExpression(descriptor1.PropertyType, new CodeMethodInvokeExpression(new 
       CodeTypeReferenceExpression(base.GetType()), "GetEvalData", expressionArray1));
    }

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, 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
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