Property Method (Expression, String)

Expression.Property Method (Expression, String)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Creates a MemberExpression that represents accessing a property.

Namespace:  System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)

'Declaration
Public Shared Function Property ( _
	expression As Expression, _
	propertyName As String _
) As MemberExpression

Parameters

expression
Type: System.Linq.Expressions.Expression
An Expression whose Type contains a property named propertyName. This can be Nothing for static properties.
propertyName
Type: System.String
The name of a property to be accessed.

Return Value

Type: System.Linq.Expressions.MemberExpression
A MemberExpression that has the NodeType property equal to MemberAccess, the Expression property set to expression, and the Member property set to the PropertyInfo that represents the property denoted by propertyName.

ExceptionCondition
ArgumentNullException

expression or propertyName is Nothing.

ArgumentException

No property named propertyName is defined in expression.Type or its base types.

The Type property of the resulting MemberExpression is equal to the PropertyType property of the PropertyInfo that represents the property denoted by propertyName.

This method searches expression.Type and its base types for a property that has the name propertyName. Public properties are given preference over non-public properties. If a matching property is found, this method passes expression and the PropertyInfo that represents that property to Property.

The following example shows how to create an expression that represents accessing a property.


' Add the following directive to your file:
' Imports System.Linq.Expressions  

Class TestPropertyClass
    Public Property Sample As Integer
End Class

Sub TestProperty()

    Dim obj As New TestPropertyClass()
    obj.Sample = 40

    ' This expression represents accessing a property.
    ' For static properties, the first parameter must be Nothing.
    Dim propertyExpr As Expression = Expression.Property(
          Expression.Constant(obj),
          "sample"
      )

    ' The following statement first creates an expression tree,
    ' then compiles it, and then runs it.
    outputBlock.Text &= Expression.Lambda(Of Func(Of Integer))(propertyExpr).Compile()() & vbCrLf
End Sub

' This code example produces the following output:
'
' 40


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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