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ExpressionBuilderCollection Class

Represents a collection of ExpressionBuilder objects. This class cannot be inherited.

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

'Declaration
<ConfigurationCollectionAttribute(GetType(ExpressionBuilder))> _
Public NotInheritable Class ExpressionBuilderCollection _
	Inherits ConfigurationElementCollection
'Usage
Dim instance As ExpressionBuilderCollection

The ExpressionBuilderCollection class does not refer to any actual element in the underlying configuration file. It is a construct that allows easy access to the compilation information it contains.

This section provides two code examples. The first demonstrates how to declaratively specify values for several properties of the ExpressionBuilderCollection class. The second demonstrates how to use members of the ExpressionBuilderCollection class.

The following configuration file example shows how to declaratively specify values for several properties of the ExpressionBuilderCollection class.

<system.web>
  <compilation> 
    <expressionBuilders>
      <add 
        expressionPrefix="Resources" 
        type="System.Web.Compilation.ResourceExpressionBuilder"/>
      <add 
        expressionPrefix="ConnectionStrings" 
        type="System.Web.Compilation.
        ConnectionStringsExpressionBuilder"/>
      <add expressionPrefix="AppSettings" 
        type="System.Web.Compilation.AppSettingsExpressionBuilder" />
    </expressionBuilders>
  </compilation>
</system.web>

The following code example demonstrates how to use members of the ExpressionBuilderCollection class.

Imports System
Imports System.Configuration
Imports System.Web.Configuration

Namespace Samples.Aspnet.SystemWebConfiguration
  Class UsingExpressionBuildCollection
    Public Shared Sub Main()
      Try 
        ' Set the path of the config file. 
        Dim configPath As String = "" 

        ' Get the Web application configuration object. 
        Dim config As System.Configuration.Configuration = _
         WebConfigurationManager.OpenWebConfiguration(configPath)

        ' Get the section related object. 
        Dim configSection As System.Web.Configuration.CompilationSection = _
         CType(config.GetSection("system.web/compilation"), _
         System.Web.Configuration.CompilationSection)

        ' Display title and info.
        Console.WriteLine("ASP.NET Configuration Info")
        Console.WriteLine()

        ' Display Config details.
        Console.WriteLine("File Path: {0}", _
         config.FilePath)
        Console.WriteLine("Section Path: {0}", _
         configSection.SectionInformation.Name)

        ' Create a new ExpressionBuilder reference. 
        Dim myExpressionBuilder As ExpressionBuilder = _
          New ExpressionBuilder("myCustomExpression", "MyCustomExpressionBuilder")
        ' Add an ExpressionBuilder to the configuration.
        configSection.ExpressionBuilders.Add(myExpressionBuilder)

        ' Add an ExpressionBuilder to the configuration. 
        Dim myExpressionBuilder2 As ExpressionBuilder = _
         New ExpressionBuilder("myCustomExpression2", "MyCustomExpressionBuilder2")
        configSection.ExpressionBuilders.Add(myExpressionBuilder2)

        ' Display the ExpressionBuilder count.
        Console.WriteLine("ExpressionBuilder Count: {0}", _
          configSection.ExpressionBuilders.Count)

        ' Display the ExpressionBuildersCollection details. 
        Dim i = 1
        Dim j = 1
        For Each expressionBuilder As ExpressionBuilder In configSection.ExpressionBuilders()
          Console.WriteLine()
          Console.WriteLine("ExpressionBuilder {0} Details:", i)
          Console.WriteLine("Type: {0}", expressionBuilder.ElementInformation.Type)
          Console.WriteLine("Source: {0}", expressionBuilder.ElementInformation.Source)
          Console.WriteLine("LineNumber: {0}", expressionBuilder.ElementInformation.LineNumber)
          Console.WriteLine("Properties Count: {0}", expressionBuilder.ElementInformation.Properties.Count)
          j = 1
          For Each propertyItem As PropertyInformation In expressionBuilder.ElementInformation.Properties
            Console.WriteLine("Property {0} Name: {1}", j, propertyItem.Name)
            Console.WriteLine("Property {0} Value: {1}", j, propertyItem.Value)
            j = j + 1
          Next
          i = i + 1
        Next 

        ' Remove an ExpressionBuilder.
        configSection.ExpressionBuilders.RemoveAt _
         (configSection.ExpressionBuilders.Count - 1)

        ' Remove an ExpressionBuilder.
        configSection.ExpressionBuilders.Remove("myCustomExpression")

        ' Update if not locked. 
        If Not configSection.SectionInformation.IsLocked Then
          config.Save()
          Console.WriteLine("** Configuration updated.")
        Else
          Console.WriteLine("** Could not update, section is locked.")
        End If 

      Catch e As Exception
        ' Unknown error.
        Console.WriteLine(e.ToString())
      End Try 

      ' Display and wait
      Console.ReadLine()
    End Sub 
  End Class 
End Namespace

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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
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