ConfigurationPropertyAttribute Class
Declaratively instructs the .NET Framework to instantiate a configuration property. This class cannot be inherited.
Assembly: System.Configuration (in System.Configuration.dll)
You use the ConfigurationPropertyAttribute to decorate a configuration property, which will instruct the .NET Framework to instantiate and to initialize the property using the value of the decorating parameter.
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The simplest way to create a custom configuration element is to use the attributed (declarative) model. You declare the custom public properties and decorate them with the ConfigurationPropertyAttribute attribute. For each property marked with this attribute, the .NET Framework uses reflection to read the decorating parameters and create a related ConfigurationProperty instance. You can also use the programmatic model, in which case it is your responsibility to declare the custom public properties and return their collection. |
The .NET Framework configuration system provides attribute types that you can use during the creation of custom configuration elements. There are two kinds of attribute types:
The types instructing the .NET Framework how to instantiate the custom configuration-element properties. These types include:
ConfigurationPropertyAttribute
The types instructing the .NET Framework how to validate the custom configuration-element properties. These types include:
The following example shows how to define the properties of a custom ConfigurationSection object using the ConfigurationPropertyAttribute attribute.
The example contains two classes. The UrlsSection custom class uses the ConfigurationPropertyAttribute to define its own properties. The UsingConfigurationPropertyAttribute class uses the UrlsSection to read and write the custom section in the application configuration file.
Imports Microsoft.VisualBasic Imports System Imports System.Configuration ' Define a custom section. ' This class shows how to use the ConfigurationPropertyAttribute. Public Class UrlsSection Inherits ConfigurationSection <ConfigurationProperty("name", DefaultValue:="Contoso", IsRequired:=True, IsKey:=True)> Public Property Name() As String Get Return CStr(Me("name")) End Get Set(ByVal value As String) Me("name") = value End Set End Property <ConfigurationProperty("url", DefaultValue:="http://www.contoso.com", IsRequired:=True), RegexStringValidator("\w+:\/\/[\w.]+\S*")> Public Property Url() As String Get Return CStr(Me("url")) End Get Set(ByVal value As String) Me("url") = value End Set End Property <ConfigurationProperty("port", DefaultValue:=0, IsRequired:=False), IntegerValidator(MinValue:=0, MaxValue:=8080, ExcludeRange:=False)> Public Property Port() As Integer Get Return CInt(Fix(Me("port"))) End Get Set(ByVal value As Integer) Me("port") = value End Set End Property End Class
Imports System Imports System.Configuration Public Class UsingConfigurationPropertyAttribute ' Create a custom section and save it in the ' application configuration file. Private Shared Sub CreateCustomSection() Try ' Create a custom configuration section. Dim customSection As New UrlsSection() ' Get the current configuration file. Dim config As System.Configuration.Configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None) ' Add the custom section to the application ' configuration file. If config.Sections("CustomSection") Is Nothing Then config.Sections.Add("CustomSection", customSection) End If ' Save the application configuration file. customSection.SectionInformation.ForceSave = True config.Save(ConfigurationSaveMode.Modified) Console.WriteLine("Created custom section in the application configuration file: {0}", config.FilePath) Console.WriteLine() Catch err As ConfigurationErrorsException Console.WriteLine("CreateCustomSection: {0}", err.ToString()) End Try End Sub Private Shared Sub ReadCustomSection() Try ' Get the application configuration file. Dim config As System.Configuration.Configuration = TryCast(ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None), Configuration) ' Read and display the custom section. Dim customSection As UrlsSection = TryCast(config.GetSection("CustomSection"), UrlsSection) Console.WriteLine("Reading custom section from the configuration file.") Console.WriteLine("Section name: {0}", customSection.Name) Console.WriteLine("Url: {0}", customSection.Url) Console.WriteLine("Port: {0}", customSection.Port) Console.WriteLine() Catch err As ConfigurationErrorsException Console.WriteLine("ReadCustomSection(string): {0}", err.ToString()) End Try End Sub Shared Sub Main(ByVal args() As String) ' Get the name of the application. Dim appName As String = Environment.GetCommandLineArgs()(0) ' Create a custom section and save it in the ' application configuration file. CreateCustomSection() ' Read the custom section saved in the ' application configuration file. ReadCustomSection() Console.WriteLine("Press enter to exit.") Console.ReadLine() End Sub End Class
The following is an excerpt of the configuration file containing the custom section as defined in the previous sample.
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="CustomSection" type="UrlsSection, UsingConfigurationPropertyAttribute, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</configSections>
<CustomSection name="Contoso" url="http://www.contoso.com" />
</configuration>
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.
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