ConfigurationPropertyAttribute Class

Definition

Namespace:

System.Configuration

Assembly:

System.Configuration.ConfigurationManager.dll

Declaratively instructs .NET to instantiate a configuration property. This class cannot be inherited.

public ref class ConfigurationPropertyAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Property)]
public sealed class ConfigurationPropertyAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Property)>]
type ConfigurationPropertyAttribute = class
    inherit Attribute

Public NotInheritable Class ConfigurationPropertyAttribute
Inherits Attribute

Inheritance

Object

Attribute

ConfigurationPropertyAttribute

Attributes

AttributeUsageAttribute

Examples

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.

using System;
using System.Configuration;

// Define a custom section.
// This class shows how to use the ConfigurationPropertyAttribute.
public class UrlsSection : ConfigurationSection
{
    [ConfigurationProperty("name", DefaultValue = "Contoso",
        IsRequired = true, IsKey = true)]
    public string Name
    {
        get
        {
            return (string)this["name"];
        }
        set
        {
            this["name"] = value;
        }
    }

    [ConfigurationProperty("url", DefaultValue = "http://www.contoso.com",
        IsRequired = true)]
    [RegexStringValidator(@"\w+:\/\/[\w.]+\S*")]
    public string Url
    {
        get
        {
            return (string)this["url"];
        }
        set
        {
            this["url"] = value;
        }
    }

    [ConfigurationProperty("port", DefaultValue = (int)0, IsRequired = false)]
    [IntegerValidator(MinValue = 0, MaxValue = 8080, ExcludeRange = false)]
    public int Port
    {
        get
        {
            return (int)this["port"];
        }
        set
        {
            this["port"] = value;
        }
    }
}

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

using System;
using System.Configuration;

public class UsingConfigurationPropertyAttribute
{

    // Create a custom section and save it in the 
    // application configuration file.
    static void CreateCustomSection()
    {
        try
        {

            // Create a custom configuration section.
            UrlsSection customSection = new UrlsSection();

            // Get the current configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None);

            // Add the custom section to the application
            // configuration file.
            if (config.Sections["CustomSection"] == null)
            {
                config.Sections.Add("CustomSection", customSection);
            }

            // 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 (ConfigurationErrorsException err)
        {
            Console.WriteLine("CreateCustomSection: {0}", err.ToString());
        }
    }

    static void ReadCustomSection()
    {
        try
        {
            // Get the application configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None) as Configuration;

            // Read and display the custom section.
            UrlsSection customSection =
                config.GetSection("CustomSection") as 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 (ConfigurationErrorsException err)
        {
            Console.WriteLine("ReadCustomSection(string): {0}", err.ToString());
        }
    }
    
    static void Main(string[] args)
    {
       
        // Get the name of the application.
        string appName =
            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();
    }
}

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>  

Remarks

You use the ConfigurationPropertyAttribute to decorate a configuration property, which will instruct .NET to instantiate and to initialize the property using the value of the decorating parameter.

Note

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, .NET 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 configuration system provides attribute types that you can use during the creation of custom configuration elements. There are two kinds of attribute types:

1. The types instructing .NET how to instantiate the custom configuration-element properties. These types include:

   • ConfigurationCollectionAttribute

   • ConfigurationPropertyAttribute

2. The types instructing .NET how to validate the custom configuration-element properties. These types include:

   • IntegerValidatorAttribute

   • LongValidatorAttribute

   • RegexStringValidatorAttribute

   • StringValidatorAttribute

   • TimeSpanValidatorAttribute

Constructors

ConfigurationPropertyAttribute(String)

Initializes a new instance of ConfigurationPropertyAttribute class.

Properties

DefaultValue	Gets or sets the default value for the decorated property.
IsDefaultCollection	Gets or sets a value indicating whether this is the default property collection for the decorated configuration property.
IsKey	Gets or sets a value indicating whether this is a key property for the decorated element property.
IsRequired	Gets or sets a value indicating whether the decorated element property is required.
Name	Gets the name of the decorated configuration-element property.
Options	Gets or sets the ConfigurationPropertyOptions for the decorated configuration-element property.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• ConfigurationProperty
• ConfigurationCollectionAttribute
• IntegerValidatorAttribute
• LongValidatorAttribute
• RegexStringValidatorAttribute
• StringValidatorAttribute
• TimeSpanValidatorAttribute