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ConfigurationPropertyAttribute Class

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

Namespace:  System.Configuration
Assembly:  System.Configuration (in System.Configuration.dll)
[AttributeUsageAttribute(AttributeTargets.Property)]
public sealed class ConfigurationPropertyAttribute : Attribute

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.

NoteNote:

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:

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

  2. 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.

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;
        }
    }
}
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();
    }
}

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>
System.Object
  System.Attribute
    System.Configuration.ConfigurationPropertyAttribute
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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