How To Create Custom Configuration Sections Using ConfigurationSection?

The ConfigurationSection class is the base class for all the new configuration sections. This class inherits from ConfigurationElement and provides for either a declarative programming style using property attributes to control the section structure or a strictly programmable model for complete control over the section structure.

You can extend ASP.NET configuration settings with XML configuration elements of your own. To do this, you create a custom configuration section handler. The handler must be a .NET Framework class that inherits from the ConfigurationSection class. The section handler interprets and processes the settings that are defined in XML configuration elements in a specific section of a Web.config file. You can read and write these settings through the handler's properties.

Your custom section handlers can be implemented by using one of two implementation models: the programmatic model or the declarative model.

Declarative Implementation Model

This model, which is also called the attributed model, allows you to define a section attribute by using a property and setting attributes. These attributes instruct the ASP.NET configuration system about the property types and their default values. With this information, which is obtained through reflection, the ASP.NET configuration system creates the section property objects and performs the required initialization.

The following example shows how to create a handler for a custom configuration section named "PageAppearance." The section has a RemoteOnly attribute and Font and Color elements. The code shows how to use string, integer, and Boolean attributes. It also shows how to use string and integer validators for those attributes. (The Boolean attribute is automatically validated.) The validators check the format of the configuration markup at run time and throw exceptions if the values provided for the custom attributes do not meet the specified criteria.

using System;
using System.Collections;
using System.Text;
using System.Configuration;
using System.Xml;

namespace Samples.AspNet
{
    public class PageAppearanceSection : ConfigurationSection
    {
        // Create a "remoteOnly" attribute.
        [ConfigurationProperty("remoteOnly", DefaultValue = "false", IsRequired = false)]
        public Boolean RemoteOnly
        {
            get
            {
                return (Boolean)this["remoteOnly"];
            }
            set
            {
                this["remoteOnly"] = value;
            }
        }

        // Create a "font" element.
        [ConfigurationProperty("font")]
        public FontElement Font
        {
            get
            {
                return (FontElement)this["font"]; }
            set
            { this["font"] = value; }
        }

        // Create a "color element."
        [ConfigurationProperty("color")]
        public ColorElement Color
        {
            get
            {
                return (ColorElement)this["color"];
            }
            set
            { this["color"] = value; }
        }
    }

    // Define the "font" element
    // with "name" and "size" attributes.
    public class FontElement : ConfigurationElement
    {
        [ConfigurationProperty("name", DefaultValue="Arial", IsRequired = true)]
        [StringValidator(InvalidCharacters = "~!@#$%^&*()[]{}/;'\"|\\", MinLength = 1, MaxLength = 60)]
        public String Name
        {
            get
            {
                return (String)this["name"];
            }
            set
            {
                this["name"] = value;
            }
        }

        [ConfigurationProperty("size", DefaultValue = "12", IsRequired = false)]
        [IntegerValidator(ExcludeRange = false, MaxValue = 24, MinValue = 6)]
        public int Size
        {
            get
            { return (int)this["size"]; }
            set
            { this["size"] = value; }
        }
    }

    // Define the "color" element
    // with "background" and "foreground" attributes.
    public class ColorElement : ConfigurationElement
    {
        [ConfigurationProperty("background", DefaultValue = "FFFFFF", IsRequired = true)]
        [StringValidator(InvalidCharacters = "~!@#$%^&*()[]{}/;'\"|\\GHIJKLMNOPQRSTUVWXYZ", MinLength = 6, MaxLength = 6)]
        public String Background
        {
            get
            {
                return (String)this["background"];
            }
            set
            {
                this["background"] = value;
            }
        }

        [ConfigurationProperty("foreground", DefaultValue = "000000", IsRequired = true)]
        [StringValidator(InvalidCharacters = "~!@#$%^&*()[]{}/;'\"|\\GHIJKLMNOPQRSTUVWXYZ", MinLength = 6, MaxLength = 6)]
        public String Foreground
        {
            get
            {
                return (String)this["foreground"];
            }
            set
            {
                this["foreground"] = value;
            }
        }

    }

}

The configuration file is shown as below:

<configuration>

<!-- Configuration section-handler declaration area. -->

  <!-- Configuration section settings area. -->
  <pageAppearanceGroup>
    <pageAppearance remoteOnly="true">
      <font name="TimesNewRoman" size="18"/>
      <color background="000000" foreground="FFFFFF"/>
    </pageAppearance>
  </pageAppearanceGroup>

  <!-- Other configuration settings, such as system.web -->

</configuration>