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appSettings Element (General Settings Schema)

Contains custom application settings, such as file paths, XML Web service URLs, or any information that is stored in the.ini file for an application.

configuration Element (General Settings Schema)
  appSettings Element (General Settings Schema)
   file="relative file name" >

The following sections describe attributes, child elements, and parent elements.





Optional String attribute.

Specifies a relative path to an external file that contains custom application configuration settings. The specified file contains the same kind of settings that are specified in the appSettings add, clear, and remove attributes and uses the same key/value pair format as those elements.

The path that is specified is relative to the local configuration file. The runtime ignores the attribute, if the specified file cannot be found.

Because any changes to the Web.config file cause the application to restart, using a separate file allows users to modify values that are in the appSettings section without causing the application to restart. The contents of the separate file are merged with the appSettings section in the Web.config file. This functionality is limited to the appSettings attribute.

Note   In the .NET Framework version 2.0, you can now include configuration settings in a separate file for all configuration elements that support the configSource attribute. However, when you use the configSource attribute, you must move the entire section to the separate file because there is no merging of element settings. There is a one-time write to the Web.config file when using the configSource attribute. This causes the application to restart, but subsequent updates to the section are written directly to the separate file and do not cause subsequent application restarts. For more information, see ConfigSource.

Inherited attributes

Optional attributes.

Attributes inherited by all section elements.

Child Elements




Optional element.

Adds a custom application setting as a name/value pair to the application settings collection.


Optional element.

Removes all references to inherited custom application settings and allows only the references that are added by the current add attribute.


Optional element.

Removes a reference to an inherited custom application setting from the application settings collection.

Parent Elements




Specifies the required root element in every configuration file that is used by the common language runtime and the .NET Framework applications.


Specifies the root element for the ASP.NET configuration settings in a configuration file and contains configuration elements that configure ASP.NET Web applications and control how the applications behave.

The appSettings element stores custom application configuration information, such as file paths, XML Web service URLs, or any information that is stored in the.ini file for an application. The key/value pairs that are specified in the appSettings element can be accessed in code using the ConfigurationManager class. Refer to the code example shown in the class to see how to access the appSettings programmatically.

You can use the file attribute to specify a configuration file that provides additional settings or overrides the settings that are specified in the appSettings element. You can use the file attribute in source control team development scenarios, such as when a user wants to override the project settings that are specified in an application configuration file. Configuration files that are specified in a file attribute must have the appSettings element rather than configuration element as the root node.

In the .NET Framework version 2.0 applications, store database connection strings in the connectionStrings Element (ASP.NET Settings Schema) collection instead of the application settings collection.

Default Configuration

The following default appSettings element is not explicitly configured in the Machine.config file or in the root Web.config file. However, it is the default configuration that is returned by application.

   <appSettings file="">
         <clear />

Configuration files that are specified in a file attribute must have the appSettings element rather than the configuration element as the root node.

The following code example demonstrates how to use the correct form for a configuration file that is specified in the file attribute.

<?xml version="1.0" encoding="utf-8" ?>
<add key="Application1" value="MyApplication1" />
<add key="Setting1" value="MySetting" />

The following code example shows how to define a custom application setting in a configuration file.

        <add key="Application Name" value="MyApplication" />

Configuration section handler


Configuration member




Configurable locations


Root-level Web.config

Application-level Web.config

Virtual or physical directory–level Web.config


Microsoft Internet Information Services (IIS) 5.0, 5.1, or 6.0

The .NET Framework version 1.0, 1.1, or 2.0

Microsoft Visual Studio 2003 or Visual Studio 2005