Provides access to configuration files for client applications. This class cannot be inherited.
Assembly: System.Configuration (in System.Configuration.dll)
Thetype exposes the following members.
|GetSection||Retrieves a specified configuration section for the current application's default configuration.|
|OpenExeConfiguration(ConfigurationUserLevel)||Opens the configuration file for the current application as a Configuration object.|
|OpenExeConfiguration(String)||Opens the specified client configuration file as a Configuration object.|
|OpenMachineConfiguration||Opens the machine configuration file on the current computer as a Configuration object.|
|OpenMappedExeConfiguration(ExeConfigurationFileMap, ConfigurationUserLevel)||Opens the specified client configuration file as a Configuration object that uses the specified file mapping and user level.|
|OpenMappedExeConfiguration(ExeConfigurationFileMap, ConfigurationUserLevel, Boolean)||Opens the specified client configuration file as a Configuration object that uses the specified file mapping, user level, and preload option.|
|OpenMappedMachineConfiguration||Opens the machine configuration file as a Configuration object that uses the specified file mapping.|
|RefreshSection||Refreshes the named section so the next time that it is retrieved it will be re-read from disk.|
The class enables you to access machine, application, and user configuration information. This class replaces the ConfigurationSettings class, which is deprecated. For web applications, use the WebConfigurationManager class.
To use the class, your project must reference the System.Configuration assembly. By default, some project templates, like Console Application, do not reference this assembly so you must manually reference it.
The name and location of the application configuration file depend on the application's host. For more information, see Application Configuration Files.
You can use the built-in System.Configuration types or derive from them to handle configuration information. By using these types, you can work directly with configuration information and you can extend configuration files to include custom information.
The class includes members that enable you to perform the following tasks:
Read a section from a configuration file. To access configuration information, call the GetSection method. For some sections such as appSettings and connectionStrings, use the AppSettings and ConnectionStrings classes. These members perform read-only operations, use a single cached instance of the configuration, and are multithread aware.
Read and write configuration files as a whole. Your application can read and write configuration settings at any level, for itself or for other applications or computers, locally or remotely. Use one of the methods provided by the class to open a configuration file such as SampleApp.exe.config. These methods return a Configuration object that in turn exposes methods and properties you can use to work with the associated configuration files. The methods perform read or write operations and create the configuration data every time that a file is written.
Support configuration tasks. The following types are used to support various configuration tasks:
In addition to working with existing configuration information, you can create and work with custom configuration elements by extending the built-in configuration types such as the ConfigurationElement, ConfigurationElementCollection, ConfigurationProperty, and ConfigurationSection classes. For an example of how to extend a built-in configuration type programmatically, see ConfigurationSection. For an example of how to extend a built-in configuration type that uses the attribute-based model, see ConfigurationElement.
The Configuration class enables programmatic access for editing configuration files. You use one of the Open methods provided by . These methods return a Configuration object, which in turn provides the required methods and properties to handle the underlying configuration files. You can access these files for reading or writing.
Read permission on the configuration file at the current configuration hierarchy level.
Read permissions on all the parent configuration files.
If your application needs read-only access to its own configuration, we recommend that you use the GetSection method. This method provides access to the cached configuration values for the current application, which has better performance than the Configuration class.
To write to the configuration files, use one of the Save methods. The user or process that writes must have the following permissions:
Write permission on the configuration file and directory at the current configuration hierarchy level.
Read permissions on all the configuration files.
The first example shows a simple console application that reads application settings, adds a new setting, and updates an existing setting.
The previous example assumes your project has an App.config file as shown below.
<?xml version="1.0" encoding="utf-8" ?> <configuration> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" /> </startup> <appSettings> <add key="Setting1" value="May 5, 2014"/> <add key="Setting2" value="May 6, 2014"/> </appSettings> </configuration>
The following example shows how to use a connection string to read data from a database.
The previous example assumes your project has an App.config as shown below.
<?xml version="1.0" encoding="utf-8" ?> <configuration> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" /> </startup> <connectionStrings> <add name="WingtipToys" connectionString="Data Source=(LocalDB)\v11.0;Initial Catalog=WingtipToys;Integrated Security=True;Pooling=False" /> </connectionStrings> </configuration>
A Visual Studio Web site project with source code is available to accompany this topic: Download.
The following example shows how to use the class in a console application. The code shows the following:
How to access the appSettings configuration section. If the section does not exist, it is created and added to the configuration file. The example creates the application configuration file if one does not exist.
How to access the Machine.config file to obtain information such as the default connection string, if it is defined, and the sections that are currently configured.
When you create a project, make sure to add a reference to the System.Configuration assembly. This assembly contains the class.
The example works with elements that are similar to the ones illustrated in the following configuration file. These elements are generated the first time that you run the example.
<?xml version="1.0" encoding="utf-8"?> <configuration> <configSections> <section name="consoleSection" type="Samples.Aspnet.ConsoleSection, ConfigurationManager_CS, Version=18.104.22.168, Culture=neutral, PublicKeyToken=null" /> </configSections> <appSettings> <add key="NewKey0" value="Monday, March 30, 2009 1:36:33 PM" /> <add key="NewKey1" value="Monday, March 30, 2009 1:36:40 PM" /> </appSettings> <consoleSection> <consoleElement background="Black" foreground="White" /> </consoleSection> </configuration>