Sometime we need to hardcode values into our code, but this is not the best practice since we’ll have to recompile code every time we need to update our application with new hard coded value or changes to such a value. In other word hard coding is bad. .NET Framework addresses this issue with the new way of specifying values that we would hard coded otherwise. In .NET framework we have configuration files where we store values and can access them as need in an object oriented way. System.Configuration is the main name space that will be using to access these variables from configuration files. There are two main classes what sit right on the top. They are: Configuration and ConfigurationManager classes.

Configuration Properties and Methods

 

Name	Description
AppSettings	Gets the AppSettingsSection object
ConnectionStrings	Gets the ConnectionStrings
ContextInformation	Gets the ContextInformation
FilePath	Gets the physical path
GetSection	Returns the specified ConfigurationSection
GetSectionGroup	Returns the specified ConfigurationSectionGroup
HasFile	Indicates whether a configuration file exists
NamespaceDeclared	Gets or sets a value if it has an XML namespace
RootSectionGroup	Gets the ConfigurationSectionGroup for this Configuration object
Save	Writes the configuration settings
SaveAs	Writes the configuration settings

ConfigurationManager Properties and Methods

 

Name	Description
AppSettings	Gets the AppSettingsSection data
ConnectionStrings	Gets the ConnectionStringsSection data
GetSection	Retrieves a specified configuration section
OpenExeConfiguration	Opens the specified client configuration
OpenMachineConfiguration	Opens the Machine Configuration file
OpenMappedExeConfiguration	Opens the specified client configuration
OpenMappedMachineConfiguration	Opens the specified client configuration

//Open app. file
System.Configuration myConfiguration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

//Open machine file
ExeConfigurationFileMap MyMap = new ExeConfigurationFileMap();
MyMap.ExeConfigFilename = @"DBStringOneDemo.exe.config";
System.Configuration myConfiguration = ConfigurationManager.OpenMappedMachineConfiguration(MyMap);

ConfigurationUserLevel Enumeration

 

Name	Description
None	Gets the System.Configuration.Configuration
PerUserRoaming	Gets the roaming System.Configuration.Configuration
PerUserRoamingAndLocal	Gets the local System.Configuration.Configuration

There are several common sense tasks that can be hard coded into configuration file and later on retrieved by the application in an object oriented way. They are:

1. supportedRuntime – determines version of the application.
2. developmentMode – manages GAC for Assembly install/uninstall via DEVPATH. It instructs the CLR to use DEVPATH.
3. codeBase – specifies Assembly in the GAC that we want to use if multiple assemblies are installed in our GAC, we need to specify version and href inside this tag for location.
4. connectionStrings and appSettings – our configuration string for access DB.

Setting up connection string within .config file is done this way

 

<connectionStrings>

    <clear/>

    <addname="AdventureWorksString"

        providerName="System.Data.SqlClient"

        connectionString="Data Source=localhost;Initial

        Catalog=AdventureWorksDB; Integrated Security=true"/>

</connectionString>

Retrieval of connection information is done this way.
String HelloWorldVariable = ConfigurationSettings.AppSettings["Fool"];

There is newer way to access AppSetting and it’s done like that
NameValueCollection MyAppSettings = ConfigurationManager.AppSettings;
Console.WriteLine(MyAppSettings["Fool"]);
Console.WriteLine(MyAppSettings[0]);

In addition AppSetting implement IEnumerable interface that allows having collection of items and traversing them easily.