ConfigurationManager.AppSettings Property
.NET Framework (current version)
Gets the AppSettingsSection data for the current application's default configuration.
Assembly: System.Configuration (in System.Configuration.dll)
Property Value
Type: System.Collections.Specialized.NameValueCollectionReturns a NameValueCollection object that contains the contents of the AppSettingsSection object for the current application's default configuration.
| Exception | Condition |
|---|---|
| ConfigurationErrorsException | Could not retrieve a NameValueCollection object with the application settings data. |
A AppSettingsSection object contains the contents of the configuration file's appSettings section.
The first example shows a simple console application that reads application settings, adds a new setting, and updates an existing setting.
Imports System.Configuration Module Module1 Sub Main() ReadAllSettings() ReadSetting("Setting1") ReadSetting("NotValid") AddUpdateAppSettings("NewSetting", "May 7, 2014") AddUpdateAppSettings("Setting1", "May 8, 2014") ReadAllSettings() End Sub Sub ReadAllSettings() Try Dim appSettings = ConfigurationManager.AppSettings If appSettings.Count = 0 Then Console.WriteLine("AppSettings is empty.") Else For Each key As String In appSettings.AllKeys Console.WriteLine("Key: {0} Value: {1}", key, appSettings(key)) Next End If Catch e As ConfigurationErrorsException Console.WriteLine("Error reading app settings") End Try End Sub Sub ReadSetting(key As String) Try Dim appSettings = ConfigurationManager.AppSettings Dim result As String = appSettings(key) If IsNothing(result) Then result = "Not found" End If Console.WriteLine(result) Catch e As ConfigurationErrorsException Console.WriteLine("Error reading app settings") End Try End Sub Sub AddUpdateAppSettings(key As String, value As String) Try Dim configFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None) Dim settings = configFile.AppSettings.Settings If IsNothing(settings(key)) Then settings.Add(key, value) Else settings(key).Value = value End If configFile.Save(ConfigurationSaveMode.Modified) ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name) Catch e As ConfigurationErrorsException Console.WriteLine("Error writing app settings") End Try End Sub End Module
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>
.NET Framework
Available since 2.0
Available since 2.0
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