ConfigurationManager.AppSettings ConfigurationManager.AppSettings ConfigurationManager.AppSettings ConfigurationManager.AppSettings Property

Definition

Gets the AppSettingsSection data for the current application's default configuration.

public:
 static property System::Collections::Specialized::NameValueCollection ^ AppSettings { System::Collections::Specialized::NameValueCollection ^ get(); };
public static System.Collections.Specialized.NameValueCollection AppSettings { get; }
member this.AppSettings : System.Collections.Specialized.NameValueCollection
Public Shared ReadOnly Property AppSettings As NameValueCollection
Property Value

Returns a NameValueCollection object that contains the contents of the AppSettingsSection object for the current application's default configuration.

Exceptions

Examples

The first example shows a simple console application that reads application settings, adds a new setting, and updates an existing setting.

using System;  
using System.Configuration;  

namespace ConsoleApplication1  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            ReadAllSettings();  
            ReadSetting("Setting1");  
            ReadSetting("NotValid");  
            AddUpdateAppSettings("NewSetting", "May 7, 2014");  
            AddUpdateAppSettings("Setting1", "May 8, 2014");  
            ReadAllSettings();  
        }  

        static void ReadAllSettings()  
        {  
            try  
            {  
                var appSettings = ConfigurationManager.AppSettings;  

                if (appSettings.Count == 0)  
                {  
                    Console.WriteLine("AppSettings is empty.");  
                }  
                else  
                {  
                    foreach (var key in appSettings.AllKeys)  
                    {  
                        Console.WriteLine("Key: {0} Value: {1}", key, appSettings[key]);  
                    }  
                }  
            }  
            catch (ConfigurationErrorsException)  
            {  
                Console.WriteLine("Error reading app settings");  
            }  
        }  

        static void ReadSetting(string key)  
        {  
            try  
            {  
                var appSettings = ConfigurationManager.AppSettings;  
                string result = appSettings[key] ?? "Not Found";  
                Console.WriteLine(result);  
            }  
            catch (ConfigurationErrorsException)  
            {  
                Console.WriteLine("Error reading app settings");  
            }  
        }  

        static void AddUpdateAppSettings(string key, string value)  
        {  
            try  
            {  
                var configFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);  
                var settings = configFile.AppSettings.Settings;  
                if (settings[key] == null)  
                {  
                    settings.Add(key, value);  
                }  
                else  
                {  
                    settings[key].Value = value;  
                }  
                configFile.Save(ConfigurationSaveMode.Modified);  
                ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name);  
            }  
            catch (ConfigurationErrorsException)  
            {  
                Console.WriteLine("Error writing app settings");  
            }  
        }  
    }  
}  
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>  

Remarks

A AppSettingsSection object contains the contents of the configuration file's appSettings section.

Applies to

See Also