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ApplicationSettingsBase Class

Acts as a base class for deriving concrete wrapper classes to implement the application settings feature in Window Forms applications.

System.Object
  System.Configuration.SettingsBase
    System.Configuration.ApplicationSettingsBase

Namespace:  System.Configuration
Assembly:  System (in System.dll)

public abstract class ApplicationSettingsBase : SettingsBase, 
	INotifyPropertyChanged

The ApplicationSettingsBase type exposes the following members.

  NameDescription
Protected methodApplicationSettingsBase()Initializes an instance of the ApplicationSettingsBase class to its default state.
Protected methodApplicationSettingsBase(IComponent)Initializes an instance of the ApplicationSettingsBase class using the supplied owner component.
Protected methodApplicationSettingsBase(String)Initializes an instance of the ApplicationSettingsBase class using the supplied settings key.
Protected methodApplicationSettingsBase(IComponent, String)Initializes an instance of the ApplicationSettingsBase class using the supplied owner component and settings key.
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  NameDescription
Public propertyContextGets the application settings context associated with the settings group. (Overrides SettingsBase.Context.)
Public propertyIsSynchronizedGets a value indicating whether access to the object is synchronized (thread safe). (Inherited from SettingsBase.)
Public propertyItemGets or sets the value of the specified application settings property. (Overrides SettingsBase.Item[String].)
Public propertyPropertiesGets the collection of settings properties in the wrapper. (Overrides SettingsBase.Properties.)
Public propertyPropertyValuesGets a collection of property values. (Overrides SettingsBase.PropertyValues.)
Public propertyProvidersGets the collection of application settings providers used by the wrapper. (Overrides SettingsBase.Providers.)
Public propertySettingsKeyGets or sets the settings key for the application settings group.
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  NameDescription
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetPreviousVersionReturns the value of the named settings property for the previous version of the same application.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitializeInitializes internal properties used by SettingsBase object. (Inherited from SettingsBase.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnPropertyChangedRaises the PropertyChanged event.
Protected methodOnSettingChangingRaises the SettingChanging event.
Protected methodOnSettingsLoadedRaises the SettingsLoaded event.
Protected methodOnSettingsSavingRaises the SettingsSaving event.
Public methodReloadRefreshes the application settings property values from persistent storage.
Public methodResetRestores the persisted application settings values to their corresponding default properties.
Public methodSaveStores the current values of the application settings properties. (Overrides SettingsBase.Save().)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodUpgradeUpdates application settings to reflect a more recent installation of the application.
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  NameDescription
Public eventPropertyChangedOccurs after the value of an application settings property is changed.
Public eventSettingChangingOccurs before the value of an application settings property is changed.
Public eventSettingsLoadedOccurs after the application settings are retrieved from storage.
Public eventSettingsSavingOccurs before values are saved to the data store.
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ApplicationSettingsBase adds the following functionality to the SettingsBase class, which is used by Web-based applications:

  • The ability to detect attributes on a derived, settings wrapper class. ApplicationSettingsBase supports the declarative model used for wrapper class properties, as described later.

  • Higher-level Save and Reload methods.

  • Additional validation events that you can handle to ensure the correctness of individual settings.

In the application settings architecture, to access a group of settings properties you need to derive a concrete wrapper class from ApplicationSettingsBase. The wrapper class customizes ApplicationSettingsBase in the following ways:

  • For every settings property to be accessed, a corresponding strongly typed public property is added to the wrapper class. This property has get and set accessors for read/write application settings, but only a get accessor for read-only settings.

  • Appropriated attributes must be applied to the wrapper class's public properties to indicate characteristics of the settings property, such as the setting's scope (application or user), whether the setting should support roaming, the default value for the setting, the settings provider to be used, and so on. Each property is required to specify its scope, using either ApplicationScopedSettingAttribute or UserScopedSettingAttribute. Application-scoped settings are read-only if the default LocalFileSettingsProvider is used.

The ApplicationSettingsBase class uses reflection to detect these attributes at run time. Most of this information gets passed to the settings provider layer, which is responsible for storage, persistence format, and so on.

When an application has multiple settings wrapper classes, each class defines a settings group. Each group has the following characteristics:

  • A group can contain any number or type of property settings.

  • If the group name is not explicitly set by the decorating the wrapper class with a SettingsGroupNameAttribute, then a name is automatically generated.

By default, all client-based applications use the LocalFileSettingsProvider to provide storage. If an alternate settings provider is desired, then the wrapper class or property must be decorated with a corresponding SettingsProviderAttribute.

For more information about using application settings, see Application Settings for Windows Forms.

The following code example demonstrates the use of application settings to persist the following attributes of the main form: location, size, background color, and title bar text. All of these attributes are persisted as single application settings properties in the FormSettings class, named FormLocation, FormSize, FormBackColor and FormText, respectively. All except for FormText and Size are data bound to their associated form properties and have a default setting value applied using DefaultSettingValueAttribute.

The form contains four child controls that have the following names and functions:

  • A button named btnBackColor used to display the Color common dialog box.

  • A button named btnReload used to Reload the application settings.

  • A button named btnReset used to Reset the application settings.

  • A textbox named tbStatus used to display status information about the program.

Notice that after every execution of the application, an additional period character is appended to the title text of the form.

This code example requires a Form with a ColorDialog class named colorDialog1, and a StatusStrip control with a ToolStripStatusLabel named tbStatus. Additionally, it requires three Button objects named btnReload, btnReset, and btnBackColor.


   partial class Form1 : Form
   {
       private FormSettings frmSettings1 = new FormSettings();

       public Form1()
       {
           InitializeComponent();
       }

       private void Form1_Load(object sender, EventArgs e)
       {
           this.FormClosing += new FormClosingEventHandler(Form1_FormClosing);

           //Associate settings property event handlers.
           frmSettings1.SettingChanging += new SettingChangingEventHandler(
                                               frmSettings1_SettingChanging);
           frmSettings1.SettingsSaving += new SettingsSavingEventHandler(
                                               frmSettings1_SettingsSaving);

           //Data bind settings properties with straightforward associations.
           Binding bndBackColor = new Binding("BackColor", frmSettings1, 
               "FormBackColor", true, DataSourceUpdateMode.OnPropertyChanged);
           this.DataBindings.Add(bndBackColor);
           Binding bndLocation = new Binding("Location", frmSettings1, 
               "FormLocation", true, DataSourceUpdateMode.OnPropertyChanged);
           this.DataBindings.Add(bndLocation);

           // Assign Size property, since databinding to Size doesn't work well.
            this.Size = frmSettings1.FormSize;

           //For more complex associations, manually assign associations.
           String savedText = frmSettings1.FormText;
           //Since there is no default value for FormText.
           if (savedText != null)
               this.Text = savedText;
       }

       private void Form1_FormClosing(object sender, FormClosingEventArgs e)
       {
           //Synchronize manual associations first.
           frmSettings1.FormText = this.Text + '.';
           frmSettings1.FormSize = this.Size;
           frmSettings1.Save();
       }

       private void btnBackColor_Click(object sender, EventArgs e)
       {
           if (DialogResult.OK == colorDialog1.ShowDialog())
           {
               Color c = colorDialog1.Color;
               this.BackColor = c;
           }
       }

       private void btnReset_Click(object sender, EventArgs e)
       {
           frmSettings1.Reset();
           this.BackColor = SystemColors.Control;
       }

       private void btnReload_Click(object sender, EventArgs e)
       {
           frmSettings1.Reload();
       }

       void frmSettings1_SettingChanging(object sender, SettingChangingEventArgs e)
       {
           tbStatus.Text = e.SettingName + ": " + e.NewValue;
       }

       void frmSettings1_SettingsSaving(object sender, CancelEventArgs e)
       {
           //Should check for settings changes first.
           DialogResult dr = MessageBox.Show(
                           "Save current values for application settings?",
                           "Save Settings", MessageBoxButtons.YesNo);
           if (DialogResult.No == dr)
           {
               e.Cancel = true;
           }
       }

   }

   //Application settings wrapper class
   sealed class FormSettings : ApplicationSettingsBase
   {
       [UserScopedSettingAttribute()]
       public String FormText
       {
           get { return (String)this["FormText"]; }
           set { this["FormText"] = value; }
       }

       [UserScopedSettingAttribute()]
       [DefaultSettingValueAttribute("0, 0")]
       public Point FormLocation
       {
           get { return (Point)(this["FormLocation"]); }
           set { this["FormLocation"] = value; }
       }

       [UserScopedSettingAttribute()]
       [DefaultSettingValueAttribute("225, 200")]
       public Size FormSize
       {
           get { return (Size)this["FormSize"]; }
           set { this["FormSize"] = value; }
       }


       [UserScopedSettingAttribute()]
       [DefaultSettingValueAttribute("LightGray")]
       public Color FormBackColor
       {
           get { return (Color)this["FormBackColor"]; }
           set { this["FormBackColor"] = value; }
       }

   }



.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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