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DesignOnlyAttribute Class

Specifies whether a property can only be set at design time.

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

public sealed class DesignOnlyAttribute : Attribute

Members marked with the DesignOnlyAttribute set to true can be set only at design time. Typically, these properties exist only at design time and do not correspond to a real property on the object at run time.

Members that either have no attribute or are marked with the DesignOnlyAttribute set to false can be set during run time. The default is false.

A property with the DesignOnlyAttribute set to true has its value serialized to the .resx file instead of the InitializeComponent method.

For more information, see Attributes Overview and Extending Metadata Using Attributes.

The following example creates a GetLanguage property. The property is marked with a DesignOnlyAttribute.

 public CultureInfo GetLanguage {
    get {
       // Insert code here. 
       return myCultureInfo;
    set {
       // Insert code here.

The next example gets the value of the DesignOnlyAttribute. First the code gets a PropertyDescriptorCollection with all the properties for the object. Next it indexes into the PropertyDescriptorCollection to find the GetLanguage property. Then it returns the attributes for this property and saves them in the attributes variable.

The example then prints whether the property is design only by retrieving DesignOnlyAttribute from the AttributeCollection, and writing it to the console screen.

// Gets the attributes for the property.
 AttributeCollection attributes = 

 /* Prints whether the property is marked as DesignOnly 
  * by retrieving the DesignOnlyAttribute from the AttributeCollection. */
 DesignOnlyAttribute myAttribute = 
 Console.WriteLine("This property is design only :" +


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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0