Creating a Custom Web Part Editor in SharePoint 2010

The Microsoft SharePoint 2010 Web Part framework enables users to configure a Web Part through Web Part properties. A default user interface (UI) is given for each Web Part property that is exposed to the user in the Edit Tool pane of the Web Part. For example, a property of type String is rendered as a text box, and an Enum is rendered as a drop-down list box.

This default rendering by the framework does not allow for much customization because the user cannot get a handle to the controls that are rendered. For example, it has the following limitations:

• Control over UI: Numeric and string types are rendered as text boxes, enumeration types are rendered as a drop-down list box, and Boolean types are rendered as check boxes. So, you cannot show an enumeration type as radio buttons instead of a drop-down list box.
  
• Events: Events that are raised by the controls cannot be handled; for example, you cannot enable or disable a drop-down list based on selecting a check box.
  
• Validation: If user input has to be validated, the framework does not provide a way to easily attach a Microsoft ASP.NET validation control to the input control that is generated. For example, you cannot validate a string input for a valid email address through an ASP.NET RegEx validation control.
  

You can overcome these limitations by using custom editor parts. With custom editor parts, you can offer users functionality that can be achieved through ASP.NET user controls. A Web Part can implement custom editor parts that can be loaded when the Web Part is in edit mode, expose a custom UI, handle events, and validate inputs. A Web Part can have more than one custom editor part associated with it.

This article describes the SharePoint 2010 Web Part framework in detail and provides a code sample to show how to create a custom Web Part editor in SharePoint 2010. First, we examine the framework that enables custom editor parts.