The PageCatalogPart class serves one very specific purpose on a Web Parts page: it acts as a page catalog to maintain any controls previously added to the page that a user has closed, so that the user can add them back to the page. This control is visible only when a Web page is in catalog display mode, a special view that enables users to add and remove controls on the page. Add a PageCatalogPart control to your page if you want to provide users with the flexibility of closing and reopening controls. If your page does not allow users to close controls at all, there is no need to add a PageCatalogPart control to your page.
Only closed controls are added to the page catalog. A closed control has several attributes:
It is not visible on the page.
It is not rendered on the page.
It does not participate in page life-cycle phases.
Closing a control is different from deleting it, which permanently removes it from the page. A user can reopen a closed control instance from a page catalog, but after a user deletes a control, he or she can never recover that specific instance.
The most common and convenient way to add a PageCatalogPart control to a page is by declaring it in page persistence format. As with any declarative CatalogPart control, a PageCatalogPart control must be declared within the proper context of ASP.NET markup elements on a Web page. For a working code example of how to declare a PageCatalogPart control in a Web page, see the Example section of this topic. You must add the following sequence of declarative elements to the page:
An <asp:catalogzone> element must be declared, and a child <zonetemplate> element must be added to it to contain any CatalogPart controls declared in the zone.
An <asp:pagecatalogpart> element must be added as a child of the <zonetemplate> element. There might also be other CatalogPart controls declared as child elements of the <zonetemplate> element, including DeclarativeCatalogPart or ImportCatalogPart controls.
The PageCatalogPart class has only one usable property, the Title property, which overrides the base property so that a default title can be provided for the page catalog if no value is supplied.
The remaining properties for the PageCatalogPart class override the inherited properties, but are not actually used for rendering the control. They are overridden only so that special code attributes can be set on them to hide them from design tools like Microsoft Visual Studio 2005. You should not use these hidden properties, because they have no effect on rendering. The fact that they are hidden from IntelliSense and the Properties pane in Visual Studio helps developers avoid using them by mistake. All these hidden properties are noted as such in their respective Help topics.
The PageCatalogPart class also has several important methods. The GetAvailableWebPartDescriptions method retrieves a WebPartDescription object for each WebPart control in the page catalog, which enables a PageCatalogPart control to display information about each server control without having to create an instance of that control. Another method is the GetWebPart method. This method gets an instance of a particular WebPart control, based on the description passed to the method.
Accessibility
The markup rendered by default for this control might not conform to accessibility standards such as the Web Content Accessibility Guidelines 1.0 (WCAG) priority 1 guidelines. For details about accessibility support for this control, see ASP.NET Controls and Accessibility.