Events of the ListView Control in Visual C#.NET

Printing QR Code ISO/IEC18004 in Visual C#.NET Events of the ListView Control

The ListView control has no specific methods worth mentioning. Table 11-3 lists the events that the control fires during its life cycle.

TABLE 11-3

Occurs when the user requests a cancel operation, but before the control cancels the ongoing insert or edit operation. Occurs when the user clicks on any buttons found in the body of the control. Occurs when a new item in the ListView control is being created. Occurs when an item is bound to its data. The two events occur before and after, respectively, the deletion of an item. The operation is requested by the interface of the ListView control. Occurs when an edit operation is requested, but before the ListView switches to the edit template. The two events occur before and after, respectively, the insertion of an item. The operation is requested by the interface of the ListView control. The two events occur before and after, respectively, the update of an item. The operation is requested by the interface of the ListView control. Occurs when the layout template is created. The two events occur before and after, respectively, the properties of a page of data in the ListView control change. A page of data is the set of items that form a page in a paged ListView control. Page properties include page size and start row index. The two events occur before and after, respectively, the ListView control handles the selection of a displayed item and switches to the selected-item template. The two events occur before and after, respectively, the associated data source is sorted.

As you can see, most of the events are related to the life cycle of individual data items. You can control when an item is created, deleted, inserted, or edited. Events fire before and after a given operation is accomplished. So you find doing/done pairs of events for each fundamental operation, such as ItemInserting/ItemInserted or ItemDeleting/ItemDeleted events. You can determine which item type is being created by using the ItemType property on the event data structure. Feasible values are DataItem, InsertItem, and EmptyItem. These values belong to the ListViewItemType enumerated type. The ListView control also features typical events of ASP.NET controls such as Init, Load, PreRender, DataBinding, and Unload. You can handle these events the same way you handle them for other ASP.NET controls.

predefined method. This typically occurs if you define custom buttons in one of the templates. You do not need to handle this event to intercept any clicking on the Edit or Insert button.

The view controls introduced with previous versions of ASP.NET solved many problems that developers were facing every day. Controls such as GridView and DetailsView make it a snap to create a list of records and even arrange a master/detail view. However, they offer limited control over the actual markup generated. Want an example With a GridView control, placing a TBODY tag around the group of child rows is not a trivial task. And it is almost impossible to do with a DataGrid control, unless you resort to your most advanced skills and take on the tough task of deriving a custom grid control. On the other hand, adapting the final markup to the actual needs would be quite a simple task if the view controls introduced with earlier versions of ASP.NET provided a bit more programmatic control over the rendering process and templating. This is just one of the key capabilities you gain with the ListView control. As you ll see in a moment, the ListView control is flexible enough to render out in a tabular or tiled manner. It can be used to replace the GridView control, at least in relatively common situations, but also to create completely custom layouts. This said, let s briefly compare the ListView control to the other view controls available in ASP.NET to see exactly what each control can do and cannot do. Table 11-4 lists and briefly describes the view controls.

TABLE 11-4