10.1 Shared Properties and Collections

Before delving into the specifics of each list-bound control, this chapter will examine the features all three controls share in common.

10.1.1 DataSource

All the list-bound controls have a DataSource property. This property defines the source for data binding, as you've seen earlier with other controls. A DataSource can be any object that implements the System.Collections.ICollection interface: an array, a dataset, or some other homogeneous collection of objects. Often, the data source will be a System.Data.Dataview object, as discussed in Chapter 11. For simplicity, in this chapter you will continue to use an ArrayList object, though you can use any object that implements System.Collections.ICollection, such as a HashTable or an Array object.

10.1.2 Items

The three list-bound controls also contain an Items property that returns a collection of objects representing an item (row) in the data source collection. You use the Items collection to manipulate the items in the list control programmatically.

The Repeater control's Items property returns a collection of RepeaterItem objects, the DataList control's Items property returns a collection of DataListItem objects, and the DataGrid control's Items property returns DataGridItem objects.

The Items collection has an ItemType property that returns an enumerated ListItemType. The members of the ListItemType enumeration are shown in Table 10-2.

Table 10-2. Members of the ListItemType enumeration

List item type	Purpose
AlternatingItem	Every other item
EditItem	Used for in-place editing; see Chapter 13
Footer	Display footer for control
Header	Display header information for control
Item	Displays information about data item
Pager	Display paging information
SelectedItem	The item the user has selected
Separator	Appears between items

Manipulation of the various types of members of the Items collection will be demonstrated throughout the rest of this chapter.

All of the list-bound controls follow the explicit binding method. When its DataBind method is called, the list-bound control enumerates its data source, creating DataListItems and initializing them from the DataSource items. The DataListItem objects are then added to the list-bound control's Items collection. Because this happens only on demand, there are fewer round trips to the server than might otherwise be expected.