ASP.NET 4 Unleashed

Varying the Output Cache by Control

The VaryByControl attribute enables you to generate different cached versions of a page depending on the value of a particular control in the page. This attribute is useful when you need to create a single-page Master/Details form.

For example, the page in Listing 29.4 contains both a DropDownList and GridView control. When you select a new movie category from the DropDownList, a list of matching movies displays in the GridView (see Figure 29.3).

Figure 29.3. Displaying a single-page Master/Details form.

Listing 29.4. MasterDetails.aspx

The page in Listing 29.4 contains an <%@ OutputCache %> directive. ...