ASP.NET 2.0: A Developeramp;#039;s Notebook [Electronic resources] نسخه متنی

4.2. Sort and View Records on Multiple Pages

Note: Want to make the GridView control display records in
multiple pages? Tick a checkbox and consider it done!

By default, the GridView control will display all the records in its data set
on a single page. If you have a large number of records to display,
this is not a very elegant way to display your data. For example, you
might want to display all the employees in your company. If you have
large list of names to display, it is much neater and more efficient
to display the list in multiple pages. You might also want the names
to be displayed in alphabetical order, or to allow the user to jump
to a particular page.

You can now perform all of these functions in the GridView control by
simply selecting some checkboxes. There is no need to write lengthy
code to do any of these mundane tasks.

4.2.1. How do I do that?

To see how easy it is to configure the GridView control to display
records in multiple pages and to allow sorting of fields, you will
use the GridView control created in the last lab and configure it to
perform these additional functions.

Using the project created in the last lab, you will now configure the
GridView control so that the data is displayed in multiple pages.

In the GridView Tasks menu of the GridView
control, select the following checkboxes (see Figure 4-25):

Displays the data in multiple pages

Allows the data to be sorted by fields

Enables rows to be selected

Tip: The Enable Selection option is useful when you need to explicitly
select a row in the GridView control. For example, you might want to
select a row in the GridView control so that the detailed information
in the row can be displayed in another GridView control.If a GridView is configured to allow selection, the
SelectedIndexChanged event of the GridView control will be fired when
the user selects a row in the control.

Figure 4-25. Enabling paging, sorting, and selecting for the GridView control

The GridView control will now look like the one shown in Figure 4-26.

Figure 4-26. The GridView control after the configuration

To make the GridView control look nicer, apply the Sand & Sky
theme (via the Auto Format... link in the GridView Tasks menu).

Press F5 to test the application (see Figure 4-27).
You can now sort the rows by field (by clicking on the field name in
the GridView control), select a particular row (by clicking on the
Select link), as well as display the data in multiple pages.

Figure 4-27. The GridView control with sortable fields, selectable rows, and multiple pages

Tip: GridView supports client-side paging and sorting,
all without needing to refresh the page. To do so, set the
EnableSortingAndPagingCallbacks property of the GridView control to
True. This feature uses the Client Callback manager, which is new in
ASP.NET 2.0.For more information on the Client Callback manager, see Chapter 6.

4.2.2. What about...

...modifying the Paging UI of the GridView
control?

The Paging UI of the GridView control refers to the links that are
displayed to allow users to navigate from one page to another. If
your GridView control is going to display multiple pages, you can
customize the texts displayed in the Paging UI. The Mode property
(within the PagerSettings property) of the GridView control allows
you to display pages in different
formats. The Mode property can take any one of the following values:

NextPrevious

Displays the Next and Previous symbols; e.g., < >

Numeric

Displays the page number; e.g., 1 2 3 4 ...

NextPreviousFirstLast

Displays the Next, Previous, First and Last symbols; e.g., <<
< > >>

NumericFirstLast

Displays the page number as well as the First and Last symbols; e.g.,
<< ... 4 5 6 ... >>

The PagerSettings property also exposes the following properties:

FirstPageText

NextPageText

PageButtonCount

Position

PreviousPageText

Figure 4-28 shows how the various properties
configure the paging UI of the GridView control.

Figure 4-28. The properties in the GridView control affecting the paging UI

In addition, you can use images for navigation purposes using the
following properties (simply set these properties to point to the
path containing the images to be used):

Note: You can use custom images for the paging UI.

FirstPageImageUrl

LastPageImageUrl

PreviousPageImageUrl

NextPageImageUrl

4.2.3. Where can I learn more?

If you want to learn how paging and sorting works in the old
DataGrid, check out the DataGrid Girl site
(http://datagridgirl.com/), a
popular site that covers all things DataGrid. Who
knows, after visiting that site you might be even be more impressed
with the GridView control!