ASP.NET 4 Unleased - p 71 pps

Editing Database Data You can use the ListView control to update, delete, and insert items.. The page in Listing 14.6 illustrates how you can use the ListView to modify or delete the rec

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Text=”Title”

CommandName=”Sort”

CommandArgument=”Title”

Runat=”server” />

</th>

<th>

<asp:LinkButton id=”LinkButton1”

Text=”Director”

CommandName=”Sort”

CommandArgument=”Director”

</th>

</tr>

</thead>

</tbody>

</table>

</LayoutTemplate>

<tr>

</tr>

</ItemTemplate>

No records found

</EmptyDataTemplate>

</asp:ListView>

<asp:SqlDataSource

id=”srcMovies”

SelectCommand=”SELECT Id, Title, Director FROM Movie”

ConnectionString=’<%$ ConnectionStrings:con %>’

</div>

</form>

</body>

</html>

The two LinkButtons used for sorting the items in the ListView are contained in the

LayoutTemplate Both LinkButtons have a CommandName property set to the value Sort

The first LinkButton sorts by the Title property and the second LinkButton sorts by the

Director property

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Editing Database Data

You can use the ListView control to update, delete, and insert items The page in Listing

14.6 illustrates how you can use the ListView to modify or delete the records in the Movie

database table (see Figure 14.6)

LISTING 14.6 EditListView.aspx

<%@ Page Language=”C#” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN”

“http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>

.movie

{

border: solid 1px black;

padding:5px;

margin:3px;

}

.edit

FIGURE 14.6 Editing database data with the ListView control

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}

</style>

<title>Edit ListView</title>

</head>

<body>

<div>

<asp:ListView

ID=”lstMovies”

DataSourceId=”srcMovies”

DataKeyNames=”Id”

runat=”server”>

<div id=”itemContainer”

runat=”server”>

</div>

</LayoutTemplate>

<br />

<em>Directed by <%# Eval(“Director”) %></em>

<br />

<asp:LinkButton id=”lnkEdit”

Text=”{Edit}”

CommandName=”Edit”

<asp:LinkButton id=”lnkDelete”

Text=”{Delete}”

CommandName=”Delete”

OnClientClick=”return confirm(‘Delete this movie?’)”

</div>

</ItemTemplate>

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<asp:Label

id=”lblTitle”

Text=”Title:”

AssociatedControlID=”txtTitle”

<br />

<asp:TextBox

id=”txtTitle”

Text=’<%# Bind(“Title”) %>’

<asp:Label

id=”lblDirector”

Text=”Director:”

AssociatedControlID=”txtDirector”

<br />

<asp:TextBox

id=”txtDirector”

Text=’<%# Bind(“Director”) %>’

<asp:LinkButton

id=”lnkUpdate”

Text=”Save”

CommandName=”Update”

<asp:LinkButton

id=”lnkCancel”

Text=”Cancel”

CommandName=”Cancel”

</div>

</EditItemTemplate>

</asp:ListView>

<asp:SqlDataSource

id=”srcMovies”

UpdateCommand=”Update Movie SET Title=@Title, Director=@Director

WHERE Id=@Id”

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DeleteCommand=”Delete Movie WHERE Id=@Id”

</div>

</form>

</body>

</html>

The ListView control in Listing 14 6 has an ItemTemplate that contains two LinkButtons

The first LinkButton has a CommandName property set to the value Edit and the second

LinkButton has a CommandName property set to the value Delete When you click the first

LinkButton, the ListView control’s EditItemTemplate displays When you click the

second LinkButton, the current database record is deleted (after you confirm that you

really want to delete the movie record)

The EditItemTemplate contains a form for editing a movie record The form contains two

TextBox controls that have two-way data-binding expressions assigned to their Text

prop-erties The form also contains two LinkButton controls The first LinkButton control has a

CommandName of Update When you click this button, the database is updated with the

form changes and the EditItemTemplate switches back to the normal ItemTemplate If

you click the Cancel button, the EditItemTemplate switches to an ItemTemplate without

updating the database

When editing with a ListView, you need to assign the primary key column names to the

ListView control’s DataKeyNames property The ListView control uses this to determine

which database record to update

Notice that all the ListView editing is driven by the following magic command names:

Edit, Delete, Update, and Cancel By setting button control CommandName properties to

these magic command names, you can control how the ListView edits items

You also can use the ListView control to insert new records into a database table The

ListView control supports an InsertItemTemplate The page in Listing 14.7 illustrates

how you can use the InsertItemTemplate to create a simple customer feedback form (see

Figure 14.7)

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LISTING 14.7 InsertListView.aspx

<title>Insert ListView</title>

.comment

{

margin:10px;

padding: 10px;

border-left:solid 1px gray;

border-bottom:solid 1px gray;

}

</style>

</head>

<body>

<div>

FIGURE 14.7 Inserting new records with the ListView control

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<asp:ListView

ID=”lstFeedback”

DataSourceId=”srcFeedback”

InsertItemPosition=”FirstItem”

runat=”server”>

<div id=”itemContainer”

runat=”server”>

</div>

</LayoutTemplate>

<%# Eval(“Comment”) %>

</div>

</ItemTemplate>

<div>

Please enter any comments about our website here:

<br />

<asp:Label id=”lblComments”

Text=”Comments:”

AssociatedControlID=”txtComment”

<br />

<asp:TextBox id=”txtComment”

Text=’<%# Bind(“Comment”) %>’

TextMode=”MultiLine”

Columns=”40”

Rows=”3”

<br />

<asp:Button id=”lnkInsert”

Text=”Add Comment”

CommandName=”Insert”

</div>

</InsertItemTemplate>

</asp:ListView>

<asp:SqlDataSource

id=”srcFeedback”

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SelectCommand=”SELECT Id, Comment FROM Feedback”

InsertCommand=”INSERT Feedback (Comment) VALUES (@Comment)”

</div>

</form>

</body>

</html>

The InsertItemTemplate appears only when you set the ListView control’s

InsertItemPosition property You can set this property to the value FirstItem, LastItem,

or None In Listing 14.7, it’s set to the value FirstItem so that the insert form appears

above all the current items

The InsertItemTemplate contains a single TextBox control that has its Text property set

to a data-binding expression The template also contains a Button control that has a

CommandName property set to the value Insert When you click the button, the new item is

inserted into the database

Using the DataPager Control

The DataPager control displays a user interface for navigating through multiple pages of

items The DataPager control works with any control that supports the

IPageableItemContainer interface Unfortunately, there is currently only a single control

that supports this interface: the ListView control So this means that you can only use the

DataPager with the ListView control

The DataPager control includes the following properties:

IPageableItemContainer.)

You set the PageSize to control the number of items to display per page The

PagerControlId property is optional If you place the DataPager within the ListView

control’s LayoutTemplate, you don’t need to set the PagerControlId property If, on the

other hand, you place the DataPager outside of the ListView control, you need to set the

PagerControlId property to the ID of the ListView

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If you add a DataPager to a page and do nothing else, the DataPager won’t render

anything To display a user interface for the DataPager, you need to add one or more

fields to the DataPager The DataPager control supports the following fields:

The page in Listing 14.8 demonstrates how you can use the DataPager control to page

through movies displayed by a ListView control (see Figure 14.8)

LISTING 14.8 DataPagerListView.aspx

<title>DataPager ListView</title>

</head>

<body>

<div>

<asp:ListView

ID=”lstMovies”

DataSourceId=”srcMovies”

runat=”server”>

<ol FIGURE 14.8 Using a DataPager control with the ListView control

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id=”itemContainer”

runat=”server”>

</ol>

<asp:DataPager id=”pg”

PageSize=”2”

Runat=”server”>

<asp:NextPreviousPagerField ShowFirstPageButton=”true”

ShowPreviousPageButton=”true”

ShowNextPageButton=”false”

ShowLastPageButton=”false” />

<asp:NumericPagerField />

<asp:NextPreviousPagerField ShowFirstPageButton=”false”

ShowPreviousPageButton=”false”

ShowNextPageButton=”true”

ShowLastPageButton=”true” />

</Fields>

</asp:DataPager>

</LayoutTemplate>

<li>

<%# Eval(“Title”) %>

</li>

</ItemTemplate>

</asp:ListView>

<asp:SqlDataSource

id=”srcMovies”

</div>

</form>

</body>

</html>

The DataPager contains three fields: NextPreviousPagerField, NumericPagerField, and

NextPreviousPagerField Notice that the DataPager contains two

NextPreviousPagerFields The first one displays the First and Previous links, and the

second one displays the Next and Last links

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