ASP.NET 4 Unleased - p 58 potx

EditItemTemplate for the Title column includes a RequiredFieldValidator control.. InsertItemTemplate—The contents of this template display when a new data item is inserted does not apply

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ptg CHAPTER 11 Using the GridView Control

LISTING 11.27 ShowTemplateField.aspx

<%@ Page Language=”C#” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”

“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>

<title>Show TemplateField</title>

</head>

<body>

<div>

<asp:GridView

id=”grdMovies”

DataSourceID=”srcMovies”

DataKeyNames=”Id”

AutoGenerateColumns=”false”

AutoGenerateEditButton=”true”

Runat=”server”>

<asp:TemplateField HeaderText=”Title”>

FIGURE 11.19 Using TemplateFields with the GridView control

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<%# Eval(“Title”) %>

</ItemTemplate>

<asp:TextBox

id=”txtTitle”

Text=’<%# Bind(“Title”) %>’

Runat=”server” />

<asp:RequiredFieldValidator

id=”valTitle”

ControlToValidate=”txtTitle”

Text=”(required)”

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText=”Category”>

<%# Eval(“Name”) %>

</ItemTemplate>

<asp:DropDownList

id=”ddlCategory”

DataSourceID=”srcMovieCategories”

DataTextField=”Name”

DataValueField=”Id”

SelectedValue=’<%# Bind(“CategoryId”) %>’

</EditItemTemplate>

</Columns>

</asp:GridView>

<asp:SqlDataSource

id=”srcMovies”

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

SelectCommand=”SELECT Movies.Id, Title, CategoryId, Name

FROM Movies JOIN MovieCategories

ON MovieCategories.Id = Movies.CategoryId”

UpdateCommand=”UPDATE Movies SET Title=@Title, CategoryId=@CategoryId

WHERE Id=@Id”

<asp:SqlDataSource

id=”srcMovieCategories”

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

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CHAPTER 11 Using the GridView Control

SelectCommand=”SELECT Id, Name FROM MovieCategories”

</div>

</form>

</body>

</html>

GridView in Listing 11.27 contains two TemplateFields The first TemplateField enables

you to display and edit the value of the Title column The contents of ItemTemplate

display when a row is not selected for editing The contents of EditItemTemplate display

when the row is selected for editing.

EditItemTemplate for the Title column includes a RequiredFieldValidator control This

RequiredFieldValidator control prevents a user from updating a record without entering

a value for the Title column

The second TemplateField displays the value of the movie category column

EditItemTemplate contains a DropDownList control, which enables you to change the

movie category associated with the record being edited

TemplateField supports the following six types of templates:

AlternatingItemTemplate—The contents of this template display for every other

row rendered by GridView

EditItemTemplate—The contents of this template display when a row is selected for

editing

FooterTemplate—The contents of this template display in the column footer

HeaderTemplate—The contents of this template display in the column header

InsertItemTemplate—The contents of this template display when a new data item is

inserted (does not apply to the GridView control)

ItemTemplate—The contents of this template display for every row rendered by the

GridView

Working with GridView Control Events

The GridView control includes a rich set of events that you can handle to customize the

control’s behavior and appearance These events can be divided into three groups

First, the GridView control supports the following set of events raised when the control

displays its rows:

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DataBinding—Raised immediately before GridView is bound to its data source

DataBound—Raised immediately after GridView is bound to its data source

RowCreated—Raised when each row in GridView is created

RowDataBound—Raised when each row in GridView is bound to data

Second, the GridView control includes the following set of events raised when you edit

records:

RowCommand—Raised when an event is raised by a control contained in GridView

RowUpdating—Raised immediately before GridView updates a record

RowUpdated—Raised immediately after GridView updates a record

RowDeleting—Raised immediately before GridView deletes a record

RowDeleted—Raised immediately after GridView deletes a record

RowCancelingEdit—Raised when you cancel updating a record

Finally, the GridView control supports the following events related to sorting, selecting,

and paging:

PageIndexChanging—Raised immediately before the current page changes

PageIndexChanged—Raised immediately after the current page changes

Sorting—Raised immediately before sorting

Sorted—Raised immediately after sorting

SelectedIndexChanging—Raised immediately before a row is selected

SelectedIndexChanged—Raised immediately after a row is selected

In this section, you learn how to handle the RowDataBound event (my favorite event

included with the GridView control) to create GridView special effects You learn how to

handle the RowDataBound event to highlight particular rows and show column summaries,

and create nested Master/Detail forms

Imagine that you want to highlight particular rows in GridView For example, when

displaying a table of sales totals, you might want to highlight the rows in which the sales

are greater than a certain amount

You can modify the appearance of individual rows in a GridView control by handling

the RowDataBound event For example, the page in Listing 11.28 displays every movie

that has a box office total greater than $300,000.00 with a yellow background color (see

Figure 11.20)

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ptg CHAPTER 11 Using the GridView Control

LISTING 11.28 HighlightRows.aspx

protected void grdMovies_RowDataBound(object sender, GridViewRowEventArgs e)

{

if (e.Row.RowType == DataControlRowType.DataRow)

{

decimal boxOfficeTotals = (decimal)DataBinder.Eval(e.Row.DataItem,

“BoxOfficeTotals”);

if (boxOfficeTotals > 300000000)

e.Row.BackColor = System.Drawing.Color.Yellow;

}

</script>

<title>Highlight Rows</title>

</head>

FIGURE 11.20 Highlighting rows in the GridView control

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<body>

<div>

<asp:GridView

id=”grdMovies”

OnRowDataBound=”grdMovies_RowDataBound”

Runat=”server”>

<asp:BoundField

DataField=”Title”

HeaderText=”Title” />

<asp:BoundField

DataField=”BoxOfficeTotals”

DataFormatString=”{0:c}”

HtmlEncode=”false”

HeaderText=”Box Office Totals” />

</Columns>

</asp:GridView>

<asp:SqlDataSource

id=”srcMovies”

ConnectionString=”<%$ ConnectionStrings:Movies %>”

SelectCommand=”SELECT * FROM Movies”

</div>

</form>

</body>

</html>

In Listing 11.28, the grdMovies_RowDataBound() method is executed when GridView

renders each of its rows (including its header and footer) The second parameter passed to

this event handler is an instance of the GridViewRowEventArgs class This class exposes a

GridViewRow object that represents the row being bound

The GridViewRow object supports several useful properties (this is not a complete list):

Cells—Represents the collection of table row cells associated with the row being

bound

DataItem—Represents the data item associated with the row being bound

DataItemIndex—Represents the index of the data item in its DataSet associated with

the row being bound

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RowIndex—Represents the index of the row being bound

RowState—Represents the state of the row being bound Possible values are

Alternate, Normal, Selected, and Edit Because these values can be combined (for

example, RowState can be Alternate Edit), use a bitwise comparison RowState

RowType—Represents the type of row being bound Possible values are DataRow,

Footer, Header, NullRow, Pager, and Separator

In Listing 11.28, the RowType property verifies that the row is DataRow (not a header row

or some other type of row) The DataItem property retrieves the database record associated

with the row The DataBinder.Eval() method retrieves the value of the BoxOfficeColumn

Displaying Column Summaries

Imagine that you want to display a column total at the bottom of a column In that case,

you can handle the GridView RowDataBound event to sum the values in a column and

display the summary in the column footer

For example, the page in Listing 11.29 contains a GridView control that displays a

summary column representing the total box office sales of all movies (see Figure 11.21)

FIGURE 11.21 Displaying a column summary

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LISTING 11.29 SummaryColumn.aspx

private decimal _boxOfficeTotalsTotal = 0;

protected void grdMovies_RowDataBound(object sender, GridViewRowEventArgs e)

{

decimal boxOfficeTotals = (decimal)DataBinder.Eval(e.Row.DataItem,

“BoxOfficeTotals”);

_boxOfficeTotalsTotal += boxOfficeTotals;

}

if (e.Row.RowType == DataControlRowType.Footer)

{

Label lblSummary = (Label)e.Row.FindControl(“lblSummary”);

lblSummary.Text = String.Format(“Total: {0:c}”, _boxOfficeTotalsTotal);

}

</script>

<title>Summary Column</title>

</head>

<body>

<div>

<asp:GridView

id=”grdMovies”

OnRowDataBound=”grdMovies_RowDataBound”

ShowFooter=”true”

Runat=”server”>

<asp:BoundField

DataField=”Title”

HeaderText=”Title” />

<asp:TemplateField HeaderText=”Box Office Totals”>

<%# Eval(“BoxOfficeTotals”, “{0:c}”) %>

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</ItemTemplate>

<asp:Label

id=”lblSummary”

</FooterTemplate>

</Columns>

</asp:GridView>

<asp:SqlDataSource

id=”srcMovies”

ConnectionString=”<%$ ConnectionStrings:Movies %>”

SelectCommand=”SELECT * FROM Movies”

</div>

</form>

</body>

</html>

The GridView control uses a TemplateField to represent the BoxOfficeTotals column The

TemplateField includes a <FooterTemplate> that contains a Label control The

grdMovies_RowDataBound() method displays the total of the box office totals in this Label

control

Displaying Nested Master/Details Forms

You also can handle the RowDataBound event to create nested Master/Details forms The page

in Listing 11.30 displays a list of movie categories and displays a list of matching movies

under each category (see Figure 11.22)

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LISTING 11.30 NestedMasterDetail.aspx

protected void grdMovieCategories_RowDataBound(object sender,

➥GridViewRowEventArgs e)

{

int categoryId = (int)DataBinder.Eval(e.Row.DataItem,”Id”);

SqlDataSource srcMovies = (SqlDataSource)e.Row.FindControl(“srcMovies”);

srcMovies.SelectParameters[“CategoryId”].DefaultValue =

categoryId.ToString();

}

</script>

FIGURE 11.22 Displaying a nested Master/Detail form

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