ASP.NET 4 Unleased - p 11 pptx

Finally, the TextBox control supports the Focus method.. You can use the Focus method to shift the initial form focus to a particular TextBox control.. If you want to make it easier for

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AutoCompleteType=”LastName”

Runat=”server” />

<asp:Button

id=”btnSubmit”

Text=”Submit”

</div>

</form>

</body>

</html>

FIGURE 2.7 Using AutoComplete with the TextBox control

NOTE

When using Internet Explorer, you can configure AutoComplete by selecting Tools,

Internet Options, Content, and clicking the AutoComplete button The ASP.NET Framework

does not support AutoComplete for other browsers such as FireFox or Opera

Finally, the TextBox control supports the Focus() method You can use the Focus()

method to shift the initial form focus to a particular TextBox control By default, no form

field has focus when a page first opens If you want to make it easier for users to complete

a form, you can set the focus automatically to a particular TextBox control contained in a

form

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For example, the page in Listing 2.9 sets the focus to the first of two form fields

LISTING 2.9 TextBoxFocus.aspx

<%@ Page Language=”C#” %>

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

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

void Page_Load()

{

txtFirstName.Focus();

}

</script>

<title>TextBox Focus</title>

</head>

<body>

<div>

<asp:Label

id=”lblFirstName”

Text=”First Name:”

AssociatedControlID=”txtFirstName”

<br />

<asp:TextBox

id=”txtFirstName”

AutoCompleteType=”FirstName”

<asp:Label

id=”lblLastname”

Text=”Last Name:”

AssociatedControlID=”txtLastName”

<br />

<asp:TextBox

id=”txtLastName”

AutoCompleteType=”LastName”

<asp:Button

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id=”btnSubmit”

Text=”Submit”

</div>

</form>

</body>

</html>

In Listing 2.9, the Page_Load() event handler sets the form focus to the txtFirstName

TextBox control

NOTE

You can also set the form focus by setting either the Page.SetFocus() method or the

server-side HtmlForm control’s DefaultFocus property

Using the CheckBox Control

The CheckBox control enables you to display, well, a check box The page in Listing 2.10

illustrates how you can use the CheckBox control in a newsletter signup form (see

Figure 2.8)

LISTING 2.10 ShowCheckBox.aspx

protected void btnSubmit_Click(object sender, EventArgs e)

{

lblResult.Text = chkNewsletter.Checked.ToString();

}

</script>

<title>Show CheckBox</title>

</head>

<body>

<div>

<asp:CheckBox

id=”chkNewsletter”

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Text=”Receive Newsletter?”

<br />

<asp:Button

id=”btnSubmit”

Text=”Submit”

OnClick=”btnSubmit_Click”

<hr />

<asp:Label

id=”lblResult”

</div>

</form>

</body>

</html>

FIGURE 2.8 Displaying a CheckBox control

In Listing 2.10, the Checked property determines whether the user has checked the check

box Notice that the CheckBox includes a Text property that labels the CheckBox If you use

this property, the proper (accessibility standards-compliant) HTML <label> tag is

gener-ated for the TextBox

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The CheckBox control supports the following properties (this is not a complete list):

server automatically when the CheckBox is checked or unchecked

Text—Enables you to provide a label for the check box

and Right

The CheckBox control also supports the following method:

And the CheckBox control supports the following event:

Notice that the CheckBox control, like the TextBox control, supports the AutoPostBack

property The page in Listing 2.11 illustrates how you can use the AutoPostBack property

to post the form containing the check box back to the server automatically when the

check box is checked or unchecked

LISTING 2.11 CheckBoxAutoPostBack.aspx

protected void chkNewsletter_CheckedChanged(object sender, EventArgs e)

{

lblResult.Text = chkNewsletter.Checked.ToString();

}

</script>

<title>CheckBox AutoPostBack</title>

</head>

<body>

<div>

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<asp:CheckBox

id=”chkNewsletter”

Text=”Receive Newsletter?”

AutoPostBack=”true”

OnCheckedChanged=”chkNewsletter_CheckedChanged”

<hr />

<asp:Label

id=”lblResult”

</div>

</form>

</body>

</html>

NOTE

The ASP.NET Framework also includes the CheckBoxList control that enables you to

display a list of check boxes automatically This control is discussed in detail in

Chapter 10, “Using List Controls.”

Using the RadioButton Control

You always use the RadioButton control in a group Only one radio button in a group of

RadioButton controls can be checked at a time

For example, the page in Listing 2.12 contains three RadioButton controls (see Figure 2.9)

LISTING 2.12 ShowRadioButton.aspx

protected void btnSubmit_Click(object sender, EventArgs e)

{

if (rdlMagazine.Checked)

lblResult.Text = rdlMagazine.Text;

if (rdlTelevision.Checked)

lblResult.Text = rdlTelevision.Text;

if (rdlOther.Checked)

lblResult.Text = rdlOther.Text;

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}

</script>

<title>Show RadioButton</title>

</head>

<body>

<div>

How did you hear about our Website?

<ul>

<li>

<asp:RadioButton

id=”rdlMagazine”

Text=”Magazine Article”

GroupName=”Source”

</li>

<li>

<asp:RadioButton

id=”rdlTelevision”

Text=”Television Program”

</li>

<li>

<asp:RadioButton

id=”rdlOther”

Text=”Other Source”

</li>

</ul>

<asp:Button

id=”btnSubmit”

Text=”Submit”

Runat=”server” OnClick=”btnSubmit_Click” />

<hr />

<asp:Label

id=”lblResult”

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</div>

</form>

</body>

</html>

FIGURE 2.9 Displaying RadioButton

The RadioButton controls in Listing 2.12 are grouped together with the RadioButton

control’s GroupName property Only one of the three RadioButton controls can be

checked at a time

The RadioButton control supports the following properties (this is not a complete list):

the server automatically when the radio button is checked or unchecked

Text—Enables you to label the RadioButton control

Right

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The RadioButton control supports the following method:

Focus—Enables you to set the initial form focus to the RadioButton control

Finally, the RadioButton control supports the following event:

CheckedChanged—Raised on the server when the RadioButton is checked or

unchecked

The page in Listing 2.13 demonstrates how you can use the AutoPostBack property with a

group of RadioButton controls and detect which RadioButton control is selected

LISTING 2.13 RadioButtonAutoPostBack.aspx

protected void RadioButton_CheckedChanged(object sender, EventArgs e)

{

RadioButton selectedRadioButton = (RadioButton)sender;

lblResult.Text = selectedRadioButton.Text;

}

</script>

<title>RadioButton AutoPostBack</title>

</head>

<body>

<div>

How did you hear about our Website?

<ul>

<li>

<asp:RadioButton

id=”rdlMagazine”

Text=”Magazine Article”

OnCheckedChanged=”RadioButton_CheckedChanged”

</li>

<li>

<asp:RadioButton

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id=”rdlTelevision”

Text=”Television Program”

</li>

<li>

<asp:RadioButton

id=”rdlOther”

Text=”Other Source”

</li>

</ul>

<hr />

<asp:Label

id=”lblResult”

</div>

</form>

</body>

</html>

In Listing 2.13, when you select a RadioButton control, the page is automatically posted

back to the server, and the value of the Text property of the selected RadioButton control

displays Notice that all three of the RadioButton controls are associated with the same

CheckedChanged event handler The first parameter passed to the handler represents the

particular RadioButton that was changed

NOTE

The ASP.NET Framework also includes the RadioButtonList control, which enables you

to display a list of radio buttons automatically This control is discussed in detail in

Chapter 10

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