ASP.NET 4 Unleased - p 15 potx

By default, a Panel control renders a tag around its contents.. When enabling scrollbars with the Panel control, you must specify a particular width and height to display the scrollbars

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

DefaultButton—Enables you to specify the default button in a Panel The default

button is invoked when you press the Enter button

Direction—Enables you to get or set the direction in which controls that display

text are rendered Possible values are NotSet, LeftToRight, and RightToLeft

GroupingText—Enables you to render the Panel control as a fieldset with a particular

legend

HorizontalAlign—Enables you to specify the horizontal alignment of the contents

of the Panel Possible values are Center, Justify, Left, NotSet, and Right

ScrollBars—Enables you to display scrollbars around the panel’s contents Possible

values are Auto, Both, Horizontal, None, and Vertical

By default, a Panel control renders a <div> tag around its contents If you set the

GroupingText property, however, the Panel control renders a <fieldset> tag The

value that you assign to the GroupingText property appears in the <fieldset> tag’s

<legend> tag Listing 2.30 demonstrates how you can use the GroupingText property (see

Figure 2.19)

LISTING 2.30 PanelGroupingText.aspx

<%@ Page Language=”C#” %>

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

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

<title>Panel Grouping Text</title>

</head>

<body>

<div>

<asp:Panel

id=”pnlContact”

GroupingText=”Contact Information”

Runat=”server”>

<asp:Label

id=”lblFirstName”

Text=”First Name:”

AssociatedControlID=”txtFirstName”

Runat=”server” />

<br />

<asp:TextBox

id=”txtFirstName”

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AutoCompleteType=”FirstName”

<asp:Label

id=”lblLastname”

Text=”Last Name:”

AssociatedControlID=”txtLastName”

<br />

<asp:TextBox

id=”txtLastName”

AutoCompleteType=”LastName”

<asp:Button

id=”btnSubmit”

Text=”Submit”

</asp:Panel>

</div>

</form>

</body>

</html>

FIGURE 2.19 Setting the GroupingText property

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WEB STANDARDS NOTE

According to the accessibility guidelines, you should use <fieldset> tags when

group-ing related form fields in long forms

The ScrollBars property enables you to display scrollbars around a panel’s contents For

example, the page in Listing 2.31 contains a Panel control that contains a BulletedList

control that displays 100 items The panel is configured to scroll when its contents

over-flow its width or height (see Figure 2.20)

LISTING 2.31 PanelScrollBars.aspx

void Page_Load()

{

for (int i = 0; i < 100; i++)

bltList.Items.Add(“Item “ + i.ToString());

}

</script>

html

{

background-color:silver;

}

.contents

{

background-color:white;

width:200px;

height:200px;

}

</style>

<title>Panel ScrollBars</title>

</head>

<body>

<div>

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<asp:Panel

id=”pnlContent”

ScrollBars=”Auto”

CssClass=”contents”

Runat=”server”>

<asp:BulletedList

id=”bltList”

</asp:Panel>

</div>

</form>

</body>

</html>

FIGURE 2.20 Displaying scrollbars with a Panel control

WEB STANDARDS NOTE

Don’t use the values Horizontal or Vertical with the ScrollBars property when you

want the scrollbars to appear in browsers other than Microsoft Internet Explorer If you

want the scrollbars to appear in FireFox and Opera, use either the value Auto or Both

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When enabling scrollbars with the Panel control, you must specify a particular width and

height to display the scrollbars In Listing 2.31, the width and height are specified in a

Cascading Style Sheet class Alternatively, you can specify the width and height with the

Panel control’s Width and Height properties

The HyperLink control enables you to create a link to a page Unlike the LinkButton

control, the HyperLink control does not submit a form to a server

For example, the page in Listing 2.32 displays a hyperlink that randomly links to a page in

your application

LISTING 2.32 ShowHyperLink.aspx

<%@ Import Namespace=”System.IO” %>

void Page_Load()

{

lnkRandom.NavigateUrl = GetRandomFile();

}

string GetRandomFile()

{

string[] files = Directory.GetFiles(MapPath(Request.ApplicationPath),

➥“*.aspx”);

Random rnd = new Random();

string rndFile = files[rnd.Next(files.Length)];

return Path.GetFileName(rndFile);

}

</script>

<title>Show HyperLink</title>

</head>

<body>

<div>

<asp:HyperLink

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id=”lnkRandom”

Text=”Random Link”

</div>

</form>

</body>

</html>

In the Page_Load event handler in Listing 2.32, a random filename from the current

appli-cation is assigned to the NavigateUrl property of the HyperLink control

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

Enabled—Enables you to disable the hyperlink

ImageUrl—Enables you to specify an image for the hyperlink

NavigateUrl—Enables you to specify the URL represented by the hyperlink

Target—Enables you to open a new window

Text—Enables you to label the hyperlink

Notice that you can specify an image for the HyperLink control by setting the ImageUrl

property If you set both the Text and ImageUrl properties, the ImageUrl property takes

precedence

Summary

In this chapter, you were introduced to the core controls of ASP.NET 4 Framework You

learned how to display information using the Label and Literal controls You also

learned how to accept user input using the TextBox, CheckBox, and RadioButton controls

In the second part of this chapter, you learned how to use the different button controls—

Button, LinkButton, and ImageButton—to submit a form You learned how to post forms

between pages You also learned how to set a default button

Finally, we discussed the Panel and HyperLink controls You learned how to hide and

display a group of controls with the Panel control You also learned how to create

dynamic links with the HyperLink control

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ptg

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Using the Validation

Controls

Overview of the Validation Controls

Using the RequiredFieldValidator Control

Using the RangeValidator Control

Using the CompareValidator Control

Using the RegularExpressionValidator Control

Using the CustomValidator Control

Using the ValidationSummary Control

Creating Custom Validation Controls

Summary

In this chapter, you learn how to validate form fields when

a form is submitted to the web server You can use the

vali-dation controls to prevent users from submitting the wrong

type of data into a database table For example, you can use

validation controls to prevent a user from submitting the

value “Apple” for a birth date field

In the first part of this chapter, you are provided with an

overview of the standard validation controls included in the

ASP.NET 4 Framework You learn how to control how

vali-dation errors display, how to highlight valivali-dation error

messages, and how to use validation groups You are

provided with sample code for using each of the standard

validation controls

Next, we extend the basic validation controls with our own

custom validation controls For example, you learn how to

create an AjaxValidator control that enables you to call a

server-side validation function from the client

Overview of the Validation Controls

ASP.NET 4 includes six validation controls:

RequiredFieldValidator—Enables you to require a

user to enter a value in a form field

RangeValidator—Enables you to check whether a

value falls between a certain minimum and maximum

value

CompareValidator—Enables you to compare a value

against another value or perform a data type check

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RegularExpressionValidator—Enables you to compare a value against a regular

expression

CustomValidator—Enables you to perform custom validation

ValidationSummary—Enables you to display a summary of all validation errors in a

page

You can associate the validation controls with any form controls included in ASP.NET

Framework For example, if you want to require a user to enter a value into a TextBox

control, you can associate a RequiredFieldValidator control with the TextBox control

NOTE

Technically, you can use the validation controls with any control decorated with the

ValidationProperty attribute

Listing 3.1 contains a simple order entry form It contains three TextBox controls that

enable you to enter a product name, product price, and product quantity The validation

controls validate each of the form fields

LISTING 3.1 OrderForm.aspx

void btnSubmit_Click(Object sender, EventArgs e)

{

if (Page.IsValid)

{

lblResult.Text = @”<br />Product: “ + txtProductName.Text

+ “<br />Price: “ + txtProductPrice.Text + “<br />Quantity: “ + txtProductQuantity.Text;

}

</script>

<title>Order Form</title>

</head>

<body>

<div>

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<legend>Product Order Form</legend>

<asp:Label

id=”lblProductName”

Text=”Product Name:”

AssociatedControlID=”txtProductName”

<br />

<asp:TextBox

id=”txtProductName”

<asp:RequiredFieldValidator

id=”reqProductName”

ControlToValidate=”txtProductName”

Text=”(Required)”

<asp:Label

id=”lblProductPrice”

Text=”Product Price:”

AssociatedControlID=”txtProductPrice”

<br />

<asp:TextBox

id=”txtProductPrice”

Columns=”5”

<asp:RequiredFieldValidator

id=”reqProductPrice”

ControlToValidate=”txtProductPrice”

Text=”(Required)”

Display=”Dynamic”

<asp:CompareValidator

id=”cmpProductPrice”

ControlToValidate=”txtProductPrice”

Text=”(Invalid Price)”

Operator=”DataTypeCheck”

Type=”Currency”

Tiêu đề	Using The Standard Controls
Trường học	University of XYZ
Chuyên ngành	Computer Science
Thể loại	Bài luận
Năm xuất bản	2025
Thành phố	City Name

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