ASP.NET 4 Unleased - p 36 pps

Text=”Did you know that ASP.NET is the newest Microsoft technology for building Web applications?” Runat=”server” /> Creating a Multipage Wizard This final section discusses how you can

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break;

}

</script>

html

{

font:14px Arial,Sans-Serif;

}

</style>

<title>Web Survey</title>

</head>

<body>

<div>

<asp:Label

id=”lblLanguage”

Text=”What language do you use to develop Web applications?”

Runat=”server” />

<br />

<asp:DropDownList

id=”ddlLanguage”

ToolTip=”Web application language (reloads form)”

AutoPostBack=”true”

Runat=”server”>

<asp:ListItem Text=”Select Language” />

<asp:ListItem Text=”ASP Classic” />

<asp:ListItem Text=”ASP.NET” />

</asp:DropDownList>

<asp:PlaceHolder

id=”PlaceHolder1”

<asp:Button

id=”btnSubmit”

Text=”Submit”

OnClick=”btnSubmit_Click”

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<hr />

<asp:Literal

id=”ltlResults”

</div>

</form>

</body>

</html>

WEB STANDARDS NOTE

The DropDownList control in Listing 7.15 reloads the page automatically when you

select a new option You should never reload a page without warning the user because

this can be confusing for someone who uses an assistive device such as a screen

reader In Listing 7.15, a warning is added to the ToolTip property of the

DropDownList control

Depending on the user’s selection from the DropDownList control, one of two User

controls is loaded in the Page_Load() event handler: ASPSurvey.ascx or

ASPNetSurvey.ascx These controls are contained in Listing 7.16 and Listing 7.17

When you submit the survey form, the btnSubmit_Click() method executes This method

casts the User control loaded in the form to the correct type It casts the User control to

either the ASPSurvey or the ASPNetSurvey type

The page in Listing 7.16 includes two <%@ Reference %> directives These reference

direc-tives enable you to cast the User control to the correct type so that you can access

custom properties of the control such as the KnowSlow and KnowOutdated properties

LISTING 7.16 ASPSurvey.ascx

<%@ Control Language=”C#” ClassName=”ASPSurvey” %>

public bool KnowSlow

{

get { return chkSlow.Checked; }

}

public bool KnowOutdated

{

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get { return chkOutdated.Checked; }

}

</script>

<asp:CheckBox

id=”chkSlow”

Text=”Did you know that ASP Classic is slow?”

<asp:CheckBox

id=”chkOutdated”

Text=”Did you know that ASP Classic is outdated?”

LISTING 7.17 ASPNetSurvey.ascx

<%@ Control Language=”C#” ClassName=”ASPNetSurvey” %>

public bool KnowFast

{

get { return chkFast.Checked; }

}

public bool KnowNewest

{

get { return chkNewest.Checked; }

}

</script>

<asp:CheckBox

id=”chkFast”

Text=”Did you know that ASP.NET is fast?”

<asp:CheckBox

id=”chkNewest”

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Text=”Did you know that ASP.NET is the newest Microsoft

technology for building Web applications?”

Creating a Multipage Wizard

This final section discusses how you can create a multipage wizard by dynamically loading

different User controls into the same page This is going to be a complicated sample, but it

is a realistic sample of situations when you would want to load User controls dynamically

(see Figure 7.6)

FIGURE 7.6 Displaying a wizard with a series of User controls

Imagine that you must create a form with 200 questions in it Displaying all 200

ques-tions to a user in a single form would be overwhelming Instead, it makes more sense to

break the form into multiple pages Each page of questions can be represented with a

User control

First, you need to define an interface, named the IWizardStep interface, which all the User

controls will implement An interface enables you to know, in advance, that a User

control supports a particular set of properties or methods

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NOTE

You need to add the interface in Listing 7.18 to your application’s App_Code folder In

Visual Web Developer, create the interface by selecting Website, Add New Item, select

Class Visual Web Developer prompts you to create the App_Code folder

The IWizardStep interface is contained in Listing 7.18

LISTING 7.18 IWizardStep.cs

public interface IWizardStep

{

void LoadStep();

bool NextStep();

}

The interface in Listing 7.18 contains two methods: LoadStep() and NextStep() The

LoadStep() method is called when a User control is first loaded The NextStep() method

is called when the Next button is clicked in the wizard

The NextStep() method returns a Boolean value If the NextStep() method returns the

value False, the user doesn’t advance to the next wizard step

This wizard consists of the three wizard steps contained in Listing 7.19, Listing 7.20, and

Listing 7.21

LISTING 7.19 WizardSteps\Step1.ascx

<%@ Control Language=”C#” ClassName=”Step1” %>

<%@ Implements Interface=”IWizardStep” %>

public void LoadStep()

{

if (Session[“FirstName”] != null)

txtFirstName.Text = (string)Session[“FirstName”];

if (Session[“LastName”] != null)

txtLastName.Text = (string)Session[“LastName”];

}

public bool NextStep()

{

if (Page.IsValid)

{

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Session[“LastName”] = txtLastName.Text;

return true;

}

return false;

}

</script>

<asp:Label

id=”lblFirstName”

Text=”First Name:”

AssociatedControlID=”txtFirstName”

<asp:RequiredFieldValidator

id=”reqFirstName”

Text=”(required)”

ControlToValidate=”txtFirstName”

<br />

<asp:TextBox

id=”txtFirstName”

<asp:Label

id=”lblLastName”

Text=”Last Name:”

AssociatedControlID=”txtLastName”

id=”reqLastName”

ControlToValidate=”txtLastName”

<br />

<asp:TextBox

id=”txtLastName”

The wizard step in Listing 7.19 contains a simple form that contains Textbox controls

for the user’s first and last name Both TextBox controls are validated with

RequiredFieldValidator controls

The User control in Listing 7.19 implements the IWizardStep interface It contains an

<%@ Implements %> directive at the top of the control

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The LoadStep() method assigns values to the txtFirstName and txtLastName TextBox

controls from Session state The NextStep() method grabs the values from the

txtFirstName and txtLastName TextBox controls and assigns the values to Session state

The second step of the Wizard is contained in Listing 7.20

{

if (Session[“FavoriteColor”] != null)

txtFavoriteColor.Text = (string)Session[“FavoriteColor”];

}

{

if (Page.IsValid)

{

Session[“FavoriteColor”] = txtFavoriteColor.Text;

return true;

}

return false;

}

</script>

<asp:Label

id=”lblFavoriteColor”

Text=”Favorite Color:”

AssociatedControlID=”txtFavoriteColor”

id=”reqFavoriteColor”

ControlToValidate=”txtFavoriteColor”

<br />

<asp:TextBox

id=”txtFavoriteColor”

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The User control in Listing 7.20 also implements the IWizardStep interface In this step,

the user enters a favorite color

The final wizard step is contained in Listing 7.21

{

lblFirstName.Text = (string)Session[“FirstName”];

lblLastName.Text = (string)Session[“LastName”];

lblFavoriteColor.Text = (string)Session[“FavoriteColor”];

}

{

return false;

}

</script>

First Name:

<asp:Label

id=”lblFirstName”

<br />

Last Name:

<asp:Label

id=”lblLastName”

<br />

Favorite Color:

<asp:Label

id=”lblFavoriteColor”

The wizard step in Listing 7.21 displays a summary of answers that the user has provided

in the first two wizard steps (see Figure 7.7) It also implements the IWizardStep interface

Because this is the final wizard step, the NextStep() method always returns the value

False

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The page in Listing 7.22 contains the actual wizard This page loads each of the wizard

steps

LISTING 7.22 Wizard.aspx

<%@ Page Language=”C#” %>

<%@ Import Namespace=”System.Collections.Generic” %>

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

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

private List<String> _wizardSteps = new List<String>();

private Control _currentStep;

/// <summary>

/// The current step in the Wizard

/// </summary>

public int StepIndex

{

get

{

if (ViewState[“StepIndex”] == null)

FIGURE 7.7 Displaying the wizard summary step

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else

return (int)ViewState[“StepIndex”];

}

set

{

ViewState[“StepIndex”] = value;

}

/// <summary>

/// Load the list of wizard steps and load

/// current step

/// </summary>

void Page_Load()

{

_wizardSteps.Add(“~/WizardSteps/Step1.ascx”);

LoadWizardStep();

}

/// <summary>

/// Load the current wizard step

/// </summary>

private void LoadWizardStep()

{

_currentStep = Page.LoadControl(_wizardSteps[StepIndex]);

_currentStep.ID = “ctlWizardStep”;

plhWizardStep.Controls.Clear();

plhWizardStep.Controls.Add(_currentStep);

((IWizardStep)_currentStep).LoadStep();

ltlStep.Text = String.Format(“Step {0} of {1}”, StepIndex + 1,

_wizardSteps.Count);

}

/// <summary>

/// Disable the Previous and Next

/// buttons when appropriate

/// </summary>

void Page_PreRender()

{

btnPrevious.Enabled = StepIndex > 0;

btnNext.Enabled = StepIndex < _wizardSteps.Count - 1;

}

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