it533 lectures validation controls, user controls, master pages

IT533 Lectures

Validation Controls, User Controls,Master Pages

Server Controls Validation Controls

A validation control (or validator) determines whether the data in another web control is in the proper format, before the data is processed.

When the XHTML for our page is created, the validator is converted into JavaScript that performs the validation.

JavaScript is a scripting language that enhances the functionality and appearance of web pages and is typically executed on the client.

Because some clients disable or do not support scripting, ASP.NET validation controls can function on the client,on the server or both.


Rich, declarative validationValidation declared separately from input controlExtensible validation frameworkSupports validation on client and serverServer-side validation is always done

Prevents users from spoofing Web Forms


<asp:RequiredFieldValidator>Ensures that a value is entered

<asp:RangeValidator>Checks if value is within minimum and maximum values

<asp:CompareValidator>Compares value against constant, another control or data

type<asp:RegularExpressionValidator>

Tests if value matches a predefined pattern<asp:CustomValidator>

Lets you create custom client- or server-side validation function

<asp:ValidationSummary>Displays list of validation errors in one place


Validation controls are derived from System.Web.UI.WebControls.BaseValidator, which is derived from the Label control

Validation controls contain text which is displayed only if validation fails

Text property is displayed at control locationErrorMessage is displayed in summary


Validation controls are associated with their target control using the ControlToValidate property

Can create multiple validation controls with the same target control

<asp:TextBox id=TextBox1 runat=server />

<asp:RequiredFieldValidator id="Req1" ControlToValidate="TextBox1" Text="Required Field" runat=server />


Page.IsValid indicates if all validation controls on the page succeed

void Submit_click(object s, EventArgs e) { if (Page.IsValid) { Message.Text = "Page is valid!"; }}


Display property controls layoutStatic: fixed layout, display won’t change if invalidDynamic: dynamic layoutNone: no display; can still use ValidationSummary

and Page.IsValidType property specifies expected data type: Currency, Date, Double, Integer, String


Can force down-level option Only server-side validation

http://msdn.microsoft.com/en-us/magazine/bb986074.aspx

<% @ Page Language="c#" ClientTarget="DownLevel" %>


Demo: ValidationControls1.aspxDemonstrates each type of validation control

<configuration>

<appSettings>

<add key="ValidationSettings:UnobtrusiveValidationMode"

value="none"/>

</appSettings>

</configuration>


The code-behind file validates the information again in case the client has JavaScript disabled.

The submission of a form sends its data to the server and causes the current page to be requested again is called a postback.

The IsPostBack property of class Page determines whether the page is being loaded due to a postback.

The current Page’s Validate method validates the information as specified by the validation controls in the Web Form.


Use the IsValid property of class Page to check whether all the validators succeeded.

You should always call method Validate before using property IsValid.

When data is posted to the web server, the form’s data becomes accessible to the web application through the properties of the various web controls.


Examining the Client-Side XHTML for a Web Form with Validation If a validation control’s EnableClientScript

property is True, the validator performs client-side validation as the user edits the Web Form. You do not need to be able to create or even understand the JavaScript validation code—the validators are converted to working JavaScript by ASP.NET. The EnableViewState attribute determines whether a web control’s current state is remembered each time a postback occurs.


The default value, True, indicates that the control’s state at the last postback is retained.

A hidden input called __VIEWSTATE stores the controls’ data as an encoded string so the server can determine whether it has changed.

Performance TipSetting EnableViewState to False reduces the amount of data passed to the web server with each request.

Validation Controls Exercise

Master PagesCreating a Master PageThe master page defines the elements we want to appear on each

page. A master page is like a base class in a visual inheritance hierarchy.

The master page contains placeholders for custom content created in each content page.

To create a master page, right click the location of the website in the Solution Explorer and select Add New Item….

Select Master Page and specify Bug2Bug.master as the file name.Master pages have the file-name extension .master and, like Web

Forms, can optionally use a code-behind file to define additional functionality.

Leave the box labeled Place code in a separate file unchecked and click Add to create the page.

Master PagesThe markup for a master page is almost identical to that

of a Web Form. A master page contains a Master directive, which

specifies that this file defines a master page using the indicated Language for any code.

Code that would usually be placed in a code-behind file can be placed in a script element.

Next, set the title of the page to Bug2Bug.The master page contains two ContentPlaceHolder

controls for content that will be defined by a content page.

Master PagesAt this point, you can edit the master page in Design

mode as if it were an ASPX file. • The ContentPlaceHolder control appears as a

rectangle with a purple outline indicating the control’s type and ID.

• Using the Properties window, change the ID of this control to bodyContent.

Master PagesPlace the cursor to the left of ContentPlaceHolder and select

Table > Insert Table.In the Insert Table dialog, set Rows to 2 and Columns to 1. In the

Layout section, specify a Cell padding and a Cell spacing of 0.Set both the width and height of the table to 100 percent. Make

sure that the Size value in the Borders section is 0.Click OK to create a table that fills the page and contains two rows.Change the style to have vertical-align property of the

bottom table cell to top and drag the ContentPlaceHolder into this cell.

Set the Height of the top table cell to 130. Add an Image control named headerImage with its ImageUrl property set to the bug2bug.png file.

Bug2Bug.master page that defines a logo image header for all pages

Master PagesCreating a Content PageRight click the master page in the Solution Explorer and

select Add Content Page. Rename the Default.aspx to ContentPage.aspx, then open it in Source mode

The Page directive indicates the MasterPageFile that is used as a starting point for this new page’s design.

The Title property specifies the title that will be displayed in the web browser’s title bar when the content page is loaded.

This value, which we set to Create a New User, replaces the value (i.e., Bug2Bug) set in the title element of the master page.

Because CreateNewUser.aspx specifies Bug2Bug.master as the page’s MasterPageFile, it implicitly contains the contents of the master page.

Master PagesThe content page contains Content controls, in which we

will place page-specific content that will replace the master page’s ContentPlaceHolders.

The ContentPlaceHolderID property of the Content control identifies which ContentPlaceHolder the control should replace

The relationship between a content page and its master page is more evident in Design mode:

Master PagesAdding a CreateUserWizard Control to a Content Page CreateNewUser.aspx is the page in our website that allows first-time visitors to create user accounts. To provide this functionality, we use a CreateUserWizard control.Place the cursor inside the Content control in Design mode and double click CreateUserWizard in the Toolbox to add it to the page. Open the CreateUserWizard Tasks smart-tag menu and click Auto Format. Select the Professional color scheme.When the user clicks the Create User button, ASP.NET verifies that all the form’s requirements were fulfilled and attempts to create the user account. (we will use this next week)In CreateNewUser.aspx, the Page directive indicates that this content page inherits content from Bug2Bug.master.

Creating ControlsASP.NET provides two ways to create your own

server-side controlsUser Controls: Essentially a mini .aspx fileCustom Controls: You derive a class from System.Web.UI.Control

Creating ControlsUser Controls

User controls simplify the reuse of code and UI components within a Web application

A user control is a user-defined Web server control with an .ascx extension

Contains HTML, but not the <HTML>, <BODY>, or <FORM> tags

Enables full encapsulation Supports nested controlsSeparate code namespaceSeparate code language

Can partition work across multiple developersGreat way to reuse work across multiple pages and

applications

Why Use User Controls?Reuse user interface and code

Page2.aspx

Control1.ascx

Page1.aspx

Page3.aspx

Application A Application B

Adding a User ControlRegisters user control for use on a pageUse the @ Register directive to include a user

control in an ASP.NET Page

Insert the user control in a Web Form

Use Get and Set properties of the user control

<%@ Register TagPrefix="demo" TagName="validNum" Src="numberbox.ascx" %><%@ Register TagPrefix="demo" TagName="validNum" Src="numberbox.ascx" %>

<demo:validNum id="num1" runat="server"/> <demo:validNum id="num1" runat="server"/>

num1.pNum = 5; //uses Setx = num1.pNum; //uses Getnum1.pNum = 5; //uses Setx = num1.pNum; //uses Get

Example User ControlCreate BeforeUserControl.aspx

Add 2 Textbox controls with RequiredFieldValidator and RangeValidator

Add a Button that adds the values in these textboxes and displays the sum in a Label

Create a Web User Control numberbox.ascxAdd a Textbox controls with RequiredFieldValidator and RangeValidator

Create AfterUserControl.aspxRegister the user control numberbox.ascxAdd 2 numberbox controlsAdd a Button that adds the pNum properties in these numberboxes and displays the sum in a Label

Creating ControlsProgrammatic Use of User Controls

Page.LoadControl(string source)Dynamically instantiates a user control

Create an instance:Control numbox1 = Page.LoadControl("numberbox.ascx");

Insert into the control hierarchy:myPanel.Controls.Add(foo);

CreateDynamicUserControls.aspx

Creating ControlsCustom Controls

A class that you createDerived from System.Web.UI.Control

http://msdn.microsoft.com/en-us/library/zt27tfhy.aspx

using System;using System.Web;using System.Web.UI;

public class MyControl : Control { protected override void Render(HTMLTextWriter w) { w.Write(“<h1>Control output</h1>”); }}

Creating ControlsCustom Controls

Must implement Render() methodCan expose properties, methods and eventsShould maintain stateShould handle postback data

Can generate client-side script to do postbackShould handle child controls

Render themHandle events

Can expose and implement templatesCan handle data binding

Creating ControlsCustom Controls vs. User Controls

User Controls Custom Controls

Good for application-specific UIGood for reuse, encapsulate common UI

Easy to build Can be more complex to build

Less flexibility, performance, designer support

Total flexibility, better performance, and designer support

No template support Can support templates

it533 lectures validation controls, user controls, master pages

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