Transcript Validation Controls, User Controls, Master Pages

Validation Controls, User Controls,
Master Pages
IT533 Lectures
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.
Server Controls
Validation Controls
 Rich, declarative validation
 Validation declared separately from input control
 Extensible validation framework
 Supports validation on client and server
 Server-side validation is always done
 Prevents users from spoofing Web Forms
Server Controls
Validation Controls
 <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
Server Controls
Validation Controls
 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 location
 ErrorMessage is displayed in summary
Server Controls
Validation Controls
 Validation controls are associated with their target
control using the ControlToValidate property
<asp:TextBox id=TextBox1 runat=server />
<asp:RequiredFieldValidator id="Req1"
ControlToValidate="TextBox1"
Text="Required Field" runat=server />
 Can create multiple validation controls with the same
target control
Server Controls
Validation Controls
 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!";
}
}
Server Controls
Validation Controls
 Display property controls layout
 Static: fixed layout, display won’t change if invalid
 Dynamic: dynamic layout
 None: no display; can still use ValidationSummary
and Page.IsValid
 Type property specifies expected data type:
Currency, Date, Double, Integer, String
Server Controls
Validation Controls
 Can force down-level option
 Only server-side validation
<% @ Page Language="c#"
ClientTarget="DownLevel" %>
 http://msdn.microsoft.com/en-us/magazine/bb986074.aspx
Server Controls
Validation Controls
 Demo: ValidationControls1.aspx
 Demonstrates each type of validation control
 <configuration>
<appSettings>
<add
key="ValidationSettings:UnobtrusiveValidationMode"
value="none"/>
</appSettings>
</configuration>
Server Controls
Validation Controls
 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.
Server Controls
Validation Controls
 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.
Server Controls
Validation 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.
Server Controls
Validation Controls
 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 Tip
Setting EnableViewState to False reduces the amount
of data passed to the web server with each request.
Validation Controls Exercise
Validation Controls Exercise
Validation Controls Exercise
Validation Controls Exercise
Master Pages
Creating a Master Page
 The master page defines the elements we want to appear on
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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 Pages
 The markup for a master page is almost identical to that
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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 Pages
 At 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 Pages
 Place the cursor to the left of ContentPlaceHolder and
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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 Pages
Creating a Content Page
 Right click the master page in the Solution Explorer and
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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 Pages
 The 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 Pages
Adding 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 Controls
 ASP.NET provides two ways to create your own server-
side controls
 User Controls: Essentially a mini .aspx file
 Custom Controls: You derive a class from
System.Web.UI.Control
Creating Controls
User 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 controls
 Separate code namespace
 Separate code language
 Can partition work across multiple developers
 Great way to reuse work across multiple pages and
applications
Why Use User Controls?
 Reuse user interface and code
Control1.ascx
Application A
Application B
Page3.aspx
Page1.aspx
Page2.aspx
Adding a User Control
 Registers user control for use on a page
 Use the @ Register directive to include a user
control in an ASP.NET Page
<%@ Register TagPrefix="demo"
TagName="validNum" Src="numberbox.ascx" %>
 Insert the user control in a Web Form
<demo:validNum id="num1" runat="server"/>
 Use Get and Set properties of the user control
num1.pNum = 5; //uses Set
x = num1.pNum; //uses Get
Example User Control
 Create 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.ascx
 Add a Textbox controls with RequiredFieldValidator and
RangeValidator
 Create AfterUserControl.aspx
 Register the user control numberbox.ascx
 Add 2 numberbox controls
 Add a Button that adds the pNum properties in these
numberboxes and displays the sum in a Label
Creating Controls
Programmatic 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 Controls
Custom Controls
 A class that you create
 Derived from System.Web.UI.Control
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>”);
}
}
 http://msdn.microsoft.com/en-us/library/zt27tfhy.aspx
Creating Controls
Custom Controls
 Must implement Render() method
 Can expose properties, methods and events
 Should maintain state
 Should handle postback data
 Can generate client-side script to do postback
 Should handle child controls
 Render them
 Handle events
 Can expose and implement templates
 Can handle data binding
Creating Controls
Custom Controls vs. User Controls
User Controls
Custom Controls
Good for application-specific UI
Good 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