ASP.NET Tutorial Michele Leroux Bustamante Get accompanying code samples from the following site: http://www.dotnetdashboard.net/ark/aspnettutorial.aspx IDesign Site: www.idesign.net Newsletter Site: www.dotnetdashboard.net Personal Site: www.mlbtechnologies.com.

Download Report

Transcript ASP.NET Tutorial Michele Leroux Bustamante Get accompanying code samples from the following site: http://www.dotnetdashboard.net/ark/aspnettutorial.aspx IDesign Site: www.idesign.net Newsletter Site: www.dotnetdashboard.net Personal Site: www.mlbtechnologies.com. 

ASP.NET Tutorial
Michele Leroux Bustamante
Get accompanying code samples from the following site:
http://www.dotnetdashboard.net/ark/aspnettutorial.aspx
IDesign Site: www.idesign.net
Newsletter Site: www.dotnetdashboard.net
Personal Site: www.mlbtechnologies.com
Part I: Fundamentals
My First ASP.NET Application
Page Processing & HTML Output
ASP.NET Server Controls
State Management
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
2
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
3
Part I: Fundamentals
My First ASP.NET Application
Page Processing & HTML Output
ASP.NET Server Controls
State Management
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
4
Creating a New Web Application
From VS.NET, create a new VB.NET
or C# Web Application
By default, files are created beneath
localhost,
in a project
subdirectory
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
5
Creating a New Web Application
Project Files Created in
\Inetpub\wwwroot\MyWebApp
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
6
Testing Your New Application
 Compile and run from VS.NET, or…
 Compile, then, in your Web browser, type
the URL:
http://localhost/MyWebApp/WebForm1.aspx
Did you get a blank page? Good!
 Rename the web form file to default.aspx


Both the .cs/.vb file and .aspx file will be renamed
Do this from Solution Explorer!
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
7
Reviewing the HTML
You can rename the Web form class

WebForm1 -> defaultForm
<%@ Page language=“C#” Codebehind=“default.cs” AutoEventWireup=“false”
Inherits=“MyWebApp.WebForm1” %>
namespace
class
.cs file containing code
for this page
<%@ Page language=“vb” Codebehind=“default.vb” AutoEventWireup=“false”
Inherits=“MyWebApp.WebForm1” %>
namespace
class
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
.vb file containing code
for this page
8
Designing Web Pages
Navigating the Visual Studio IDE

HTML designer


HTML code


Where you will drag and drop Web controls
Edit the generated HTML directly
Codebehind


Separate business logic from user interface
Page and Control events can be handled in
codebehind file
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
9
Web Form Architecture
Combines declarative tags…

HTML, XML, WML, static text
…with code

Clean separation between code & tags
code
<tags>
<tags>
Form1.aspx
Form1.aspx
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
code
Form1.vb/.cs
10
Page Design
Toolbox Controls


HTML Controls
ASP.NET Server Controls
Drag & Drop to Design View
Review HTML in HTML View
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
11
HTML Controls
Drag and drop from toolbox
into the HTML designer
Automatically generates HTML
Select controls in designer,
edit in Properties window
<form id=“form1” method=“post” runat=“server>
<INPUT id=“Button1” type=“button” value="Button"
name="Button1" runat="server“>
<INPUT id=“Text1” type=“text” value="Button"
name="Button1" runat="server“>
</form>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
12
DOCUMENT Properties
 Use the Properties window to set
DOCUMENT properties
 Converted to HTML automatically
 Examples:
bgcolor
 Inherits
 pageLayout
 showGrid
 title

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
13
Document Outline Window
HTML Outline
Hierarchical view of HTML code
Select items to find
location in HTML
Delete items easily
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
14
Document Outline Window
Script Outline
Visible in HTML View
List of events for each
"named" HTML control

Use “id” attribute
Can double-click to
create event handlers
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
15
Client Side Script
Project Properties

JavaScript or VBScript
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
16
.ASPX Syntax
 A simple page is just static text & HTML

Any HTML page can be renamed .ASPX
 Pages may also contain:






Directives: <%@ directive %>
Server controls: <tag runat=server>
Code blocks: <script runat=server>
Data bind expressions: <%# expression %>
Server side comments: <%-- --%>
Render code: <%= %> and <% %>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
17
Page Script
<script language="C#" runat="server">
void Page_Load()
{
// add items to the listbox
lst.Items.Add("http://www.dotnetdashboard.net");
lst.Items.Add("http://www.idesign.net");
}
</script>
<form id="PageScript" method="post" runat="server">
<SELECT id="lst" style="Z-INDEX: 101; LEFT: 37px; WIDTH: 416px;
POSITION: absolute; TOP: 60px; HEIGHT: 164px" size="10"
runat="server" name="lst">
<OPTION>Item1</OPTION>
<OPTION>Item2</OPTION>
</SELECT>
</form>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
18
Page Class
 All ASP.NET pages are compiled into
a “stateless” class (object)
 Page class provides access to:

Properties to access ASP.NET server objects
Application,
Cache, Request, Response,
Server, Session

Properties describing page state
EnableViewState,

IsPostBack, IsValid
Events that interact with round trip state
Load,
Unload, PreRender, DataBinding
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
19
Page Events
Page Events




Page_Init – Fired when page is initialized
Page_Load – Fired when page is loaded
Control_Event – Fired if a control event is
triggered
Page_Unload – Fired when page is unloaded
from memory
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
20
Page Load Event
Load event is fired on every request
Should ALWAYS use Page.IsPostBack
property to execute conditional logic
public void Page_Load(object s, EventArgs e)
{
if (!Page.IsPostBack) //executes only on initial page load
Message.Text = “initial value”
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
21
Run As Server Control
HTML controls
must be run as
server controls
for events to be
handled in
Codebehind module
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
22
Codebehind - runat=“server”
HTML Controls can be processed on
the server:
<input id=“txtFirstName” type=“text” runat=“server”>
When the Form is submitted to the
page, we can get it’s value like this:
string strFirstName;
strFirstName = txtFirstName.Text;
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
23
Events
ASP.NET Control Events

HTML View


HTML control events can be handled in script
within the HTML page
Codebehind


Can handle events for ASP Server controls
And, HTML controls run on the server
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
24
Client-Side Events
Only HTML
controls listed
here (if they
have an id)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
25
Client-Side Events
Selected HTML
control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
List of valid
events
26
ASP.NET Controls
Drag and drop from toolbox into the
HTML designer
Automatically generates definition
Placed between form tags in HTML
Select controls in designer, edit
properties in Properties window
<form id=“form1” method=“post” runat=“server>
<asp:TextBox id="TextBox1" runat="server"></asp:TextBox>
<asp:Button id=“Button1" runat="server"></asp:Button>
</form>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
27
Codebehind Module
 Write code to respond to page and
control events
 Use codebehind control members to
manipulate properties of controls
 Code is compiled into the application
assembly

Beneath \bin directory
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
28
HttpRequest Object
Page.Request property
Use it to access:



Form parameters
QueryString parameters
Request headers and content
NOTE: You can save the contents of
the HttpRequest by using the
SaveAs() method!
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
29
HttpResponse Object
 Use Page.Response property to access:


Output stream
Output cache
 Send data back to the browser
 BufferOutput property


Set to true, response is not sent until buffer is flushed
Set to false, Response.Write statements are flushed
to client
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
30
ASP.NET Application Files
 VS.NET creates default set of ASP.NET
project files
 .csproj or .vbproj

Your project file, stores list of project files settings
 .webinfo

Project file indicating the URL for the Web application
based on IIS path (edit if project is moved)
 .sln


Solution file, can load more than one project
VS.NET will load the solution
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
31
ASP.NET Application Files
 Web.config


Can customize application configuration settings
Can override Machine.config settings
 Global.asax


Represents the HttpApplication object
Can write code for application-level events
 *.aspx




Default Web forms is WebForm1.aspx
Inherits the Page class
Can add more pages, and rename them as desired
Must select 1 to be the “startup” page
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
32
Global.asax
 Inherits HttpApplication
 Provides access to the application instance
during an HTTP request
 @ Application directive links to codebehind
<%@ Application Codebehind="Global.asax.vb"
Inherits="ViewState.Global" %>
 Like .aspx files, .asax can include:


Server side <script> tags
Object creation <object> tags
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
33
Global.asax
Can handle application and
HttpModule events
For example, SessionStateModule
Application.Start
Session.Start
Application.BeginRequest
Application.EndRequest
Session.End
Application.End
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
34
Part I: Fundamentals
My First ASP.NET Application
Page Processing & HTML Output
ASP.NET Server Controls
State Management
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
35
Page Class
Page class is dynamically compiled
by ASP.NET
Requests are handled by instance
HTML is written to the response
stream by the page
*.aspx
Page Object
Codebehind
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
36
*.ASPX Files
 Defaults to Codebehind
 Can modify @ Page directive
 Benefits of Codebehind




Intermediate Language (IL) compiler can catch errors
*.ASPX are JIT compiled, users see uncaught errors
Clean separation of business logic and user interface
presentation with a preserved event-driven model
Event validation controls perform client-side work, no
need for in-page scripting (most of the time)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
37
Codebehind
Codebehind inherits
System.Web.UI.Page
Can handle Page events of interest
Page.Init
Page.Load
Page_DataBinding
Page.PreRender
Page.Unload
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
38
Page Events
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
39
The Round Trip
HTTP Request
HTTP Response
Render
Page and
Control
HTML
Page Object
Render
Control
HTML
Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
40
The Round Trip
HTTP Request
HTTP Response
Codebehind
Source
.aspx
Create
Page Object
Page Class IL
JIT Compiler
Populate
Members
Page Object
Fire
Events
Render
HTML
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
41
Page Processing
Page/Control events get executed on
the server during page processing
First, the Page.Load event for
requested page
Followed by:


Other page events
Other “cached” control events
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
42
Control Events
Posted form parameters indicate:


Which control initiated HTTP POST
Selected control values
ASP.NET determines which events to
fire


Based on changes in control values
Based on initiator of POST
Some controls can trigger a POST

Button click, Textbox change, Listbox select
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
43
HTTP POST: Button Click
Example:



Enter a new TextBox value
Select from a DropDownList or ListBox
Click a Button
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
44
HTTP POST: Button Click
POST /ASPNETVB/ViewState/WebForm1.aspx HTTP/1.1
Cache-Control: no-cache
Connection: Keep-Alive
Content-Length: 135
Content-Type: application/x-www-form-urlencoded
Accept: ...; Accept-Encoding: gzip, deflate
Accept-Language: en-us
Cookie: .ASPXAUTH=...;
ASP.NET_SessionId=ns53k155dbrbid21tccazt2e
Host: localhost
Referer: http://localhost/ASPNETVB/ViewState/WebForm1.aspx
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR
1.0.3705)
__VIEWSTATE=dDwxMTIxMTQ1NzU1Ozs%2BAXQdcFai%2F004j3lupIyx0ltGA4U%3D&TextBo
x1=goodbye&Button1=Select&DropDownList1=Item+4&ListBox1=Item+3
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
45
HTTP POST: Button Click
Form parameters indicate user
entries:




TextBox1=goodbye
Button1=Select
DropDownList1=Item 4
ListBox1=Item 3
__VIEWSTATE=dDwxMTIxMTQ1NzU1Ozs%2BAXQdcFai%2F004j3lupIyx0ltGA4U%3D&TextBo
x1=goodbye&Button1=Select&DropDownList1=Item+4&ListBox1=Item+3
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
46
Accessing Form Parameters
Page members are recreated on the
round-trip

If view state is enabled
Control names in codebehind match
.aspx identifiers
// Control Members
protected System.Web.UI.WebControls.TextBox TextBox1;
protected System.Web.UI.WebControls.DropDownList DropDownList1;
// Code to access member values
s = TextBox1.Text;
s = DropDownList1.SelectedItem.Text;
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
47
Accessing Form Parameters
Request.Form property contains
name/value pairs

Regardless of view state
s = Request.Form[“TextBox1”];
s = Request.Form[“DropDownList1”];
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
48
HTML Output
 ASP.NET generates HTML output

Automatic management of browser output
 Hidden <input>

__VIEWSTATE field stores persisted page and
control data between round trips
<body MS_POSITIONING="FlowLayout">
<form name="Form1" method="post" action="WebForm1.aspx" id="Form1">
<input type="hidden" name="__VIEWSTATE"
value="dDwxNDI1MDc1NTU1Ozs+BikBQY0EO1e4Kf6Hy4QBNSYWNZM=" />
....
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
49
HTML Output
 Client Script
Emitted with HTML output as client-side script
block
 ASP.NET validation controls emit client script

<body MS_POSITIONING="FlowLayout">
<form name="Form1" method="post" action="WebForm1.aspx"
language="javascript" onsubmit="ValidatorOnSubmit();" id="Form1">
<input type="hidden" name="__VIEWSTATE"
value="dDwxNDI1MDc1NTU1Ozs+BikBQY0EO1e4Kf6Hy4QBNSYWNZM=" />
<script language="javascript"
src="/aspnet_client/system_web/1_0_3705_288/WebUIValidation.js"></script>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
50
Part I: Fundamentals
My First ASP.NET Application
Page Processing & HTML Output
ASP.NET Server Controls
State Management
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
51
HTML vs. Server Controls
HTML Controls



Follow DHTML object model
Fewer Properties, Methods, Events
Valuable when no server interaction, or client
side events are also necessary
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
52
HTML vs. Server Controls
ASP.NET Server Controls

Similar to Windows Forms object model
More functionality:

DataGrid, DataList, Calendar
Different syntax


Requires JIT compilation
First page load is affected
Are always run on the server

Round trips can be managed
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
53
WebControls Namespace
 System.Web.UI.WebControls

Contains classes for creating Web server controls
 Base Class WebControl


Contains common members for all Web server controls
BackColor, ForeColor, Font, Height, Width etc.
 Web server controls render their own HTML


Page class is the container for controls
Controls render their own HTML as Page is rendered
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
54
Web Server Controls
 Some Shared Properties:
AutoPostBack – should events be posted or
cached?
 EnableViewState – property persistence
 CssClass – style sheet class
 Tooltip – “title” attribute of HTML element
 Visible/Enabled

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
55
Button
 Can be a submit button or command
button
 Default is submit button

Handle the Click event
 Set CommandName, CommandArgument
property



Handle Click or Command event
Both events are fired on submit
Command event receives CommandEventArgs
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
56
ImageButton, Image
 ImageButton is similar to Button
Handle Click or Command events
 Displays an image
 Properties: ImageAlign, ImageUrl,
AlternateText

 Image displays an image
No postback events
 Properties: ImageAlign, ImageUrl,
AlternateText

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
57
LinkButton, HyperLink
 LinkButton creates a hyperlink with
Button functionality

Handle Click or Command events
 HyperLink creates a hyperlink
Link directly to another page, no postback
 Can display text or image
 Properties: Text, ImageUrl, NavigateUrl,
Target

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
58
TextBox
 TextMode Property

SingleLine, MultiLine, Password
 TextChanged Event
Triggers server post if the AutoPostBack
property is true
 Otherwise, event is cached until post occurs
 Event will still be triggered, not guaranteed in
what order compared to other control server
events

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
59
List Controls
Similar to Windows Forms controls
Support Data Binding (covered later)
Base Class WebControls.ListControl




DropDownList
ListBox
CheckBoxList
RadioButtonList
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
60
Validation Controls
 Validation controls inherit BaseValidator


Which inherits Label
Which inherits WebControl
 Validate associated input control

Can apply multiple validation controls to a single
control
 Support client-side validation


Deliver JavaScript to the client (no coding necessary!)
Avoid round trip for validation
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
61
Validation Controls
Place control on the form where error
messages should appear
Error message will be displayed if
validation fails
Can be validated on client or server
(defaults to client validation)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
62
Validation Controls
Text appears if validation fails
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
63
Validation Controls







RequiredFieldValidator
RangeValidator
RegularExpressionValidator
CustomValidator
CompareValidator
ValidationSummary
Can create custom validation controls

Inherit BaseValidator
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
64
Common Properties
 ControlToValidate – which input control
to validate
 EnableClientScript – controls
client/server validation
 ErrorMessage – message to display in
ValidationSummary control or in this
control
 Text – overrides display in this control,
use * if using ValidationSummary control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
65
RequiredFieldValidator
Validates the specified control for
user input
Compares input value to IntialValue
property
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
66
RangeValidator
 Specify a data type to compare
 Specify a maximum and minimum
 Validation succeeds if
input data is empty
 Use
RequiredFieldValidator
to enforce value
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
67
RegularExpressionValidator
Matches input against a pattern

E-mail, Phone Numbers, SSN
Set ValidationExpression property


Dialog box supports predefined choices
Can create custom expression
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
68
RegularExpressionValidator
Client validation uses JScript
Server uses RegEx
Validation succeeds if input
data is empty
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
69
CompareValidator
 Compare the validated control input value
with another control’s input value

ControlToValidate, ControlToCompare properties
 Compare to a static value

ValueToCompare, Type properties
 Use Operator property to
indicate method of
comparison


Measure equality
Perform data type checks
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
70
CustomValidator
User-defined validation for input
For client validation specify
ClientValidationFunction
For server validation,
handle ServerValidate
event
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
71
ValidationSummary
ErrorMessage property values will be
listed in summary control
Text property displays in control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
72
Server-Side Validation
Server validation always performed
Page.Validate initiates validation
By default, validation happens after
Page.Load event, before individual
control events

Invoked by ASP.NET
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
73
Server-Side Validation
Page.Validate method must be
explicitly called prior to checking
Page.IsValid property during
Page.Load
Can override failed validation by
correcting problem and re-validating
(call Page.Validate)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
74
Part I: Fundamentals
My First ASP.NET Application
Page Processing & HTML Output
ASP.NET Server Controls
State Management
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
75
State Management
Application State


Data for an entire application
Limited use for frequently used, static data
Session State


Isolates data for a specific user
Default session timeout is 20 minutes, can be
configured
View State

Persistence of page and control properties
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
76
HttpApplicationState
Exposed through intrinsic Application
object



HttpApplication.Application
HttpContext.Application
Page.Application
Stores Key/Value Pairs


Add any type of object to the collection
Access using standard collection syntax, by
name or index value
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
77
Application Values
HttpApplication.StaticObjects
Collection

Stores object with application scope created
using the <object> tag
// setting values
Application.Add(“dbconnect", "Provider=SQLOLEDB.1;…”);
or
Application[“dbconnect”] = "Provider=SQLOLEDB.1;…”;
// getting values
String s = (String)Application[“dbconnect"];
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
78
Application StaticObjects
Generate object with scope via
global.asax
Instantiated when application is
started
Access via
Application.StaticObjects
Use Lock(), UnLock() to protect
state
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
79
Application StaticObjects
// in global.asax
<object id=“appobj" scope="application"
class="StateManagement.UrlInfo" runat="server"/>
// setting value when application is loaded
Application.Lock();
UrlInfo obj = (UrlInfo)Application.StaticObjects[“appobj"];
obj.Url="http://www.idesign.net";
obj.Title="IDesign Associates";
Application.UnLock();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
80
HttpApplicationState
 Limitations
Application state information is cleared when
application is restarted
 Not shared across multiple servers (web
farms)
 Uses memory resources
 Only thread safe objects should be saved
 Locking can cause scalability issues

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
81
HttpSessionState
Exposed through intrinsic Session
object



HttpApplication.Session
HttpContext.Session
Page.Session
Stores Key/Value Pairs


Add any type of object to the collection
Access using standard collection syntax, by
name or index value
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
82
Session Values
HttpSessionState.StaticObjects
Collection

Stores object with session scope created
using the <object> tag
// setting values
Application.Session.Add(“name",”Joe Smith”);
or
Application.Session[“name“] = ”Joe Smith”;
// getting values
String s = (String)Application.Session[“name"];
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
83
Session StaticObjects
Generate object with scope via
global.asax
Instantiated when each session is
started

One object for each active session
Access via Session.StaticObjects
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
84
Session StaticObjects
// in global.asax
<object id=“sessionobj" scope="application"
class="StateManagement.UrlInfo" runat="server"/>
// setting value when application is loaded
UrlInfo obj =
(UrlInfo)Application.Session.StaticObjects[“sessionobj"];
obj.Url="http://www.idesign.net";
obj.Title="IDesign Associates";
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
85
Session Configuration
Machine.config


By default enables session state
Can override in Web.config
EnableSessionState


Attribute of the @ Page directive
Set to False for pages that don’t require a
session object


Delays creation of session object
Can’t use Session object from pages that
have this disabled
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
86
ViewState
 Used to persist ASP.NET server
control state between round trips
 Implemented with a hidden field in
client HTML
 Can be disabled per page or control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
87
ViewState
EnableViewState=true
<%@ Page EnableViewState=“True” … %>
<input type="hidden" name="__VIEWSTATE"
value="dDwyMTIzNzU4NjczO3Q8O2w8aTwxPjs+O2w8dDw7bDxpPDM+Oz47bDx0PHQ8O3A8bD
xpPDA+O2k8MT47aTwyPjs+O2w8cDxDb2xvciBbQWxpY2VCbHVlXTtDb2xvciBbQWxpY2VCbHV
lXT47cDxDb2xvciBbQXF1YV07Q29sb3IgW0FxdWFdPjtwPENvbG9yIFtBcXVhbWFyaW5lXTtD
b2xvciBbQXF1YW1hcmluZV0+Oz4+Oz47Oz47Pj47Pj47PkZfIFK00pyBR1IaAbVIeLcMIvyz"
/>
EnableViewState=false
<%@ Page EnableViewState=“False” … %>
<input type="hidden" name="__VIEWSTATE"
value="dDwyMTIzNzU4NjczOzs+e1hHXUI/yYEBrzVT8KuMABh8T7A=" />
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
88
ViewState
You can save custom state
information from page to page using
ViewState
// setting values
this.ViewState[“customerid"] = “12345";
// getting values
String s = (String)ViewState[“customerid"];
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
89
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
90
ADO.NET Data Providers
Set of classes interacting with a
specific type of datasource

Optimized access
Provided with .NET


SQL Server Provider
OLE DB Provider
Other providers can be downloaded
from Microsoft

I.e., .NET Data Provider for Oracle
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
91
Data Provider Objects
 ADO.NET Classes supporting
interaction with database providers
 Categories of classes:
Connection
 Command
 DataReader
 DataSet
 DataAdapter
 DataView

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
92
Data Access – Basic Steps
 Create and Open Connection
 Create Command object with SQL query
statements or Stored Procedure name
 Execute command and retrieve data
 Manually iterate through dataset results
OR
 Bind dataset results directly to Web
controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
93
Connection Object
 OleDbConnecton or SqlConnection

Implements IDbConnection
 Establish and terminate data source
connection
 Properties initialized by constructor



ConnectionString
Database
DataSource
 Must be explicitly closed

Call Close() or Dispose()
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
94
Connection Object
SqlConnection objSQLConnection = new SqlConnection("Data Source=.;
Initial Catalog=pubs; UID=sa; PWD=");
objSQLConnection.Open();
// do work
objSQLConnection.Close()
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
95
Connection String Examples
 Connection string is database-specific
 SQL Server Example:
"Data Source=.; Initial Catalog=pubs; UID=sa; PWD="
"server=localhost; database=pubs; uid=sa”
 Microsoft Access (*.mdb) Example:
“PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA Source=[path]authors.mdb”
 DSN Example:
“DSN=myDSN”
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
96
Command Object
OleDbCommand or SqlCommand

Implements IDbCommand
Execute SQL statements or Stored
Procedures against datasource
Requires a valid Connection be
opened prior to execution

Connection property
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
97
Command Object
 Commands are executed to return data




ExecuteNonQuery()
ExecuteReader()
ExecuteScalar()
ExecuteXmlReader() – SqlCommand only
 CommandType indicates how command
should execute against an open
connection
 SQL query is default setting
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
98
ExecuteReader()
Returns IDbReader object


SqlCommand returns SqlDataReader
OleDbCommand returns OleDbDataReader
SqlCommand objSQLCommand;
string strSQL = "select * from authors";
objSQLCommand = new SqlCommand(strSQL, objSQLConnection);
SqlDataReader reader = objSQLCommand.ExecuteReader();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
99
Sample SQL Queries
SELECT list of fields FROM table name
SELECT * FROM Titles
SELECT Title, [Year Published], ISBN FROM Titles
SELECT Titles.Title, Titles.[Year Published], Titles.ISBN,
Publishers.Name FROM Titles
SELECT list of fields FROM table name WHERE condition
SELECT * FROM Titles WHERE [Title] = ‘some title’
SELECT * FROM Titles WHERE [Year Published] > 1990
SELECT list of fields FROM table name WHERE condition ORDER BY field
SELECT * FROM Titles WHERE [Year Published] = 1990 ORDER BY Title
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
100
DataReader Object
OleDbDataReader or SqlDataReader

Implements IDbReader
Read-only and forward-only access
to a set of rows from the datasource
Lightweight, high-performance
access
Reads only 1 record at a time
Cannot be cached on the server
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
101
DataReader Object
Iterating through a DataReader
SqlDataReader reader = objSQLCommand.ExecuteReader();
while (reader.Read()) {
// Example: get values from the first field
string s = (string)reader.GetValue(0);
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
102
DataReader Object
Assigning a DataReader to the
DataGrid.DataSource
SqlDataReader reader = objSQLCommand.ExecuteReader();
dagMain.DataSource = reader;
dagMain.DataBind();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
103
DataSet Object
 In-memory representation of XML or
datasource

Disconnected, remotable
 Not tied to a provider
 Manipulation of
relational data
 Tables, Rows,
Columns, Constraints,
Relationships
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
104
DataSet Object
System.Data.DataSet ds = new System.Data.DataSet();
SqlDataAdapter da = new SqlDataAdapter(objSQLCommand);
int n = da.Fill(ds);
foreach (DataTable tbl in ds.Tables) {
foreach (DataRow tr in tbl.Rows) {
foreach (object o in tr.ItemArray)
// access to fields
}
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
105
DataAdapter Object
 OleDbDataAdapter or SqlDataAdapter


Implements IDbDataAdapter
IDbDataAdapter inherits IDataAdapter
 Bridge between DataSet and data source
 Can update the data source using
specified SQL commands
 Can generates a DataSet or DataTable

Use Fill() method from prior examples
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
106
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
107
Core Databound Controls
ListControl (Base)




DropDownList
ListBox
CheckBoxList
RadioButtonList
DataGrid
DataList
Repeater
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
108
Common Binding Properties
 DataSource – source of data binding
 DataValueField – field from data source
that provides the value of each item
 DataTextField – field from data source to
display
 DataMember – indicates a member from
a multi-member DataSource (i.e., multiple
tables in a DataSet)
 DataTextFormatString – format string
to be used on data bound to the control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
109
Bound List Controls
Bind to an array
Specify DataSource
Issue DataBind() for the control or
page
string[] colors =
System.Enum.GetNames(typeof(System.Drawing.KnownColor));
this.ListBox1.DataSource=colors;
this.DataBind();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
110
Bound List Controls
Bind to an XML file
Specify DataSource, DataTextField,
and DataValueField (optional)
Issue DataBind() for control or page
System.Data.DataSet ds = new DataSet("cultures");
string sPath = this.MapPath("");
StringBuilder sb = new StringBuilder();
sb.AppendFormat("{0}\\cultures.xml", sPath);
ds.ReadXml(sb.ToString());
lstCultures.DataSource=ds;
lstCultures.DataValueField = "value";
lstCultures.DataTextField = "descrip";
lstCultures.DataBind();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
111
Bound List Controls
Bind to a particular column
Specify DataSource, DataTextField,
and DataValueField (optional)
Issue DataBind() for control or page
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
112
Bound List Controls
SqlConnection objSQLConnection = new
SqlConnection("Data Source=.; Initial Catalog=pubs; UID=sa; PWD=");
SqlCommand objSQLCommand;
string strSQL = "select * from authors";
objSQLConnection.Open();
objSQLCommand = new SqlCommand(strSQL, objSQLConnection);
System.Data.DataSet ds = new System.Data.DataSet();
SqlDataAdapter da = new SqlDataAdapter(objSQLCommand);
int n = da.Fill(ds);
ddl.DataSource=ds;
ddl.DataTextField="au_fname";
ddl.DataValueField="au_fname";
ddl.DataBind();
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
113
DataGrid Control
 Bind to a data source
 Specify DataSource
 Issue DataBind() for the control or page
System.Data.DataSet ds = new DataSet("cultures");
string sPath = this.MapPath("");
StringBuilder sb = new StringBuilder();
sb.AppendFormat("{0}\\cultures.xml", sPath);
ds.ReadXml(sb.ToString());
this.DataGrid1.DataSource=ds;
this.DataGrid1.DataBind();
 AutoGenerateColumns is true by default
 Set to false if specifying columns to bind
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
114
DataGrid Appearance
Header and Footer


FooterStyle, ShowFooter
HeaderStyle, ShowHeader
Row Appearance



ItemStyle
SelectedItemStyle
AlternatingItemStyle
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
115
DataGrid Paging
AllowPaging

Enables paging, disabled by default
PageSize defaults to 10
PagerStyle

Set properties of the paging area
Custom paging also supported


Optimize process for large datasets
Greater control over paging process
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
116
DataGrid Paging
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
117
DataGrid Paging
 PageIndexChanged Event


Handle this to complete implementation for paging
DataGridPageChangedEventArgs provides access to
selected page index
private void dagMain_PageIndexChanged(object source,
System.Web.UI.WebControls.DataGridPageChangedEventArgs e)
{
dagMain.CurrentPageIndex = e.NewPageIndex ;
dagMain.DataBind();
}
 Bound data is lost on round-trip

Must rebind data source after setting the page index
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
118
DataGrid Columns
Can indicate specific columns and
fields to bind to
Can format, sort,
alter column header
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
119
DataGrid Columns
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
120
DataGrid Commands
Can add button columns for
selection, edit/update/cancel, or
delete
Should handle events for each button
action
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
121
DataGrid Commands
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
122
DataGrid Commands
Events provided for each command:

CancelCommand, DeleteCommand,
EditCommand, UpdateCommand,
SelectIndexCommand
private void OnSelectedIndexChanged(object sender,
System.EventArgs e)
{
// SelectedItem has been set when this event is triggered
TableCellCollection cells = DataGrid1.SelectedItem.Cells;
Response.Write(String.Format(“Selected row contains:{0},{1},{2}<br>“,
cells[0].Text, cells[1].Text, cells[2].Text));
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
123
DataGrid Commands
ItemCommand Event is invoked for
all commands
Invoked prior to individual
commands
Can check command name using
static members
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
124
DataGrid Commands
private void OnItemCommand(object source,
System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
if (e.CommandName == DataGrid.SelectCommandName)
{
// Cell information is available from the
// DataGridCommandEventArgs
string s = e.Item.Cells[0].Text;
// at this time, selectedIndex is -1,
// so if accessing the SelectedItem
// in this handler, must set SelectedIndex first
DataGrid1.SelectedIndex = e.Item.ItemIndex;
s = DataGrid1.SelectedItem.Cells[0].Text;
// s holds productId
}
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
125
DataList Control
 Initialize similar to DataGrid


Set DataSource and issue DataBind() command
Handle command events
 Must define templates for rows and
columns



Using VS.NET editor
Using HTML directly
Programmatically
 Does not support automatic paging or
sorting

Use DataGrid for these features
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
126
Editing DataList Templates
VS.NET design environment supports
editing
templates for
header, footer,
items and
separators
Right-click on
control and
select from
Edit Template
menu options
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
127
Templates
Draw HTML or ASP.NET controls from
the ToolBox into template regions
Can edit style such as background
color and font
Header and
Footer
Templates
Regular Item
Template
Alternating Item
with different
background color
Separator
Template
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
Edit Item with TextBox in
place of Labels
128
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
129
Binding Data
Bind elements of each row using
DataBindings dialog

Accessible from the Properties window
Alternative to editing HTML directly
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
130
Binding Data
List of
bindable
properties
Custom binding
expression
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
131
Binding Data
Bind control to data source
OleDbDataReader rdr = cmd.ExecuteReader();
this.DataList1.DataSource = rdr;
this.DataList1.DataBind();
Data bindings added to HTML view
via DataBindings dialog, or manually
<FooterTemplate>
Last Updated: <asp:Label id="labLastUpdated" runat="server"
BackColor="Transparent"><%# DateTime.Now %></asp:Label>
</FooterTemplate>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
132
Binding Data
Example binding to specific fields in
the data source
DataSource property must be set
before DataBind() issued, and field
names must be correct
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
133
Binding Data
<ItemTemplate><TABLE>
<TR><TD><asp:Label id=labProductName runat="server"
Text='<%# DataBinder.Eval(Container.DataItem, "productName") %>'>
</asp:Label><BR>
<asp:Label id=labFilename runat="server"
Text='<%# DataBinder.Eval(Container.DataItem, "thumbNailImage") %>'>
</asp:Label></TD>
<TD align="right">
<asp:Image id=img runat="server" ImageAlign="Right"
ImageUrl='<%# DataBinder.Eval(Container.DataItem,
"thumbNailImage","images/{0}") %>'>
</asp:Image></TD>
</TR></TABLE>
</ItemTemplate>
<SeparatorTemplate><HR width="100%" color="#6633ff"
SIZE="1"></SeparatorTemplate>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
134
DataList Appearance
Can arrange HTML
output per row
Further customizable
using DataRepeater
control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
135
Data Binding
 Process of tying UI elements to a
datastore such as a DataSet
 ASP.NET provides server-side data
binding
Removes issues of browser compatibility
 Binds and renders data on the server
 Outputs browser-independent HTML

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
136
DataSource Binding
Most ASP.NET server controls
support data binding
Properties Window
Set DataBindings for control
 Provides a list of properties
that are bindable for the
selected control

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
137
DataBind() Method
 Page.DataBind()


Can perform data binding at the page level
Binds all controls on the page
 Control.DataBind()

Instance method binds only that control
 Binding forces the evaluation of databinding expressions
 Renders values to HTML output
 DataBinding() event is triggered when
binding occurs for the page
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
138
Data Binding Expressions
Placed between <%# … %>
<tagprefix:tagname property="<%# data-binding expression %> runat="server" />
or
literal text <%# data-binding expression %>
Used to bind control properties
<asp:Label runat="server" Width="212px">
<%# ListBox1.SelectedItem.Text %>
</asp:Label>
Used anywhere in the page
<%# m_SomeValue %>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
139
DataBinder.Eval
Evaluates and formats the result of
late-bound data-binding expressions
Uses late-binding and reflection
Carries overhead, but assists with
data type casting
Can be useful for single-line
formatting
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
140
DataBinder.Eval
Convert “Amount” field to string:
<%# DataBinder.Eval(Container.DataItem, “Amount”) %>
Format “thumbNailImage” field with
path:
<asp:Image id=img runat="server" ImageAlign="Right"
ImageUrl='<%# DataBinder.Eval(Container.DataItem,
"thumbNailImage","images/{0}") %>'>
</asp:Image></TD>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
141
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
142
Web User Controls
Reusable Web form interface

Only within the same project
Designed just like Web forms


Drag & drop Web controls, write event
handlers, etc.
Unlike custom Web server controls (covered
later)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
143
Creating Web User Controls
Add a Web User Control to the
project
*.ascx file is added to project
Design as you would a Web page
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
144
Using Web User Controls
From Solution Explorer, drag & drop
the .ascx file to an open Web form
Adds @ Register to HTML

Source file, tag prefix & tag name
<%@ Register TagPrefix="uc1" TagName="Login" Src="Login.ascx" %>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
145
Using Web User Controls
Adds control declaration to HTML

Must be contained within <form> tag for
events to work!
<form id="Form1" method="post" runat="server">
<uc1:Login id="ucLogin" runat="server"></uc1:Login>
</form>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
146
Web User Controls Features
Compiled dynamically at runtime

Can’t be added to the Toolbox
Supports properties!

No Properties Window support
Easy to design using HTML Designer
Can combine Web user controls from
multiple languages on a page
Support for fragment caching
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
147
Fragment Caching
Web User Controls can be cached
@ OutputCache Directive

Placed inside *.ascx file
<%@ OutputCache Duration="30" VaryByParam="none" %>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
148
Fragment Caching
PartialCachingAttribute


Placed in codebehind file, as an attribute to
the Web user control class
Attribute constructor supports supplying only
Duration value
[PartialCaching(30)]
public abstract class Login : System.Web.UI.UserControl
{
// control definition
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
149
Part II: Advanced Techniques
Crash Course in ADO.NET
ASP.NET Database Server Controls
DataBinding
Web User Controls
Custom Web Server Controls
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
150
Custom Web Server Controls
Great for code re-use, maintenance
and specialization
Assembly deployment model




Completely reusable binary component
Can leverage .NET versioning
Single copy shared by multiple projects
Can be deployed to the Global Assembly
Cache (GAC)
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
151
Web Control Library
New Web Control Library project
Project generates one Web control
class by default, can define more
classes
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
152
Web Control Base Classes
System.Web.UI.Control

Base class to Page object & all Web server
controls (some through WebControl)
Properties Provided



ID
EnableViewState
Visible
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
153
Web Control Base Classes
 System.Web.UI.WebControls.WebControl
 Derived from Control
 Base class to Web server
controls
 Default base class for a
new Web Control Library
 Properties Provided

BackColor, BorderStyle,
CssClass, Enabled, Font,
Visible, Width
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
154
HtmlTextWriter
 Render method provides access to the
HtmlTextWriter
 Provides methods to write HTML tags and
content to the output stream


AddAttribute, RenderBeginTag, RenderEndTag
Write, WriteLine
 Static constants

SelfClosingEndTag, SingleQuoteChar,
SpaceChar
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
155
HtmlTextWriter
HtmlTextWriter rendering code:
protected override void Render(HtmlTextWriter output)
{
output.AddAttribute(HtmlTextWriterAttribute.Alt, “Flower Image”,
true);
output.AddAttribute(HtmlTextWriterAttribute.Src, “flower.jpg”
,
true);
output.AddAttribute("myattribute", “custom attribute info”, false);
output.RenderBeginTag(HtmlTextWriterTag.Img);
output.RenderEndTag();
output.WriteLine();
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
156
HtmlTextWriter
Resulting HTML output:
<img alt=“Flower Image" src=“flower.jpg” myattribute=“custom attribute
info” />
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
157
Render Method
Provides access to the
HtmlTextWriter to send output to the
Web form

Provides methods to write HTML tags and
content to the output stream
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
158
Render Method
protected override void Render(HtmlTextWriter output)
{
output.AddAttribute(HtmlTextWriterAttribute.Alt, "Encoding,
\"Required\"", true);
output.AddAttribute(HtmlTextWriterAttribute.Src,
“http://localhost//ASPNETCS//MLBWebControlClient//peaches_sm.jpg”
, true);
output.AddAttribute("myattribute", "No &quot;encoding &quot;
required", false);
output.RenderBeginTag(HtmlTextWriterTag.Img);
output.RenderEndTag();
output.WriteLine();
}
<img alt="Encoding, &quot;Required&quot;"
src="http://localhost//ASPNETCS//MLBWebControlClient//peaches_sm.jpg"
myattribute="No &quot;encoding &quot; required" />
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
159
Using Web Server Controls
 From the Tools menu, select Customize
Toolbox…
 Browser for your Web server control DLL

Select the control, it will be added to the toolbox
 Drag & drop the control to the Web form
 Adds @ Register to HTML

Source file, tag prefix & tag name
<%@ Register TagPrefix="cc1" Namespace="OrderImage" Assembly="OrderImage"
%>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
160
Using Web Server Controls
Adds control declaration to HTML
<form id="Form1" method="post" runat="server">
<cc1:WebCustomControl1 id="WebCustomControl11"
runat="server"></cc1:WebCustomControl1>
</form>
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
161
Composite Controls
Implement INamingContainer


No methods or properties
Ensures unique namespace for child controls
in Page hierarchy
Override
Control.CreateChildControls()


Add child controls to Controls collection
Creates a composite control
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
162
Composite Controls
Add to the Controls collection of the
WebControl or Control class
Create Web server controls, set their
properties, including style and
position
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
163
Composite Controls
Create HTML literals, also added to
Controls collection
protected override void CreateChildControls()
{
this.Controls.Add(new LiteralControl("<center>"));
Label label1 = new Label();
label1.Text = "Click the button below.";
this.Controls.Add(label1);
this.Controls.Add(new LiteralControl("</center>"));
this.Controls.Add(new LiteralControl("<br>"));
Button btn = new Button();
btn.Text = "Click Me";
btn.Width=new Unit("50%");
btn.Click += new EventHandler(this.OnClick);
this.Controls.Add(btn);
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
164
Composite Controls
Overriding Control.Render()

For composite controls, call base class
Render()

Child controls will render themselves
Add custom rendering code if desired

protected override void Render(HtmlTextWriter output)
{
// do nothing, allow rendering by composite controls
base.Render(output);
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
165
Presentation Details
Library & Control Name

Displayed in Customize Toolbox dialog
Custom Icon

System.Drawing.ToolboxBitmapAttribute

Applied to the control class
Specify filename or resource item

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
166
Presentation Details
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
167
Presentation Details
[ToolboxBitmap("toolbox.ico")]
[DefaultProperty(“Description"),
ToolboxData("<{0}:ImageInfo runat=server></{0}:ImageInfo>")]
public class ImageInfo : System.Web.UI.WebControls.WebControl,
INamingContainer
{
// Control definition
}
Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
168
References
.NET Dashboard

http://www.dotnetdashboard.net

A growing list of articles and code
Web Services Tutorial Site

http://www.dotnetdashboard.net/ark/aspnettutorial.aspx

Tutorial session code samples
Additional references

Copyright 2000-2003 Michele Leroux Bustamante. All rights reserved.
169