Transcript Web User Controls with Standard Validators

Web User Controls
This presentation will cover the basics of defining,
creating and using a web user control.
Presented to Twin Cities .NET user group
By Joseph White
Chief Architect, Eden Systems International
http://www.EdenSI.com
August 5th, 2004
About Your Speaker
• Name: Joseph White - [email protected]
• Occupations:
– Chief Software Architect for Eden Systems International
– .NET mentor and architect (part time contracting available through
ILM, your .NET solution provider)
– Self Proclaimed “Lazy Programmer”
• Experience:
– Working with .NET for over 3 years, developing software
solutions, teaching and mentoring for over a decade.
Web User Controls
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First, Let’s resolve the name ambiguity
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User Controls
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Server Controls
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Not ambiguous if you know what you are talking about.
Custom Controls
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Could be confused with windows forms controls.
Just as confusing as user controls.
Web Controls
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Used interchangeably to reference either web user controls
or server controls.
Web User Controls
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What they are:
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Similar in functionality to ASP include files but much
better.
Encapsulate HTML and code into smaller functional
units.
Built similar to web forms but hosted on a page as an
object.
Reusable within the web project that hosts them.
Web User Controls
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What they are NOT
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They ain’t server controls.
Easily distributed or shared across multiple web
projects.
Something you would want to package and sell to the
public.
Web User Controls
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Why not just use an old fashion include?
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Include files are not encapsulated objects.
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Potential variable name conflict with host web page or other
instances of the “included” code.
Can not be programmatically manipulated by host page.
Web user controls contain properties and raise events which
provides fluid interaction between the control and the
hosting page.
Why not create a server control?
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Too much work.
Web User Controls
Let’s take a peek at what they look like
in Visual Studio
Web User Controls
Two part entry into the aspx page.
Part 1: The declaration.
<%@ Register TagPrefix="uc1" TagName="PageHeader" Src=“_PageHeader.ascx" %>
TagPrefix: This is like a namespace in case you want to include other controls with the same
name. Usually defaults to uc1.
TagName: Again its only significance is to help uniquely identify the control on the page.
Usually defaults to the name of the class.
Src: Let’s the page know where it can find the ascx file that goes with the control.
Web User Controls
Part 2: The actual control tag.
TagName
Required if manipulating on Server
<uc1:pageheader id="_PageHeader1" runat="server" />
TagPrefix
Unique instance identifier
Let’s Make a Simple Control
Web User Controls
Things to Note:
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The control does not declare itself in the code behind.
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The properties do not show up in the property sheet.
The design view can be drastically different from the
runtime view.
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Use Page.FindControl.
Manually type in the declaration.
In fact, when placed in a repeater control, they become invisible
in the designer.
A web user control can host another web user control.
ASP.NET Validation Controls
Special kind of server controls used for validating input
values entered in other server controls. A variety of validation
controls allow us to require input, check for formats, compare
with other fields, and perform custom operations.
Web User Controls
Using Validators in a web user control
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Encapsulate Complex Validation Logic
Validators in the user control will work with the
validation summary control on the page.
Because the web user control is web project
specific it is easy to give validators a consistent
look throughout the application.
Web User Controls
Complex regular expression:
(0?[1-9]|1[0-2])/([0-2]?[0-9]|3[0-1])/((1|2)\d{3}|\d{2}) ([01][0-9]|[2][0-3])[0-5][0-9]
Evaluates mm/dd/yy or mm/dd/yyyy with the leading 0 on the
month or day being optional.
Then it ends with HHMM where leading zero is not optional.
Validation Controls Demo
http://www.ilmservice.com
Web User Controls
Working with style sheets.
• Style Sheet Advantage:
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Since the controls are site specific you don’t have to
worry about all sorts of properties to handle styles.
Style Sheet Disadvantage:
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Since the style sheet is declared at the page level,
your control (ascx file) may not look quite right in the
VS designer.
Web User Controls
Working with client side script
• Best Practice for large script blocks is to use an
include file.
• Since a control may be included more than once
on a page, It is important to make sure the script
functions are only included once.
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Use Page.RegisterClientScriptBlock and
Page.IsClientScriptBlockRegistered
Web User Controls
Conclusions
Pros:
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Easy to create:
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Same programming model as ASP.NET Page
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Code Behind
Page Load event
Post Back events
Encapsulate complex expressions, functions and html
code.
OO approach avoids the pitfalls of copy and paste or old
fashion includes.
Web User Controls
Conclusions
Cons:
• Doesn’t play well with the VS designer.
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Renders as a gray box in design view.
Exposed properties not available in property sheet.
Does not declare itself in the code behind.
Difficult to share across multiple web projects.
Can’t package and sell as a stand alone DLL.
Web User Controls
Thank you for your attention.