Web User Controls

1
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
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About Your Speaker

• Name Joseph White - JoeCasa1_at_Yahoo.com
• 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.

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Web User Controls

• First, Lets resolve the name ambiguity
• User Controls
• Could be confused with windows forms controls.
• Server Controls
• Not ambiguous if you know what you are talking
  about.
• Custom Controls
• Just as confusing as user controls.
• Web Controls
• Used interchangeably to reference either web user
  controls or server controls.

4
Web User Controls

• What they are
• 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.

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Web User Controls

• What they are NOT
• They aint server controls.
• Easily distributed or shared across multiple web
  projects.
• Something you would want to package and sell to
  the public.

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Web User Controls

• Why not just use an old fashion include?
• Include files are not encapsulated objects.
• 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?
• Too much work.

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Web User Controls

• Lets take a peek at what they look like in
  Visual Studio

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Web User Controls

• Two part entry into the aspx page.
• Part 1 The declaration.
• lt_at_ Register TagPrefix"uc1" TagName"PageHeader"
  Src_PageHeader.ascx" gt
• 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 Lets the page know where it can find the
  ascx file that goes with the control.

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Web User Controls

• Part 2 The actual control tag.
• ltuc1pageheader id"_PageHeader1" runat"server"
  /gt

Required if manipulating on Server
TagName
TagPrefix
Unique instance identifier
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Lets Make a Simple Control
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Web User Controls

• Things to Note
• The control does not declare itself in the code
  behind.
• Use Page.FindControl.
• Manually type in the declaration.
• The properties do not show up in the property
  sheet.
• The design view can be drastically different from
  the runtime view.
• In fact, when placed in a repeater control, they
  become invisible in the designer.
• A web user control can host another web user
  control.

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ASP.NET Validation ControlsSpecial 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.
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Web User Controls

• Using Validators in a web user control
• 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.

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Web User Controls

• Complex regular expression
• (0?1-910-2)/(0-2?0-930-1)/((12)\d3
  \d2) (0-10-920-3)0-50-9
• 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.

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Validation Controls Demo
http//www.ilmservice.com
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Web User Controls

• Working with style sheets.
• Style Sheet Advantage
• Since the controls are site specific you dont
  have to worry about all sorts of properties to
  handle styles.
• Style Sheet Disadvantage
• Since the style sheet is declared at the page
  level, your control (ascx file) may not look
  quite right in the VS designer.

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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.
• Use Page.RegisterClientScriptBlock and
  Page.IsClientScriptBlockRegistered

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Web User Controls

• Conclusions
• Pros
• Easy to create
• Same programming model as ASP.NET Page
• 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.

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Web User Controls

• Conclusions
• Cons
• Doesnt play well with the VS designer.
• 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.
• Cant package and sell as a stand alone DLL.

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Web User Controls

• Thank you for your attention.