ASP.NET Controls für Web Forms und MVC

1. Controls im Web
ASP.NET Controls für Web Forms und MVC
Daniel Fisher (lennybacon) | devcoach.com

2. Lennybacon.com
￭ Daniel Fisher | CTO & Software Architect
￭
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5. Agenda
• Web Controls
• What‘s MVC anyway?
• Recap 2006
• Controls for the Microsoft Web Platform
• Summary

7. 7
Is all about Maintainablility!
￭ The controls concept achieves reusability for
￭ Html mark-up
￭ Server-side code
￭ Client-side scripts
￭ Compiled code that can be reused in any
ASP.NET web application.

8. Controls in Code
public class MyControl
: Control
{
//…
}

9. Controls in Code: Usage
<asp:Contol
id="MyId"
runat="server"
/>

10. Web Form Pros

11. Web Form Cons
￭ No visual way of developing server controls,
generated via code.

12. What‘s MVC anyway?

13. Concepts
• Nice URLs & Routing
• Process over „just add a Form“
• Loads of naming conventions
• Code, Code, Code
• As strongly typed as possible!
• Once build, forever used…

14. Concepts cont.
• No Code-Behind for ASPXs
• No Postbacks
• No Viewstate
• And last but not least „No controls out of Redmond“!

16. Web Forms or MVC?

17. Once apon a time…

18. 18
Processing
￭ Child control creation
￭ CreateChildControls()
￭ All display logic
￭ OnPreRender()
￭ Rendering
￭ Custom: Render()
￭ Composite: Nothing to do?

19. PROBLEM #1: POSTBACKS

20. First Aid
￭ Response.Redirect(
http://example.org);
￭ Server.Transfer(
http://example.org);
￭ <a href=“…“>link</a>
￭ Server side only events
￭ AJAX

22. PROBLEM #2: VIEWSTATE

23. 23
Postback - Lifecycle of a control
Instantiate : Constructor
Initialize : OnInit method and Init Event
Begin Tracking View State : TrackViewState
Load View State : LoadViewState method
Load Postback Data : IPostBackDataHandler.LoadPostdata method
Load: OnLoad method and Load event
Raise Changed Events : IPostBackDataHandler.RaisePostDataChangedEvent method
Raise Postback Event : IPostBackEventHandler.RaisePostBackEvent method
PreRender : OnPreRender method and PreRender event
Save View State : SaveViewState method
Render : Render method
Unload : OnUnload method and Unload event
Dispose : Dispose Method

24. 24
ViewState
￭ ViewState is used to track and restore the state
values of controls that would otherwise be lost
￭ Base64 encoded - not easily readable, but not
encrypted!
￭ What to store
￭ Integers
￭ Strings
￭ Floats
￭ Decimals
￭ Arrays of the data types stated above

25. Viewstate in code
[Bindable(false)]
[Category("Appearance")]
[DefaultValue("This is the default text.")]
[Description("The text of the custom control.")]
public virtual string Text
{
get
{
var o = ViewState["Text"];
return o!=null
? (string) o
: "This is the default text.";
}
set { ViewState["Text"] = value; }
}

26. Viewstate in markup

27. First Aid
￭ Query Request.Form and
Request.QueryString
￭ Use local fields
￭ most times they work fine!

29. PROBLEM #3: BINDING

30. Binding in code
public overrride OnInit(
object sender, EventArgs e)
{
List<Person> persons =
Repository<Person>.GetAll();
myControl.DataSource = persons;
myControl.DataBind()
}

31. First Aid
￭ HttpContext.Current.Items
￭ Cast to ViewPage
￭ Access Model
￭ Cast to IEnumerable

33. PROBLEM #4: RESOURCES

34. Resources
￭ Images
￭ Java Script
￭ Styles

35. Resources in code
[assembly: WebResource(
"devcoach.Web.UI.Controls.Busy.gif",
"image/gif")]
imageUrl =
Page.ClientScript.GetWebResourceUrl(
GetType(),
"devcoach.Web.UI.Controls.Busy.gif");

36. First Aid
￭ Embedded
￭ VirtualPathProvider
￭ Routing