1. CS 3870/CS 5870
Web User Controls
Events (II)

2. Public Event Define event Raise event Handle event
Create Event Handler
Specify Event Handler

3. Test2
Event of User Control
Run my TestTwo locally

4. Test2 Event works when one item becomes invalid.
But may not work if multiple items are invalid.

5. Debugging
Break Points
Step Over
Continue
Stop

6. Dynamic Pages User request a dynamic page
Request a page (first time)
Post back
Revisit a page
ASP.NET generates the requested page
User receives a new page

7. Generating Dynamic Pages
Init
Load State
Process PostBack Data
Load
PostBack Events
Save State
Render
Unload

8. Generating Dynamic Pages with User Controls
Loading Page
Loading User Controls
Events triggered by loading user controls
PostBack Events

9. Other Items Could Be Invalid
Private Sub EventHandler(ByVal item As TestTwo_CourseAndCredit, ByVal valid As Boolean) If Not valid Then txtTotal.Text = "" Exit Sub End If For index = 0 To bag.Count - 1 c1 = bag.GetByIndex(index) If c1.CourseID = item.CourseID Then c1.Credits = item.Credits total += c1.Credits Next txtCredits.Text = total End Sub

10. CourseAndCredit.ascx
Partial Class TestTwo_CourseAndCredit Inherits System.Web.UI.UserControl ‘ Private data Private _courseID, _courseName As String ‘Private _credits As Integer Private _credits As String Private _valid As Boolean = True Private _message As String = “” End Class

11. User Control Load Event
Protected Sub TestTwo_CourseAndCredit_Load (. . .) Handles Me.Load txtID.Text = _courseID txtName.Text = _courseName txtCredits.Text = _credits lblMsg.Text = _message End Sub

12. Define Event Partial Class Prog7_ShoppingItem . . .
‘Public Event CreditsChanged(ByVal item As
‘ TestTwo_CourseAndCredit, ByVal valid As Boolean)
Public Event CreditsChanged(ByVal item As
TestTwo_CourseAndCredit)
End Class

13. Raise Event ‘ Update the object and raise event
Protected Sub txtCredits_TextChanged(…) Handles …
‘ update _valid
‘ update message
‘ update _credits
‘ display message
RaiseEvent CreditsChanged(Me)
End Sub

14. Raise Event Dim credits As Integer
If Integer.TryParse(txtCredits.Text, credits) Then
If credits <= 0 Then
_message = "Not positive"
_valid = False
ElseIf credits > 5 Then
_message = "Larger than 5"
Else
_message = ""
_valid = True
End If
_message = "Not an integer"
_credits = txtCredits.Text
lblMessage.Text = _message
RaiseEvent CreditsChanged(Me)

15. Add Event Handler
Protected Sub Page_Load(. . .) Handles Me.Load c1 = CType(LoadControl("../CourseAndCredit.ascx"), TestTwo_CourseAndCredit) AddHandler c1.CreditsChanged, AddressOf HandleChangeEvent theForm.Controls.Add(c1) End Sub

16. Private Sub HandleChangeEvent(ByVal Item
Private Sub HandleChangeEvent(ByVal Item ) Dim allValid as Boolean = True Dim total As Integer = 0 For i = 0 To bag.Count - 1 c = bag.GetByIndex(i) If c.theID = item.theID Then ‘ update the item in the bag End If If c.Valid Then total += c.theCredits Else allValid = False Next If allValid Then txtTotal.Text = total txtTotal.Text = “” End Sub

17. Web User Control Must Work Correctly At All Times!
Prog 6
Web User Control Must Work Correctly At All Times!

18. Session Variables Display the previously selected Course
Prog 6
Session Variables Display the previously selected Course

19. Prog 6
Copy Prog7 folder Paste as Prog6 folder Modify all files of Prog6 Make sure it works as Prog7 Then Work on Prog6!