VB.NET Event not Being Handled
Hello Experts,
I am just dipping into custom events and have hit a major snag. An event raised in one class is not being handled when another class initiates the sub that contains the event. I have attached my code. All help is greatly appreciated.
I am just dipping into custom events and have hit a major snag. An event raised in one class is not being handled when another class initiates the sub that contains the event. I have attached my code. All help is greatly appreciated.
Public Class ResultCollection
Inherits CollectionBase
Public Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
Default Public Overridable ReadOnly Property Item(ByVal index As Integer) As Result
Get
Return CType(Me.List(index), Result)
End Get
End Property
Public Sub Add(ByVal Result As Result)
List.Add(Result)
End Sub
Public Sub New()
End Sub
Public Sub New(ByVal CycleCountCompletionID As Integer)
Dim CurrCount As Integer = 0
Dim TotalRecords As Integer = 0
Dim SQL As String = [OMITTED]
Dim DS As DataSet = VSMS.GetDataSet(SQL, VSMS.TRIPConnStr)
TotalRecords = DS.Tables(0).Rows.Count
For Each DR As DataRow In DS.Tables(0).Rows
CurrCount += 1
Me.Add(New Result(Convert.ToInt32(DR.Item("CycleCountResultID"))))
RaiseEvent ResultLoaded(CurrCount, TotalRecords) '<-- EVENT FIRES HERE AND IS HANDLED PROPERLY IF I ADD AN EVENT HANDLER TO THE SAME CLASS
Next
End Sub
End Class
Public Class Completion
Private WithEvents _Results As New ResultCollection
Public Sub LoadResults()
_Results = New ResultCollection(CycleCountCompletionID) '<--This SHOULD get the event handler to start firing events.
End Sub
Public Sub _Results_ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer) Handles _Results.ResultLoaded
'EVENT SHOULD BE RAISED HERE, BUT DEBUGGING SHOWS THAT IT IS NOT HITTING THIS SUB.
Dim X As String = ""
End Sub
End Class
Public Class ResultCollection
Inherits CollectionBase
Public Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
Default Public Overridable ReadOnly Property Item(ByVal index As Integer) As Result
Get
Return CType(Me.List(index), Result)
End Get
End Property
Public Sub Add(ByVal Result As Result)
List.Add(Result)
End Sub
Public Sub New()
End Sub
Public Sub New(ByVal CycleCountCompletionID As Integer)
Dim CurrCount As Integer = 0
Dim TotalRecords As Integer = 0
Dim SQL As String = [OMITTED]
Dim DS As DataSet = VSMS.GetDataSet(SQL, VSMS.TRIPConnStr)
TotalRecords = DS.Tables(0).Rows.Count
For Each DR As DataRow In DS.Tables(0).Rows
CurrCount += 1
Me.Add(New Result(Convert.ToInt32(DR.
RaiseEvent ResultLoaded(CurrCount, TotalRecords) '<-- EVENT FIRES HERE AND IS HANDLED PROPERLY IF I ADD AN EVENT HANDLER TO THE SAME CLASS
Next
End Sub
End Class
Public Class Completion
' This is the correct statement
Private WithEvents _Results As ResultCollection
' The Error Go Here ... No Need for the "New" Keyword ' Private WithEvents _Results As New ResultCollection
Public Sub LoadResults()
_Results = New ResultCollection(CycleCoun
End Sub
Public Sub _Results_ResultLoaded(ByVa
'EVENT SHOULD BE RAISED HERE, BUT DEBUGGING SHOWS THAT IT IS NOT HITTING THIS SUB.
Dim X As String = ""
End Sub
End Class
Inherits CollectionBase
Public Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
Default Public Overridable ReadOnly Property Item(ByVal index As Integer) As Result
Get
Return CType(Me.List(index), Result)
End Get
End Property
Public Sub Add(ByVal Result As Result)
List.Add(Result)
End Sub
Public Sub New()
End Sub
Public Sub New(ByVal CycleCountCompletionID As Integer)
Dim CurrCount As Integer = 0
Dim TotalRecords As Integer = 0
Dim SQL As String = [OMITTED]
Dim DS As DataSet = VSMS.GetDataSet(SQL, VSMS.TRIPConnStr)
TotalRecords = DS.Tables(0).Rows.Count
For Each DR As DataRow In DS.Tables(0).Rows
CurrCount += 1
Me.Add(New Result(Convert.ToInt32(DR.
RaiseEvent ResultLoaded(CurrCount, TotalRecords) '<-- EVENT FIRES HERE AND IS HANDLED PROPERLY IF I ADD AN EVENT HANDLER TO THE SAME CLASS
Next
End Sub
End Class
Public Class Completion
' This is the correct statement
Private WithEvents _Results As ResultCollection
' The Error Go Here ... No Need for the "New" Keyword ' Private WithEvents _Results As New ResultCollection
Public Sub LoadResults()
_Results = New ResultCollection(CycleCoun
End Sub
Public Sub _Results_ResultLoaded(ByVa
'EVENT SHOULD BE RAISED HERE, BUT DEBUGGING SHOWS THAT IT IS NOT HITTING THIS SUB.
Dim X As String = ""
End Sub
End Class
from help on Raiseevent statement from BOL,
http://msdn.microsoft.com/en-us/library/fwd3bwed(VS.80).aspx
Non-shared events should not be raised within the constructor of the class in which they are declared. Although such events do not cause run-time errors, they may fail to be caught by associated event handlers. Use the Shared modifier to create a shared event if you need to raise an event from a constructor.
So in your case either change the event to be a shared member or change the place from where you are raising the event.
to change to shared event,
Public Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
to
Public Shared Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
http://msdn.microsoft.com/en-us/library/fwd3bwed(VS.80).aspx
Non-shared events should not be raised within the constructor of the class in which they are declared. Although such events do not cause run-time errors, they may fail to be caught by associated event handlers. Use the Shared modifier to create a shared event if you need to raise an event from a constructor.
So in your case either change the event to be a shared member or change the place from where you are raising the event.
to change to shared event,
Public Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
to
Public Shared Event ResultLoaded(ByVal CurrentRecord As Integer, ByVal TotalRecords As Integer)
It's because the "work" is being done from the constructor.
You need to break it out so that the work is in another sub and call it after instantiation.
Try this example out to see the difference:
You need to break it out so that the work is in another sub and call it after instantiation.
Try this example out to see the difference:
Public Class Form1
Private WithEvents cntWrong As CounterWrong
Private WithEvents cntCorrect As CounterCorrect
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
cntWrong = New CounterWrong(5)
cntCorrect = New CounterCorrect(5)
cntCorrect.StartCount()
End Sub
Private Sub cntWrong_Count(ByVal i As Integer) Handles cntWrong.Count
Debug.Print("cntWrong: " & i)
End Sub
Private Sub cntCorrect_Count(ByVal i As Integer) Handles cntCorrect.Count
Debug.Print("cntCorrect: " & i)
End Sub
End Class
Public Class CounterWrong
Public Event Count(ByVal i As Integer)
Public Sub New(ByVal CountTo As Integer)
For i As Integer = 1 To CountTo
RaiseEvent Count(i)
Next
End Sub
End Class
Public Class CounterCorrect
Private _CountTo As Integer
Public Event Count(ByVal i As Integer)
Public Sub New(ByVal CountTo As Integer)
_CountTo = CountTo
End Sub
Public Sub StartCount()
For i As Integer = 1 To _CountTo
RaiseEvent Count(i)
Next
End Sub
End Class
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