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Jul 5th, 2005

Issue related to combobox....

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hi,

I have used a combobox to display a list of options like 1 Month,2 Months,3 Months and last option Other.
Wen i click on "Other" , calender opens and i have to select the date.
The problem is after i select the date and the calender closes i am unable to set the combobox1.text property to the date i selected.
[i am taking the date selected in the global variable].
Please help me with this. :-|

Thanks in advance

vrushalinz1

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Jul 7th, 2005

Re: Issue related to combobox....

Could I see some code? Maybe post some in code tags? Thanks.

npasma

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Jul 8th, 2005

Re: Issue related to combobox....

HI,

Here is the code u asked for,

Private Sub cboExpiryDate_SelectedIndexChanged(ByVal sender As_ System.Object, ByVal e As System.EventArgs) Handles_ cboExpiryDate.SelectedIndexChanged

If cboExpiryDate.Text = "1 Month" Then
'do something
elseif cboExpiryDate.Text = "2 Month" Then
'do something
elseif cboExpiryDate.Text = "3 Month" Then
'do something
ElseIf cboExpiryDate.Text = "Other" Then
'Open a calender and receive the date in a variable m_strExpDate
' i was trying to do as below but wit no results.
cboExpiryDate.Text =m_strExpDate

End Sub

vrushalinz1

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Jul 8th, 2005

Re: Issue related to combobox....

Are you setting the m_strExpDate vairable to the date the user selected on the calender?

Chester

Quote originally posted by vrushalinz1 ...

HI,

Here is the code u asked for,

Private Sub cboExpiryDate_SelectedIndexChanged(ByVal sender As_ System.Object, ByVal e As System.EventArgs) Handles_ cboExpiryDate.SelectedIndexChanged

If cboExpiryDate.Text = "1 Month" Then
'do something
elseif cboExpiryDate.Text = "2 Month" Then
'do something
elseif cboExpiryDate.Text = "3 Month" Then
'do something
ElseIf cboExpiryDate.Text = "Other" Then
'Open a calender and receive the date in a variable m_strExpDate
' i was trying to do as below but wit no results.
cboExpiryDate.Text =m_strExpDate

End Sub

cpopham

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Jul 9th, 2005

Re: Issue related to combobox....

Quote originally posted by cpopham ...

Are you setting the m_strExpDate vairable to the date the user selected on the calender?

Chester

hi,

Yes i assigned the date to the m_strExpDate vairable and tried to display it in the textarea of the combo box.

vrushalinz1

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Jul 13th, 2005

Re: Issue related to combobox....

From your code I see that you are not adding the date chosen to the combobox.

You gotta do two things

1.You should ADD the string to the combo box.To be honest with you,I dont know how to handle combo box,I was thinking combo box and dropdownlist are the same until I read your post and I saw you using something like cboExpiryDate.Text which is not possible in dropdownlist.

In a dropdownlist you can add a new item to the webcontrol by using something like

DropDownList1.Items.Add("My value")

or in your case

DropDownList1.Items.Add(m_strExpDate)

2.Then you gotta ASSIGN the value to the webcontrol by using something like this.

DropDownList1.SelectedItem.Text = m_strExpDate

Hope it helps.

Letscode

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Jul 14th, 2005

Re: Issue related to combobox....

Quote originally posted by Letscode ...

From your code I see that you are not adding the date chosen to the combobox.

You gotta do two things

1.You should ADD the string to the combo box.To be honest with you,I dont know how to handle combo box,I was thinking combo box and dropdownlist are the same until I read your post and I saw you using something like cboExpiryDate.Text which is not possible in dropdownlist.

In a dropdownlist you can add a new item to the webcontrol by using something like

DropDownList1.Items.Add("My value")

or in your case

DropDownList1.Items.Add(m_strExpDate)

2.Then you gotta ASSIGN the value to the webcontrol by using something like this.

DropDownList1.SelectedItem.Text = m_strExpDate

Hope it helps.

Oh thanks a lot, But to be honest i tried with this after i posted this on this forum and got the results. BUt from ur reply i gotto know that v need to add the item first to the list before assigning it to the text area which i was not doin before.

Anyways thanks a lot.

vrushalinz1

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Oct 25th, 2005

Re: Issue related to combobox....

I think I may have a similar issue, but I am searching for a different solution.

I'm using VB.NET 2005 (beta) and I'm trying to assign a value to a Combobox's Text property during a SelectedIndexChanged event. I've placed a ComboBox on a form without changing any of its properties and added the following code:

VB.NET Syntax (Toggle Plain Text)
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If ComboBox1.SelectedIndex = 0 Then
            ComboBox1.Text = "Value retrieved from some function"
        End If
    End Sub
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ComboBox1.Items.Add("Other")
        ComboBox1.Text = "Select an item"
    End Sub
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If ComboBox1.SelectedIndex = 0 Then
            ComboBox1.Text = "Value retrieved from some function"
        End If
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ComboBox1.Items.Add("Other")
        ComboBox1.Text = "Select an item"
    End Sub

I first noticed that "Select an item" appears fine, even though it's not added as an item. However, "Value retrieved..." does not appear when "Other" is selected from the dropdownlist. When stepping through the code, the value of ComboBox1.Text is "Value retrieved...", but when SelectedIndexChanged completes the ComboBox reads "Other".

I know this could be done in VB6. Is this a bug with VB.NET? With VS 2005? Or am I doing something wrong?

Jason Barnett

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Nov 4th, 2005

Re: Issue related to combobox....

I believe I may have come up with a solution, following these steps:

I subclassed the ComboBox and implemented IMessageFilter.
I set a flag when SelectionChangeCommitted fires.
Then I filter for a Paint event and fire a custom event.

If anyone has a better solution, please let me know. In the meantime, here is an example:

Derived Class:

VB.NET Syntax (Toggle Plain Text)
Public Class MyComboBox
    Inherits ComboBox
    Implements IMessageFilter
 
    Private Const WM_PAINT As Integer = &HF
 
    Private iSelectChangeCommit As Boolean = False
 
    ''' <summary>
    ''' Fires when a selection change has completed and before the control is
    ''' painted.
    ''' </summary>
    Public Event SelectionChangeComplete(ByVal sender As Object, ByVal e As System.EventArgs)
 
    Public Sub New()
        Application.AddMessageFilter(Me)
    End Sub
 
    Private Sub MyComboBox_SelectionChangeCommitted(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.SelectionChangeCommitted
        iSelectChangeCommit = True
    End Sub
 
    Private Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
        If m.Msg = WM_PAINT AndAlso iSelectChangeCommit Then
            RaiseEvent SelectionChangeComplete(Me, Nothing)
            Me.SelectionStart = 0
            Me.SelectionLength = Len(Me.Text)
            iSelectChangeCommit = False
        End If
    End Function
 
End Class
Public Class MyComboBox
    Inherits ComboBox
    Implements IMessageFilter

    Private Const WM_PAINT As Integer = &HF

    Private iSelectChangeCommit As Boolean = False

    ''' <summary>
    ''' Fires when a selection change has completed and before the control is
    ''' painted.
    ''' </summary>
    Public Event SelectionChangeComplete(ByVal sender As Object, ByVal e As System.EventArgs)

    Public Sub New()
        Application.AddMessageFilter(Me)
    End Sub

    Private Sub MyComboBox_SelectionChangeCommitted(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.SelectionChangeCommitted
        iSelectChangeCommit = True
    End Sub

    Private Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
        If m.Msg = WM_PAINT AndAlso iSelectChangeCommit Then
            RaiseEvent SelectionChangeComplete(Me, Nothing)
            Me.SelectionStart = 0
            Me.SelectionLength = Len(Me.Text)
            iSelectChangeCommit = False
        End If
    End Function

End Class

Form Code:

VB.NET Syntax (Toggle Plain Text)
Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ComboBox1.Items.Add("Other...")
        ComboBox1.Text = "Select an item"
    End Sub
 
    Private Sub ComboBox1_SelectionChangeComplete(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectionChangeComplete
        ComboBox1.Text = "A Value"
    End Sub
 
End Class
Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ComboBox1.Items.Add("Other...")
        ComboBox1.Text = "Select an item"
    End Sub

    Private Sub ComboBox1_SelectionChangeComplete(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectionChangeComplete
        ComboBox1.Text = "A Value"
    End Sub

End Class

Jason Barnett

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Nov 11th, 2005

Re: Issue related to combobox....

I found a bug in my code...

With a recent project, I received multiple WM_PAINT messages before the iSelectChangeCommit variable was reset. This caused an infinite loop, raising SelectionChangeComplete continuously. The following code reflects the correct order of operations (Note that I reset the variable as soon as I enter the If block).

VB.NET Syntax (Toggle Plain Text)
If m.Msg = WM_PAINT AndAlso iSelectChangeCommit Then
      iSelectChangeCommit = False
      RaiseEvent SelectionChangeComplete(Me, Nothing)
      Me.SelectionStart = 0
      Me.SelectionLength = Len(Me.Text)
End If
If m.Msg = WM_PAINT AndAlso iSelectChangeCommit Then
      iSelectChangeCommit = False
      RaiseEvent SelectionChangeComplete(Me, Nothing)
      Me.SelectionStart = 0
      Me.SelectionLength = Len(Me.Text)
End If

Hope this hasn't caused anyone grief when trying to implement my solution.

Jason Barnett

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