Combo Box on VB form locks up application

Posted on 2013-01-28
Medium Priority
Last Modified: 2013-01-29
Here's the issue summary:

Developing in Visual Studio 2012 Pro using a VB.net form
SQL Server 2005 Enterprise backend.

I have a combobox (ddlContractorName) that is databound to a Contractor table.  Its display member returns a string (Fullname), and the selected value returns a  datetime associated with the Fullname for the record.  This sits in a VB form inside a tab container.  Once I click on the combobox it locks up my form.  I can’t exit out, I can’t select any other controls via mouse or keyboard.  I have to stop the program debugger to close it.  This only happens if I populate the Selected Value portion of the combobox.  If I set selected value to none, the form works perfectly.  Only problem is that I need the value for calculations and logic.

I thought this might be caused from the datetime datatype not playing nicely, but it does the same thing when I use a string value for the selected value.

What the heck is causing this?

Here’s the relevant form source code:


Public Class frmHome

    Private Sub FrmHome_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        'TODO: This line of code loads data into the 'Contractor_TrackingDataSet1.SignInOut' table. You can move, or remove it, as needed.
        lblHalt.Visible = False
        lblSignInComplete.Visible = False
        lblSignOutComplete.Visible = False
        btnOKClear.Visible = False

        'TODO: This line of code loads data into the 'Contractor_TrackingDataSet.SignInOut' table. You can move, or remove it, as needed.
        'TODO: This line of code loads data into the 'Contractor_TrackingDataSet.Company' table. You can move, or remove it, as needed.
        'TODO: This line of code loads data into the 'Contractor_TrackingDataSet.Person' table. You can move, or remove it, as needed.
        'TODO: This line of code loads data into the 'Contractor_TrackingDataSet.Person' table. You can move, or remove it, as needed.

    End Sub

    Private Sub ddlContractorName_SelectedIndexChanged(sender As Object, e As EventArgs)

    End Sub

End Class

Question by:jribble
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LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 38828414
Hi ....for what you say this is a databound combobox..with display memer and Value Memeber...
what is your your Value Member ? what is your code to get the SelectedValue?

Author Comment

ID: 38828624
I’m trying to do it through the GUI as opposed to coding it.  Please see attached screenshot.    The sql for the data source is just a “Select * From ContractorTracking.dbo.Person
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 38828678
This is not the proper way....that is why the form freezes...you need as value the safety_training date after each selection ? if so try this
Dim ddlContractorDrv as DataRowView=Ctype(ddlContractorName.SelectedItem,DatarowView)
Dim SelDate as Date=ddlContractorDrv.Item("Safety_Training_Date")

Open in new window

put this code in the Selected index event and set the SelDate where ever you want
Delete the selected value in the databind Mode.Also set the value member the "person_id"
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LVL 18

Accepted Solution

John (Yiannis) Toutountzoglou earned 2000 total points
ID: 38828845
SelectedValue=> None
This the Code
 Private Sub ddlContractorName_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlContractorName.SelectedIndexChanged
            If ddlContractorName.SelectedIndex <> -1 Then

                Dim ddlContractorDrv As DataRowView = CType(Me.ddlContractorName.SelectedItem, DataRowView)
        Dim selDate As Date = CType(ddlContractorDrv.Item("Safety_Training_Date"),Date)
                Me.TextBox1.Text = selDate
            End If
        Catch ex As Exception

        End Try
    End Sub

Open in new window

Hope It Helps!!
LVL 28

Expert Comment

ID: 38829441
Safety_Training_Date should be NOT a "Selected Value" but "Value member" instead
Then, from code, you can access following combo properties:
combo.SelectedIndex - (almost) unbounded integer representing combo item index (though it's equal bindingsource.position)
combo.SelectedValue - equals Safety_Training_Date of selected item
combo.SelectedItem - DataRowView equals bindingsource.Current, you can access to table columns through it, like MsgBox(combo.SelectedItem("Column_Name_Here")) or MsgBox(combo.SelectedItem(Column_Index_Here))
'Note - If option strict set ON then cast SelectedItem first:

Author Closing Comment

ID: 38831617
Worked great!  I really appreciate that you posted the actual code.
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 38831731
Glad to help you

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