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System.Data.DataRowView ComboBox error with VB.NET

I have a combobox whose datasource is a datatable that I fill using a Stored Procedure.

To prevent the combobox selected index changed event from fireing when it is not suppose to, I set the combobox = string.empty after it is filled. Then I use:

if combobox.text = string.empty then
(Dont Do Anything)
Else (Do something)
endif

My problem is that combobox.text = System.Data.DataRowView

How can I make sure my program does nothing if my combobox = System.Data.DataRowView

Dim dt As New Data.DataTable
                Using conn As New Odbc.OdbcConnection(OdbcConnection)
 
                    Using cmd As New Odbc.OdbcCommand("SelectCustno", conn)
                        cmd.CommandType = CommandType.StoredProcedure
 
                        Using da As New Odbc.OdbcDataAdapter(cmd)
 
                            da.Fill(dt)
 
                            With cbbCompanyName
 
                                .DataSource = dt
                                .DisplayMember = "ccustno"
                                .ValueMember = "ccustno"
 
                            End With
 
                        End Using
                    End Using
                End Using
 
            Catch ex As System.Exception
 
                MessageBox.Show(ex.Message)
 
            End Try
 
        End If

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Jorge Paulino

Hi logoncom,

Try to change to this:

        .DisplayMember = "ccustno"
        .ValueMember = "ccustno"
        .DataSource = dt

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logoncom

ASKER

That does not work. Now it is making everything in the combobox equal to System.Data.DataRowView which does me no good.

The problem seems to be that when .displaymember = "ccustno" line is hit, my combobox selected_indexchanged event fires. Since I dont have a value yet my program crashes...Error says "system.data.datarowview can not be converted to string".

How can I make it so that the combobox event does not fire so early? That would solve my problem.

ASKER CERTIFIED SOLUTION

Jorge Paulino

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logoncom

ASKER

It happens on the SelectedValueChanged.

VcCustno is a String variable and is set to be nothing at this point since I dont have the data. However, When I try to fill the combobox, this event fires and the value is neither Nothing or String.Empty... the value at this point is datarowview. So when VcCustno = cbbcompanyname.selectedvalue (system.data.datarowview)... I get the conversion error and program crash.

 Private Sub cbbCompanyName_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbbCompanyName.SelectedValueChanged
 
        If isgoldmine = False Then
 
            If Not vcCustno Is Nothing And vcCustno <> String.Empty Then
                If cbbCompanyName.Text <> String.Empty Then
 
                    vcCustno = cbbCompanyName.SelectedValue
 
                End If
            End If
        End If
 
    End Sub

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Jorge Paulino

Just one question: if you use the same field for the display and the value you don't need to use bought. You can show only the displaymenber (that I think it's fine) and use cbbCompanyName.Text to your work.

logoncom

ASKER

I got it to work by first setting the combobox.datasource = nothing and then refilling it. Issue was I was using the Same combobox to hold two different DataTables depending on User selection... and each one had different .displaymember and .valuemember. That is what I think was happening because now it works

Jorge Paulino

>> Issue was I was using the Same combobox to hold two different DataTables depending on User selection... and each one had different .displaymember and .valuemember.
Ok, you didn't mentioned that! I was finding strange not to work that way.

logoncom

ASKER

This is what I ended up doing along with setting datasource to nothing first