Dataview problems [resolved]

[Oliver1]

Okay, I have two combo boxes on a form, both displaying a different column from the same datatable, I want both these combo boxes to be sorted alphabetically though, so I created a dataview as so

ds.Tables.Add("ContactsCom")
ddiView = New DataView(ds.Tables("ContactsCom"))

I then bind the combo boxes as follows

Me.cbocompany.DataSource = ds
        Me.cbocompany.DisplayMember = "ContactsCom.CompanyName"
        Me.cbocompany.ValueMember = "ContactsCom.ContactID"
 
        ddiView.Sort = "MID"
 
        cboddi.DataSource = ddiView
        Me.cboddi.DisplayMember = "MID"
        Me.cbocompany.ValueMember = "ContactID"

Which all seems to work fine, but my problem now is that on the
cbocompany combo box this works

Private Sub cbocompany_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbocompany.SelectedIndexChanged
 
        Try
 
            MsgBox(cbocompany.SelectedValue)
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
 
    End Sub

But on the cboddi box I get the exception

Private Sub cboddi_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboddi.SelectedIndexChanged
        
        Try
            MsgBox(cboddi.SelectedValue)
       
        Catch ex As Exception
            Me.TextBox1.Text = ex.ToString
        End Try
 
    End Sub

System.ArgumentException: Argument 'Prompt' cannot be converted to type 'String'.

Why?

[Shuja Ali]

First thing that I would like to say is that you should not be using MsgBox function in VB.NET. There is a much better method MessageBox.Show that you should always try to use whenever you need to display a messagebox. MsgBox function is there just for backward compatibility with VB 6.0.

Another thing is that you haven't shown which line is erroring out. Is it the Msgbox function or the catch block that giving you problems.

[Oliver1]

This statement gives me a value
cbocompany.SelectedValue
but this doesn't
cboddi.SelectedValue
and errors out saying
System.ArgumentException: Argument 'Prompt' cannot be converted to type 'String'.

The msgbox is only there while I'm trying to find the problem, and in fact I want to use the selectedvalue in another function.
I am aware that you shouldn't really use the msgbox function, but then I'm also aware that drinking is bad for you, but that doesn't stop me doing it

[Shuja Ali]

This is a kind of weired problem. I would suggest that before you bind the comboboxes just remove the handlers. And after you are done with you binding stuff add the handlers back. Something similar to this

RemoveHandler cboddi.SelectedIndexChanged, AddressOf cboddi_SelectedIndexChanged
RemoveHandler cbocompany.SelectedIndexChanged, AddressOf cbocompany_SelectedIndexChanged
 
        ds.Tables.Add("ContactsCom")
ddiView = New DataView(ds.Tables("ContactsCom"))
Me.cbocompany.DataSource = ds
        Me.cbocompany.DisplayMember = "ContactsCom.CompanyName"
        Me.cbocompany.ValueMember = "ContactsCom.ContactID"
 
        ddiView.Sort = "MID"
 
        cboddi.DataSource = ddiView
        Me.cboddi.DisplayMember = "MID"
        Me.cbocompany.ValueMember = "ContactID"
        AddHandler cboddi.SelectedIndexChanged, AddressOf cboddi_SelectedIndexChanged
AddHandler cbocompany.SelectedIndexChanged, AddressOf cbocompany_SelectedIndexChanged

And I have a question for you. When do you actually get this error. Is it when you try to select something in the Combobox or is it before that?

The msgbox is only there while I'm trying to find the problem, and in fact I want to use the selectedvalue in another function.
I am aware that you shouldn't really use the msgbox function, but then I'm also aware that drinking is bad for you, but that doesn't stop me doing it

[Oliver1]

Thanks for your help, turned out to be a really stupid mistake
Me.cbocompany.ValueMember = "ContactID"
should have been
Me.cboddi.ValueMember = "ContactID"

Hence the reason why it didn't work, must have spent about 2 hours on this.