Binding a ComboBox to a relationship

[Ben Reese]

I think that my problem is similar to the one entitled
"Subject: Complicated Data Binding Question" of 7/2/2005

Simply:
I have a pair of combo (dropdown List) boxes that I want to display data in
a parent/child relationship

This is easy to do with dataGrid controls ( Where m_Families is a strongly
typed dataset with 2 tables, Parents and children and a forign key
relationship between them)
-----------------------------------------------------------
DataGridParents.DataSource = m_Families.Parents

DataGridChildren.DataSource = m_Families.Parents
DataGridChildren.DataMember = m_Families.Relations(0).RelationName
-------------------------------------------------------

I cannot see how to do it for Combos. The best I can come up with is to
hadle the position changed event on the binding context of the parent table
and set the child combobox's datasource to the child rows of the current row.
---------------------------------------------------------------
With Me.ComboBoxParents
.DataSource = m_Families.Parents
.DisplayMember = "Name"
.ValueMember = "ID"
End With

AddHandler
Me.BindingContext(m_Families.Parents).PositionChan ged, AddressOf
PositionChanged

Private Sub PositionChanged(ByVal sender As Object, ByVal e As
System.EventArgs)

With Me.ComboBoxChildren

.DataSource =
CType(CType(Me.BindingContext(m_Families.Parents). Current, DataRowView).Row,
DataRow).GetChildRows(m_Families.Relations(0))
.DisplayMember = "Name"
.ValueMember = "ID"
End With
End Sub
---------------------------------------------------------------
I guess that the datagrid must do something similar to this behind the
scenes and I was expecting to get it for free

The problem is then that selecting an item in the child comboBox doesn't
seem to affect the position of the binging context for the child table as it
does when you use datagrids.

What am I missing please

Ben