Hi Khaniya,
Actually where is the actual class objects kept.
Suppose your class object is in the user control like
public YourClass CompanyObject
{
get;
set;
}
and your Datagrid is inside the usercontrol , then you can use like,
<DataGridComboBoxColumn Header="Company" ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type UserControl}},Path=CompanyObject.GetCompany}" Width="200"></DataGridComboBoxColumn>
Good luck