Bind linq to DataGridComboBoxColumn - wpf

Question

I am using wpftoolkit from wpf.codeplex.com . While binding a data table(through linq object list) there is a collumn that contains a reference of another table content as a foreign key. So, generally, currently, on that column in datagrid, i want to show a combo box containing the element of another table and selelted item should be from my concerned table. Here is what I am writing:
<dg:DataGrid x:Name="UsersGrid" AutoGenerateColumns="False" CellEditEnding="UsersGrid_CellEditEnding" RowEditEnding="UsersGrid_RowEditEnding" PreviewKeyDown="UsersGrid_PreviewKeyDown">
<dg:DataGrid.Columns>
<dg:DataGridTextColumn Binding="{Binding Path=Id}" Header="Id" Visibility="Hidden" />
<dg:DataGridTextColumn Binding="{Binding Path=Username}" Header="User Name" />
<dg:DataGridTextColumn Binding="{Binding Path=Password}" Header="Password" />
<dg:DataGridTextColumn Binding="{Binding Path=RoleId}" Header="Role ID" />
<dg:DataGridComboBoxColumn x:Name="Roles" ItemsSource="{Binding Path=TVRole}">
</dg:DataGridTemplateColumn>
</dg:DataGrid.Columns>
</dg:DataGrid>
For making the binding, the code behind file contains as the following code:
UsersGrid.ItemsSource = UserManager.GetAllUsers();
Problem is that, I am now don't know what to place in the "ItemsSource" property to achieve what i want for the DataGridComboBoxColumn column . Can anyone please help me? Again mentioning, i want to bind it with linq object.

Answer 1

There is a strange bug with a DataGridComboBoxColumn: the ItemsSource property doesn't support advanced bindings. But you can use DataGridTemplateColumn, and code will be like this:
<DataGrid ItemsSource="{Binding Users}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding Path=Id}" Header="Id" Visibility="Hidden" />
<DataGridTextColumn Binding="{Binding Path=Username}" Header="User Name" />
<DataGridTextColumn Binding="{Binding Path=Password}" Header="Password" />
<DataGridTextColumn Binding="{Binding Path=RoleId}" Header="Role ID" />
<DataGridTemplateColumn>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding Path=DataContext.Roles, RelativeSource={RelativeSource FindAncestor, AncestorType=DataGrid}}"
DisplayMemberPath="Title" SelectedValuePath="Id" SelectedValue="{Binding RoleId, Mode=TwoWay}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
And add this code to the constructor of the View:
var model = new MainViewModel() { Users = UserManager.GetAllUsers(), Roles = UserManager.GetAllRoles() };
this.DataContext = model;
Where the MainViewModel is an auxiliary class:
public class MainViewModel
{
public List<Role> Roles { get; set; }
public List<User> Users { get; set; }
}
Another way is using a list of UserViewModel instead of a list of User, where each viewmodel class contains the list of roles, so it will be possible to use a correct binding. But it is a more complicated solution than above-mentioned one.