Why is my DataGridComboBoxColumn not populated

Question

Given the XAML block below, the ComboBox named "Populated" shows the items define in the ItemSource when expanded, whereas whilst the DataGridComboBoxColum named "NotPopulated" uses the same ItemSource shows nothing when expanded. (See attached images)

Am I missing something?

<Grid>  
                    <Grid.RowDefinitions>  
                        <RowDefinition Height="*" />  
                        <RowDefinition Height="Auto" />  
                    </Grid.RowDefinitions>  
                    <DataGrid  
                        AutoGenerateColumns="False"  
                        ItemsSource="{Binding SiteModels}"  
                        Style="{StaticResource DefaultStyle}">  
                        <DataGrid.Columns>  
                            <DataGridTextColumn  
                                Binding="{Binding Label}"  
                                Header="Site Model"  
                                IsReadOnly="True" />  
                            <DataGridTextColumn  
                                Binding="{Binding Number}"  
                                Header="# Parts"  
                                IsReadOnly="True" />  
                            <DataGridComboBoxColumn  
                                x:Name="NotPopulated"  
                                Width="*"  
                                DisplayMemberPath="Label"  
                                Header="Pro Model"  
                                ItemsSource="{Binding ProModels}"  
                                SelectedItemBinding="{Binding SelectedItem}" />  
                        </DataGrid.Columns>  
                    </DataGrid>  
                    <ComboBox  
                        x:Name="Populated"  
                        Grid.Row="1"  
                        DisplayMemberPath="Label"  
                        ItemsSource="{Binding ProModels}" />  
                </Grid>  

Answer 1

Hi,
if you don't use static properties you can use StaticResource like in following demo with your code:

XAML:

<Window x:Class="Window075"  
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"  
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"  
        xmlns:local="clr-namespace:WpfApp1"  
        xmlns:vmns="clr-namespace:WpfApp1.WpfApp075"  
        mc:Ignorable="d"  
        Title="Window075" Height="450" Width="800">  
  <Window.Resources>  
    <vmns:ViewModel x:Key="vm"/>  
    <Style x:Key="DefaultStyle"/>  
  </Window.Resources>  
  <Grid DataContext="{StaticResource vm}">  
    <Grid>  
      <Grid.RowDefinitions>  
        <RowDefinition Height="*" />  
        <RowDefinition Height="Auto" />  
      </Grid.RowDefinitions>  
      <DataGrid  
         AutoGenerateColumns="False"  
         ItemsSource="{Binding SiteModels}"  
         Style="{StaticResource DefaultStyle}">  
        <DataGrid.Columns>  
          <DataGridTextColumn  
                 Binding="{Binding Label}"  
                 Header="Site Model"  
                 IsReadOnly="True" />  
          <DataGridTextColumn  
                 Binding="{Binding Number}"  
                 Header="# Parts"  
                 IsReadOnly="True" />  
          <DataGridComboBoxColumn  
                 Width="*"  
                 DisplayMemberPath="Label"  
                 Header="Pro Model"  
                 ItemsSource="{Binding ProModels, Source={StaticResource vm}}"  
                 SelectedValuePath="ID"  
                 SelectedValueBinding="{Binding FK}"/>  
        </DataGrid.Columns>  
      </DataGrid>  
      <ComboBox  
         x:Name="Populated"  
         Grid.Row="1"  
         DisplayMemberPath="Label"  
         ItemsSource="{Binding ProModels}" />  
    </Grid>  
  </Grid>  
</Window>  

and classes see attached txt: 63073-x.txt

Answer 2

Hi David,
in your code ItemsSource of DataGridComboBoxColumn is pointed to property of data item. You must use DataContext of DataGrid for ItemsSource. Try following XAML code:

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <DataGrid
        AutoGenerateColumns="False"
        ItemsSource="{Binding SiteModels}"
        Style="{StaticResource DefaultStyle}">
        <DataGrid.Columns>
            <DataGridTextColumn
                Binding="{Binding Label}"
                Header="Site Model"
                IsReadOnly="True" />
            <DataGridTextColumn
                Binding="{Binding Number}"
                Header="# Parts"
                IsReadOnly="True" />
            <DataGridComboBoxColumn
                x:Name="NotPopulated"
                Width="*"
                DisplayMemberPath="Label"
                Header="Pro Model"
                ItemsSource="{Binding DataContext.ProModels, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"
                SelectedItemBinding="{Binding SelectedItem}" />
        </DataGrid.Columns>
    </DataGrid>
    <ComboBox
        x:Name="Populated"
        Grid.Row="1"
        DisplayMemberPath="Label"
        ItemsSource="{Binding ProModels}" />
</Grid>

Answer 3

Peter,

FYI. I ended up solving it with a combination of your appreciated help and from binding-datagridcomboboxcolumn

Once again, thank you very musch for your help.

David

<DataGridComboBoxColumn
                            Width="*"
                            DisplayMemberPath="Label"
                            Header="Pro Model">
                            <DataGridComboBoxColumn.ElementStyle>
                                <Style>
                                    <Setter Property="ComboBox.ItemsSource" Value="{Binding DataContext.ProModels, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" />
                                </Style>
                            </DataGridComboBoxColumn.ElementStyle>
                            <DataGridComboBoxColumn.EditingElementStyle>
                                <Style>
                                    <Setter Property="ComboBox.ItemsSource" Value="{Binding DataContext.ProModels, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" />
                                </Style>
                            </DataGridComboBoxColumn.EditingElementStyle>
                        </DataGridComboBoxColumn>