I have a WPF user control that contains a DataGrid. This DG contains several columns including a ComboBox for states. The list of states is populated and stored as a property in my ViewModel.
I am trying to bind the StateList Property to the ItemsSource of my Combobox but when I run the form and try to edit the DG, the combobox does not contain any values, the combobox is empty.
Here is the XAML for the usercontrol.
<UserControl x:Class="myproject.View.ucContactView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d" d:DesignHeight="475" d:DesignWidth="977">
<UserControl.Resources>
<ResourceDictionary Source="/Templates/MyResourceDictionary.xaml"/>
</UserControl.Resources>
<Grid DataContext="{Binding ViewModel}">
<DataGrid AutoGenerateColumns="False" ItemsSource="{Binding AddressCollectionViewSource.View}">
<DataGridTemplateColumn Header="State" Width="160">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding StateDescription}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<ComboBox Name="cboState"
SelectedValuePath="StateKey"
ItemTemplate="{StaticResource dtStateTemplate}"
ItemsSource="{Binding StateList}"
SelectedItem="{Binding StateKey, Mode=TwoWay}"
Width="100" />
</StackPanel>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
</DataGrid>
</Grid>
</UserControl>
The odd thing is that if I create another combobox on this usercontrol with the exact same combobox, this combobox works as expected.
<!-- this works as long as it's not in the DG -->
<StackPanel Height="126" HorizontalAlignment="Left" Margin="766,275,0,0" Name="stackPanel1" VerticalAlignment="Top" Width="200" >
<ComboBox Name="cboState2"
SelectedValuePath="StateKey"
ItemTemplate="{StaticResource dtStateTemplate}"
ItemsSource="{Binding StateList}"
SelectedItem="{Binding StateKey, Mode=TwoWay}"
Width="100" />
</StackPanel>
Why won't the combobox in the DG display the values from the StateList property? Any why does the separate combobox work properly?
It's not working because your ComboBox is looking for StateList as a property of the DataContext of the DataGrid. That is, it's trying to bind to ViewModel.AddressCollectionViewSource.View.StateList when it needs to be binding to ViewModel.StateList. Check your output window while debugging and I bet you'll see a binding error to the effect of Could not find property StateList on object AddressCollectionViewSource (or maybe ICollection).
Try this instead:
<ComboBox Name="cboState2"
SelectedValuePath="StateKey"
ItemTemplate="{StaticResource dtStateTemplate}"
ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor,
AncestorType={x:Type DataGrid}}, Path=DataContext.StateList}"
SelectedItem="{Binding StateKey, Mode=TwoWay}"
Width="100" />
if your viewmodel is a property at the window you can do this
ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=ViewModel.StateList, Mode=OneWay}"
<Window x:Class="WpfStackOverflowSpielWiese.Window2"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window2"
Height="300"
Width="300"
x:Name="window">
<Grid DataContext="{Binding ElementName=window, Path=ViewModel}">
<DataGrid x:Name="grid"
AutoGenerateColumns="False"
ItemsSource="{Binding AddressCollectionViewSource, Mode=OneWay}">
<DataGrid.Columns>
<DataGridTemplateColumn Header="State"
Width="160">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding StateKey}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<ComboBox Name="cboState"
SelectedValuePath="StateKey"
ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=ViewModel.StateList, Mode=OneWay}"
SelectedItem="{Binding StateKey, Mode=TwoWay}"
Width="100" />
</StackPanel>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
</Grid>
</Window>
using System.Collections.ObjectModel;
using System.Windows;
namespace WpfStackOverflowSpielWiese
{
/// <summary>
/// Interaction logic for Window2.xaml
/// </summary>
public partial class Window2 : Window
{
public static readonly DependencyProperty ViewModelProperty =
DependencyProperty.Register("ViewModel", typeof(ViewModelClass), typeof(Window2), new PropertyMetadata(default(ViewModelClass)));
public ViewModelClass ViewModel {
get { return (ViewModelClass)this.GetValue(ViewModelProperty); }
set { this.SetValue(ViewModelProperty, value); }
}
public Window2() {
this.InitializeComponent();
this.grid.Items.Clear();
this.ViewModel = new ViewModelClass();
}
}
public class StateClass : DependencyObject
{
public static readonly DependencyProperty StateKeyProperty =
DependencyProperty.Register("StateKey", typeof(string), typeof(ViewModelClass), new PropertyMetadata(default(string)));
public string StateKey {
get { return (string)this.GetValue(StateKeyProperty); }
set { this.SetValue(StateKeyProperty, value); }
}
public static readonly DependencyProperty StateProperty =
DependencyProperty.Register("State", typeof(string), typeof(StateClass), new PropertyMetadata(default(string)));
public string State {
get { return (string)this.GetValue(StateProperty); }
set { this.SetValue(StateProperty, value); }
}
}
public class ViewModelClass : DependencyObject
{
public static readonly DependencyProperty StateListProperty =
DependencyProperty.Register("StateList", typeof(ObservableCollection<string>), typeof(ViewModelClass), new PropertyMetadata(default(ObservableCollection<string>)));
public static readonly DependencyProperty AddressCollectionViewSourceProperty =
DependencyProperty.Register("AddressCollectionViewSource", typeof(ObservableCollection<StateClass>), typeof(ViewModelClass), new PropertyMetadata(default(ObservableCollection<StateClass>)));
public ObservableCollection<StateClass> AddressCollectionViewSource {
get { return (ObservableCollection<StateClass>)this.GetValue(AddressCollectionViewSourceProperty); }
set { this.SetValue(AddressCollectionViewSourceProperty, value); }
}
public ObservableCollection<string> StateList {
get { return (ObservableCollection<string>)this.GetValue(StateListProperty); }
set { this.SetValue(StateListProperty, value); }
}
public ViewModelClass() {
this.StateList = new ObservableCollection<string>(new[] {"one", "two"});
this.AddressCollectionViewSource = new ObservableCollection<StateClass>(new[] {new StateClass {State = "state", StateKey = "one"}});
}
}
}
