I'm trying to bind each view model in an ObservableCollection<FilterControlViewmodel>
as DataContext
to a user control FilterControl
in an ItemsControl
.
The binding itself works fine. "InitialFilterName"
is displayed correctly from FilterControlViewmodel.FilterName
but any updates on the property are not notified to the UI.
Also adding elements to ObservableCollection<FilterControlViewmodel>
is working find and adding additional user controls. But again the values inside the FilterControlViewmodel
are not updated to the UI.
Any hint on where the notification is missing is appreciated. Thanks.
MainWindow.xaml
<Window.DataContext>
<local:MainWindowViewmodel/>
</Window.DataContext>
<Grid>
<ItemsControl ItemsSource="{Binding FilterViewmodel.FilterControls}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<filter:FilterControl DataContext="{Binding}"></filter:FilterControl>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
FilterControl.xaml
<UserControl.DataContext>
<local:FilterControlViewmodel/>
</UserControl.DataContext>
<Grid>
<Label Grid.Column="0" Grid.Row="0" Content="{Binding FilterName}"></Label>
<ComboBox Grid.Column="0" Grid.Row="1" ItemsSource="{Binding FilterValues}" SelectedItem="{Binding FilterValueSelected}"></ComboBox>
<Button Grid.Column="1" Grid.Row="1" Content="X" Command="{Binding ResetFilterCommand}"></Button>
</Grid>
MainWindowViewmodel.cs
public class MainWindowViewmodel : INotifyPropertyChanged
{
public FilterViewmodel FilterViewmodel
{
get => _filterViewmodel;
set
{
if (Equals(value, _filterViewmodel)) return;
_filterViewmodel = value;
OnPropertyChanged();
}
}
FilterViewmodel.cs
public class FilterViewmodel : INotifyPropertyChanged
{
public ObservableCollection<FilterControlViewmodel> FilterControls
{
get => return _filterControls;
set
{
if (Equals(value, _filterControls)) return;
_filterControls = value;
OnPropertyChanged();
}
}
FilterControlViewmodel.cs
public class FilterControlViewmodel : INotifyPropertyChanged
{
private string _filterName = "InitialFilterName";
public string FilterName
{
get => _filterName;
set
{
if (value == _filterName) return;
_filterName = value;
OnPropertyChanged();
}
}
You should remove the following markup as it creates another instance of FilterControlViewmodel
:
<UserControl.DataContext>
<local:FilterControlViewmodel/>
</UserControl.DataContext>
The FilterControl
will then inherit its DataContext
from the current item (FilterControlViewmodel
) in the ItemsControl
without you having to set the DataContext
property explicitly:
<ItemsControl ItemsSource="{Binding FilterViewmodel.FilterControls}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<filter:FilterControl/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>