Question

I have an data transfer object called Report. These report objects are held in an observable collection in a different class called Controller. What I am trying to do is create a view that takes data from the Report and displays that in a list.

The problem I am having is that I cannot seem to bind the view properly to the view model. I managed to get it to bind by using a value converter and returning the viewmodel that I need but the Bindings do not seem to resolve even though the view is attached.

The viewmodel that contains the Report list:

public class ReportListViewModel : Screen, IModule
{
    private Controller _controller;
    public Controller Controller
    {
        get { return _controller; }
        set { _controller = value; }
    }

    public ReportListViewModel(Controller controller)
    {
        Controller = controller;
        Controller.Domain.Reports.Add(new Model.Report() { Notes = "Test Data.." });
    }
}

And the XAML view for it:

<Grid Background="Blue">
    <StackPanel>
        <StackPanel.Resources>
            <local:ReportToListItem x:Key="reportToListItem" />
        </StackPanel.Resources>
        <ListBox Height="100" x:Name="Controller_Domain_Reports">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <ContentControl Content="{Binding Converter={StaticResource reportToListItem}}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </StackPanel>
</Grid>

The value converter:

internal class ReportToListItem : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var vm = IoC.Get<ReportListItemViewModel>();
        vm.Report = (Report)value;
        var view = ViewLocator.GetOrCreateViewType(typeof(ReportListItemView));
        ViewModelBinder.Bind(vm, view, null);
        return view;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

And here are the viewmodel and view that are going to be responsible for displaying the data of the Report object.

Viewmodel:

public class ReportListItemViewModel : Screen
{
    private Report _report;
    public Report Report
    {
        get { return _report; }
        set { _report = value; }
    }
}

View:

<Grid>
    <TextBlock Text="{Binding Report, Path=Notes}" />
</Grid>

Now I know that the view is being attached because the OnViewAttached method of the ReportListItemViewModel is triggered. I know the view is being initialed too because it’s constructor is triggered.

But the getter on the ReportListItemViewModel.Report is never called.

So what is going wrong with the Binding?

Answer 1

To load the view automatically with caliburn, you have to bind to Caliburn’s attached properties:

<ContentControl cal:View.Model="{Binding ...}"/>

Otherwise you won’t load the corresponding view into the content control but the viewmodel itself.

Edit:

The stuff above seems to be nonsense, since the OP says the view gets created, also I think I spotted the actual problem:

If you set the binding like this:

<TextBlock Text="{Binding Report, Path=Notes}" />

it won’t work, since you are overwriting the path Report with Notes. To access the Notes property in Report, you have to specify the item like this:

<TextBlock Text="{Binding Report.Notes}" />

or like this:

<TextBlock Text="{Binding Path=Report.Notes}" />