Binding to properties of object within View Model WPF

Question

In my class 'ScheduleViewModel' I have the following property:

private ReminderFilter filter;
public ReminderFilter Filter
{
 get { return filter; }
 set
 {
     filter = value;
     NotifyPropertyChanged("Filter");
 }
}

What I would like to do is bind to the properties of this object without needing to expose them in the View Model. I have tried the following XAML with no success:

<CheckBox IsChecked="{Binding Filter.Complete, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" Content="Show Completed"></CheckBox>

Any suggestions?

Just a quick question, does the `ReminderFilter` implement the `INotifyPropertyChanged` too? Because (afaik) `Filter.Complete` binding should work. — Patryk Ćwiek, Jul 10 '12 at 18:53
did you checked the data binding errors ? whether you have initialized the property? — Moble Joseph, Jul 10 '12 at 18:59
I just changed the ReminderFilter to implement INotifyPropertyChanged but after changing the CheckBoxes IsChecked the set of Complete was not even called. What might i have done wrong? — Chrisjan Lodewyks, Jul 10 '12 at 19:04
Show the XAML that binds the view Datacontext to your VieModel or all what this checkbox is contained in. it smells the binding couldn't find the right datacontext — HichemSeeSharp, Jul 10 '12 at 19:43
Binding is done the same in this control as in all of my other working controls. And the datacontext on other checkboxes are the same as in working controls. — Chrisjan Lodewyks, Jul 10 '12 at 19:52
Yes, on the ScheduleViewmodels constructer I instantiate Filter. — Chrisjan Lodewyks, Jul 10 '12 at 20:00

score 1 · Answer 1 · answered Jul 10 '12 at 19:17

1

I think you need two-way binding. Oneway will only update the view. If you check the checkbox, the value doesn't propagate back down to the object.

answered Jul 10 '12 at 19:17

Josh

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I changed the Mode to Two Way and it still does not call the set of the Complete property. – Chrisjan Lodewyks Jul 10 '12 at 19:22
Check the data binding errors in the output console. This checkbox may not have the datacontext of this viewmodel. – Josh Jul 10 '12 at 19:26
I checked the datacontext of the checkbox and it is set correctly. – Chrisjan Lodewyks Jul 10 '12 at 19:33
When the application is running, view the Output window Ctrl+W,O . Any errors in databinding will be visible there. – Josh Jul 10 '12 at 19:56
I could not find any databinding errors in the output window. – Chrisjan Lodewyks Jul 11 '12 at 10:37

score 0 · Answer 2 · edited May 23 '17 at 12:21

If you want to avoid exposing the property in the view model you will have to implement INotifyPropertyChanged in the ReminderFilter model.

Similar SO Discussion on Get Notified when model properties change

I know you said you would rather not expose the property in the view model but if you were against implementing INotifyPropertyChanged in the model:

    private ReminderFilter filter;
    public bool FilterComplete
    {
        get
        {
            return filter.Complete;
        }
        set
        {
            if (value == filter.Complete)
                return;
            filter.Complete = value;
            NotifyPropertyChanged("FilterComplete");
        }
    }

xaml:

<CheckBox IsChecked="{Binding FilterComplete}" Content="Show Completed"></CheckBox>

Binding to properties of object within View Model WPF

2 Answers2