Question

I have

class Student
{
public List<Degree> Degrees {get;set;}

}

class Degree
{
public Subject Subject{get;set;}

public int Value {get;set;}
}

class Subject 
{
English =0,
Germany = 1,
Biology=2
}

And I have a Treeview

<HierarchicalDataTemplate DataType="{x:Type MyService:Student}" >
<TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="English: "/>
<CheckBox IsChecked="{Binding Path=Degrees.Where(d=>d.Subject==English).First()}, Converter={StaticResource degreeToBoolIsPassed}"> </CheckBox>
<TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="Germany: "/>
<CheckBox IsChecked="{Binding Path=Degrees.Where(d=>d.Subject==Germany).First()}, Converter={StaticResource degreeToBoolIsPassed}"> </CheckBox>
etc

Architecture of classed couldn’t be change ,degreeToBoolIsPassed is easy to do, so I’m only want to xaml from you, or .cs of this control.
I know that:

<CheckBox IsChecked="{Binding Path=Degrees.Where(d=>d.Subject==Germany).First()}, Converter={StaticResource degreeToBoolIsPassed}"> </CheckBox>

doesn’t work. It is only example what I want.

Important thing:

Every student must have 4 checkboxes

Answer 1

You will need a ValueConverter:

Bind to Degrees:

IsChecked="{Binding Path=Degrees, Converter={StaticResource DegreesConverter}, ConverterParameter={x:Static namespace:Subject.Germany}}

Implement a nice converter somewhere:

public class DegreesConverter: IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        List<Degree> degrees = (List<Degree>) value;
        return degrees.Any(d => Equals(d.Subject, (Subject)parameter));
    }

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

    #endregion
}

Register your converter in the resources somewhere under the key DegreesConverter like so:

<namespace:DegreesConverter x:Key="DegreesConverter" />

Note that the namespace prefix should also be registered in the Control you are using this stuff in, but I think you will know how to do this!

Good luck!