Question

Is there a way that one can ‘add’ two bindings together and add some strings to them? This is quite hard to explain but one does a binding in your XAML code to a TextBlock for example like this:

<TextBlock Name="FirstName" Text="{Binding FN}" />

What I want to do is this:

<TextBlock Name="FirstLastName" Text="{Binding FN} + ', ' + {Binding LN}" />

So in essence you’ll get something like this:

Dean, Grobler

Thanks in advance!

Answer 1

First that comes to mind is to create additional property in VM that will contain concatenated values:

public string FullName
{
    get { return FN + ", "+ LN; }
}

public string FN
{
    get { return _fN; }
    set 
    {
        if(_fn != value)
        {
            _fn = value;
            FirePropertyChanged("FN");
            FirePropertyChanged("FullName");
        }
    }

}

public string LN
{
    get { return _lN; }
    set
    {
        if(_lN != value)
        {
            _lN = value;
            FirePropertyChanged("LN");
            FirePropertyChanged("FullName");
        }
    }
}

Another approach that might help is to use converter. but in this case we assume that FN and LN are properties of same object:

and

public class PersonFullNameConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (!(value is Person)) throw new NotSupportedException();
        Person b = value as Person;
        return b.FN + ", " + b.LN;
    }

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

public class Person
{
    public string FN { get; set; }
    public string LN { get; set; }
}

and VM:

public Person User
{
    get { return _user; }
    set
    {
        if(_user != value)
        {
            _user = value;
            FirePropertyChanged("User");            
        }
    }
}