WPF ListView Data Binding?

Question

I have a collection of objects that I wish to bind to a ListView control. In some of the objects, the value of a property that will be displayed in a column in the ListView is an empty string (""). I want to replace the empty string ("") with "n/a" automatically using binding.

How can I accomplish this?

Answer 1

You could always add a read only property to your bound object that formatted what you wanted to display.

public string Property
{
  get;
  set;
}
public string PropertyDescriptor
{
  get
  {
    if (string.IsNullOrEmpty(this.Property))
      return "n/a";
    else
      return this.Property;
  }
}

This works quite well if you're using MVVM.

Answer 2

    public string MyProperty 
    { 
        get
        {
            if (String.IsNullOrEmpty(_myProperty))
                return "n/a";
            else
                return _myProperty;
        }
        set 
        {
            if (_myProperty != value)
            { 
                _myProperty = value;
                RaisePropertyChanged("MyProperty")
            }
        }
    }

Answer 3

Define a value converter:

class EmptyToN_AConverter : IValueConverter
{
    public object Convert(
        object value, 
        Type targetType, 
        object parameter, 
        System.Globalization.CultureInfo culture)
    {
        string s = value.ToString();
        if (string.IsNullOrEmpty(s)) return "N/A";
        return s;
    }

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

Example XAML:

<Window.Resources>
  ...
    <local:EmptyToN_AConverter x:Key="NAConverter"/>
</Window.Resources>

...{Binding Path=TheProperty, Converter={StaticResource NAConverter}}...

You may even parameterize the converter and expose the "N/A" in XAML:

    public object Convert(
        object value, 
        Type targetType, 
        object parameter, 
        System.Globalization.CultureInfo culture)
    {
        string s = value.ToString();
        if (string.IsNullOrEmpty(s)) return parameter.ToString();
        return s;
    }

...{Binding Path=TheProperty, 
            Converter={StaticResource NAConverter}, 
            ConverterParameter=N/A}...

Answer 4

Use the BindingBase.TargetNullValue property :

<GridViewColumn DisplayMemberBinding="{Binding MyProperty, TargetNullValue=N/A}"/>

EDIT: as pointed out by Aviad, this will only work for a null value, not an empty string. I don't delete this answer because it can still be useful to others.