How do I get a WPF listview to format a byte array as a comma-delimited string?

Question

I'm trying to bind some data to a WPF listview. One of the properties of my data type is of type byte[] and I'd like it to be shown as a comma-delimited string, so for example { 12, 54 } would be shown as 12, 54 rather than as Byte[] Array. I think I want to make a custom DataTemplate but I'm not sure. Is that the best way? If so, how do I do it? If not, what is the best way?

EDIT: I only want to use this for one column - the other properties are displayed fine as they are.

Answer 1

I would create a ValueConverter that creates the comma-delimited string. Then you can bind directly to the byte[], but specify the converter in the binding.

(No need for me to put code when Mark's answer is good.)

Answer 2

I would suggest using a ValueConverter:

[ValueConversion(typeof(byte []), typeof(string))]
public class ByteArrayConverter : IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        byte [] bytes = (byte [])value;
        StringBuilder sb = new StringBuilder(100);
        for (int x = 0; x<bytes.Length; x++)
        {
            sb.Append(bytes[x].ToString()).Append(" ");
        }
        return sb.ToString();
    }

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

    #endregion
}

In your xaml, you'd add it to your binding like this:

<Window.Resources>
    <local:ByteArrayConverter x:Key="byteArrayConverter"/>
</Window.Resources>

...

"{Binding ByteArrayProperty, Converter={StaticResource byteArrayConverter}}"

Answer 3

I set up the following example, which demonstrates the binding using a value converter.

Here is the Window1.xaml.cs:

private ObservableCollection<ByteData> _collection = new ObservableCollection<ByteData>();

public Window1()
{
 InitializeComponent();

 _collection.Add(new ByteData(new byte[] { 12, 54 }));
 _collection.Add(new ByteData(new byte[] { 1, 2, 3, 4, 5 }));
 _collection.Add(new ByteData(new byte[] { 15 }));
}

public ObservableCollection<ByteData> ObservableCollection
{
 get { return _collection; }
}

public class ByteData
{
 byte[] _data;

 public ByteData(byte[] data)
 {
  _data = data;
 }

 public byte[] Data
 {
  get { return _data; }
  set { _data = value; }
 }
}

Here is the Window1.xaml:

<Window x:Class="TestWpfApplication.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TestWpfApplication"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Title="Window1" Height="300" Width="300"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Window.Resources>
 <local:ByteToStringConverter x:Key="byteToStringConverter"/>
</Window.Resources>
<StackPanel>
 <ListView ItemsSource="{Binding ObservableCollection}">
  <ListView.ItemTemplate>
   <DataTemplate>
    <TextBox Width="200" Text="{Binding Path=Data, Mode=TwoWay, 
     UpdateSourceTrigger=PropertyChanged, Converter={StaticResource byteToStringConverter}}"/>
   </DataTemplate>
  </ListView.ItemTemplate>
 </ListView>
</StackPanel>

And here is the value converter:

public class ByteToStringConverter : IValueConverter
{
 public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
 {
  byte[] data = (byte[])value;
  StringBuilder byteString = new StringBuilder();

  int idx;
  for (idx = 0; idx < data.Length - 1; idx++)
  {
   byteString.AppendFormat("{0}, ", data[idx]);
  }
  byteString.Append(data[idx]);

  return byteString.ToString();
 }

 public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
 {
  // If you want your byte-data to be editable in the textboxes, 
  // this will need to be implemented.
  return null;
 }
}