How to setup a WPF datatemplate in code for a treeview?

Question

struct Drink
{
    public string Name { get; private set; }
    public int Popularity { get; private set; }

    public Drink ( string name, int popularity )
        : this ( )
    {
        this.Name = name;
        this.Popularity = popularity;
    }
}

List<Drink> coldDrinks = new List<Drink> ( ){
    new Drink ( "Water", 1 ),
    new Drink ( "Fanta", 2 ),
    new Drink ( "Sprite", 3 ),
    new Drink ( "Coke", 4 ),
    new Drink ( "Milk", 5 ) };
        }
    }

So that I can see the Name property for treeview item names.

Answer 1

There are two approaches. The easiest is to just generate the xaml, and parse it at runtime:

string xaml = "<DataTemplate><TextBlock Text=\"{Binding Name}\"/></DataTemplate>";
MemoryStream sr = new MemoryStream(Encoding.ASCII.GetBytes(xaml));
ParserContext pc = new ParserContext();
pc.XmlnsDictionary.Add("", "http://schemas.microsoft.com/winfx/2006/xaml/presentation");
pc.XmlnsDictionary.Add("x", "http://schemas.microsoft.com/winfx/2006/xaml");
DataTemplate datatemplate = (DataTemplate)XamlReader.Load(sr, pc);
treeView1.Resources.Add("dt", datatemplate);

The second option is to use the FrameworkElementFactory class . However, this is quite involved, and difficult to get "right". As MSDN now refers to this as deprecated, I won't include code to demonstrate...

Answer 2

Instead of creating your own XAML like Reed said you can get a control XAML by using

String myXAML = System.Windows.Markup.XamlWriter.Save(yourControl.Template)

You can then edit the XAML and create back your controltemplate/datatemplate

var xamlStream = new MemoryStream(System.Text.Encoding.Default.GetBytes(myXAML));
_buttonControlTemplate = (ControlTemplate)System.Windows.Markup.XamlReader.Load(xamlStream);

Answer 3

Reed has already covered the "build your own XAML" approach, but just to provide an illustration of the FrameworkElementFactory approach, it would look something like this.

First, create the FEF:

var fef = new FrameworkElementFactory(typeof(TextBlock));
fef.SetBinding(TextBlock.TextProperty, new Binding("Name"));

Then create a DataTemplate with its VisualTree set to that factory:

DataTemplate dt = new DataTemplate { VisualTree = fef };

Although as Reed notes the FrameworkElementFactory approach is officially deprecated, it is still reasonably widely used, I guess because building XAML strings feels so kludgy. (Though the FEF approach rapidly becomes insanely complicated if you have a non-trivial template...!)