Binding a textblock to dictionary in XAML not displaying value when bound by key

Question

I have a simple program containing a Dictionary with some values in it. At startup I populate the dictionary. But when I bind to the value nothing is displayed. what am I doing wrong?

My class:

class Constants
{
    public static Dictionary<string, string> testDic;

    public Constants()
    {
        testDic = new Dictionary<string, string>();

        testDic.Add("KEY_Test1", "Test 1");
        testDic.Add("KEY_Test2", "Test 2");
        testDic.Add("KEY_Test3", "Test 3");
        testDic.Add("KEY_Test4", "Test 4");

    } 
}

My main:

 public MainWindow()
 {
     Constants con = new Constants();
     InitializeComponent();
 }

My XAML:

<Grid>
    <TextBlock Text="{Binding Path=testDic[KEY_Test3]}"/>
</Grid>

Answer 1

Change your binding to following:

<TextBlock Text="{Binding Path=[KEY_Test3], Source={x:Static local:Constants.testDic}}"/>

Or If you want to do it using the get/set properties, then:

public class Constants
{
    private Dictionary<string, string> testDic;
    public Dictionary<string, string> TestDic
    {
        get { return testDic; }
        set { testDic = value; }
    }
    public Constants()
    {
         TestDic = new Dictionary<string, string>();

         TestDic.Add("KEY_Test1", "Test 1");
         TestDic.Add("KEY_Test2", "Test 2");
         TestDic.Add("KEY_Test3", "Test 3");
         TestDic.Add("KEY_Test4", "Test 4");
    }
}

public partial class MainWindow : Window
{
    private Constants myConstants;
    public Constants MyConstants
    {
        get { return myConstants; }
        set { myConstants = value; }
    }

    public MainWindow()
    {
        MyConstants = new Constants();
        InitializeComponent();
        DataContext = this;
    }
}


<Grid>
    <TextBlock Text="{Binding MyConstants.TestDic[KEY_Test3]}"/>
</Grid>