WPF binding textbox to dictionary entry - wpf

Question

i try to bind a wpf textbox to a dictionary placed in a viewmodel. The viewmodel is used as datacontext for the view.
I found a lot of examples and it sounds simple, but it will not work for me.
View:
TextBox x:Name="txbTest" Grid.Row="10" Grid.Column="2" Text="{Binding MyDict[First]}"
ViewModel:
public Dictionary<string, string> MyDict = new Dictionary<string, string>
{
{"First", "Test1"},
{"Second", "Test2"}
};
I try all variants i found
Text="{Binding MyDict[First]}"
Text="{Binding Path=MyDict[First]}"
Text="{Binding MyDict[First].Text}"
Text="{Binding MyDict[First].Value}"
But nothing works, textbox is empty. Any idea?

Answer 1

There is a Binding error in your code because MyDict is not a property. You have to bind to a Property and not to a Field
System.Windows.Data Error: 40 : BindingExpression path error: 'MyDict' property not found on 'object' ''MainWindow' (Name='')'. BindingExpression:Path=MyDict[First]; DataItem='MainWindow' (Name=''); target element is 'TextBox' (Name='textBox1'); target property is 'Text' (type 'String')
Change the MyDict Field to a Property like shown below
private Dictionary<string, string> _MyDict;
public Dictionary<string, string> MyDict
{
get { return _MyDict; }
set { _MyDict = value; }
}
In the constructor of your ViewModel initialize MyDict.
MyDict = new Dictionary<string, string>
{
{"First", "Test1"},
{"Second", "Test2"}
};
The following two variants will not work as MyDict["key"] returns a string and string does not have a Text or Value property. The other two variants should work.
Text="{Binding MyDict[First].Text}"
Text="{Binding MyDict[First].Value}"
The following bindings will work
Text="{Binding MyDict[First]}"
Text="{Binding Path=MyDict[First]}"