I cannot get a two-way bind in WPF to work.
I have a string property in my app's main window that is bound to a TextBox (I set the mode to "TwoWay").
The only time that the value of the TextBox will update is when the window initializes.
When I type into the TextBox, the underlying string properties value does not change.
When the string property's value is changed by an external source (an event on Click, for example, that just resets the TextBox's value), the change doesn't propagate up to the TextBox.
What are the steps that I must implement to get two-way binding to work properly in even this almost trivial example?
Best Answer
Most probably you're trying to bind to a .net CLR property instead of a WPF dependencyProperty (which provides Change Notification in addition to some other things).
For normal CLR property, you'd need to implement INotifyPropertyChanged and force update on the textbox in the event handler for PropertyChanged.
This threw me off too when I started learning about WPF data binding.
Update: Well OP, it would have been a waste of time if i was barking up the wrong tree.. anyways now since you had to dig a bit.. you'll remember it for a long time. Here's the code snippet to round off this answer. Also found that updating the textbox happens automatically as soon as I tab-out.. You only need to manually subscribe to the event and update the UI if your datacontext object is not the one implementing INotifyPropertyChanged.
MyWindow.xaml
MyWindow.xaml.cs