Silverlight bound TextBox loses data when browser closes

Question

When I bind a TextBox control to a string property of a object using two way binding, it works fine - as long as the user moves off the control before he closes the browser window/tab.

But what about the user who makes a change to the contents of a text box then closes the window expecting the data to have been saved?

While it is possible to hook into the TextChanged event or Application_Exit() handler and manually update the property, you're essentially re-doing the work of the binder. Nevertheless these seem to be the only solutions so far.

nb. The same xaml/code in a WPF app works fine (App.OnExit shows updated data in object).

Answer 1

Does Silverlight's Binding class have an UpdateSourceTrigger property? In WPF you can tell a control to update its bound source whenever the property changes (rather than when the control loses focus), like this:

<TextBox Text="{Binding Path=Foo,UpdateSourceTrigger=PropertyChanged}" />

Answer 2

I'm making an educated guess here based on significant web development experience but very limited Silverlight experience.

You could use a bit of Javascript to hook into onunload in the HTML and then call a function in your Silverlight code to handle it.

Answer 3

It seems that this is problem with Silverlight. It does not update bound property on text box until it loses focus.

One workaround I had to use (I was implementing dynamic filter) is to implement TextChanged event handler and update backing property manually.