Question

I have a search screen with some textboxes and a Search button as the default. If I type in a textbox and I CLICK the button, everything’s great. But if I press enter within a text box, the button command fires but the binding on whatever text box I was in does NOT fire and so my criteria doesn’t make it to the view model to get filtered on.

I know one fix is to set the bindings on the text boxes to PropertyChanged, but this seems like way overkill. I might have logic in the viewmodel doing stuff and I don’t want that to trigger on every single keystroke.

What I really want is a way for the button itself to either trigger a focus change or somehow trigger binding. Or to have the textbox trigger binding if focus is lost OR I press enter OR a command is executed from anywhere

Answer 1

One way to do this is with a BindingGroup.

http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.bindinggroup.aspx

If your TextBox(es) and Button are both contained within a Grid (for example), you would add a BindingGroup like this:

<Grid>
    <Grid.BindingGroup>
        <BindingGroup Name="bindingGroup1"/>
    </Grid.BindingGroup>

Then you could add a Click event handler to your button and call CommitEdit() on the BindingGroup (which the Button and TextBox inherit from the Grid):

private void button1_Click(object sender, RoutedEventArgs e)
{
    (sender as FrameworkElement).BindingGroup.CommitEdit();
}

The Button.Click event fires before the CommandBinding, so any databound TextBox or any other databound controls within that BindingGroup should be updated before your view model command gets executed.