WPF Databind Before Saving

I found that removing the menu items that are scope depended from the FocusScope of the menu causes the textbox to lose focus correctly. I wouldn't think this applies to ALL items in Menu, but certainly for a save or validate action.

<Menu FocusManager.IsFocusScope="False" >

Assuming that there is more than one control in the tab sequence, the following solution appears to be complete and general (just cut-and-paste)...

Control currentControl = System.Windows.Input.Keyboard.FocusedElement as Control;

if (currentControl != null)
{
    // Force focus away from the current control to update its binding source.
    currentControl.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
    currentControl.Focus();
}

This is a UGLY hack but should also work

TextBox focusedTextBox = Keyboard.FocusedElement as TextBox;
if (focusedTextBox != null)
{
    focusedTextBox.GetBindingExpression(TextBox.TextProperty).UpdateSource();
}

This code checks if a TextBox has focus... If 1 is found... update the binding source!

Suppose you have a TextBox in a window, and a ToolBar with a Save button in it. Assume the TextBox’s Text property is bound to a property on a business object, and the binding’s UpdateSourceTrigger property is set to the default value of LostFocus, meaning that the bound value is pushed back to the business object property when the TextBox loses input focus. Also, assume that the ToolBar’s Save button has its Command property set to ApplicationCommands.Save command.

In that situation, if you edit the TextBox and click the Save button with the mouse, there is a problem. When clicking on a Button in a ToolBar, the TextBox does not lose focus. Since the TextBox’s LostFocus event does not fire, the Text property binding does not update the source property of the business object.

Obviously you should not validate and save an object if the most recently edited value in the UI has not yet been pushed into the object. This is the exact problem Karl had worked around, by writing code in his window that manually looked for a TextBox with focus and updated the source of the data binding. His solution worked fine, but it got me thinking about a generic solution that would also be useful outside of this particular scenario. Enter CommandGroup…

Taken from Josh Smith’s CodeProject article about CommandGroup

Simple solution is update the Xaml code as shown below

    <StackPanel DataContext="{Binding Source={StaticResource MyItemProvider}}"> 
        <Label Content="Enter some text and then File > Save:" /> 
        <TextBox Text="{Binding ValueA, UpdateSourceTrigger=PropertyChanged}" /> 
        <TextBox Text="{Binding ValueB, UpdateSourceTrigger=PropertyChanged}" /> 
    </StackPanel>