WPF - Set Focus when a button is clicked - No Code Behind

Question

Is there a way to set focus from one control to another using WPF triggers?

Like the following example

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"&gt;
  <Grid>  
    <Grid.RowDefinitions>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
    </Grid.RowDefinitions>

    <TextBox Name="txtName"></TextBox>    
    <TextBox Grid.Row="1" Name="txtAddress"></TextBox>
    <Button Grid.Row="2" Content="Finish">
        <Button.Triggers>
            <EventTrigger RoutedEvent="Button.Click">

                <!-- Insert cool code here-->  

            </EventTrigger>
        </Button.Triggers>
    </Button>
  </Grid>
</Page>

Is there a way for this Event trigger to put to focus on the textBox "txtName"?

I am trying to find the way to do something like this using strict MVVM. If this is something that should not be done via the XAML (in MVVM) then that is fine. But I would like to see some kind of documentation as to how it fit in the MVVM pattern doing it outside the XAML.

Answer 1

not sure but i think you could do something like this:

FocusManager.FocusedElement="{Binding ElementName=txtName}">

Excuse me if im wrong, im not by visual studio so i cant test it out.

Answer 2

Is this what you want?

    <TextBox Name="txtName"></TextBox>
    <TextBox Grid.Row="1" Name="txtAddress"></TextBox>
    <Button Grid.Row="2" Content="Finish">
        <Button.Style>
            <Style TargetType="{x:Type Button}">
                <EventSetter Event="Click" Handler="MoveFocusOnClick" />
            </Style>
        </Button.Style>
        <!--<Button.Triggers>
            <EventTrigger RoutedEvent="Button.Click">
            </EventTrigger>
        </Button.Triggers>-->
    </Button>

c#:

    public void MoveFocusOnClick(object sender, RoutedEventArgs e)
    {
        Keyboard.Focus(txtName); // Or your own logic
    }

Answer 3

Have you considered using an attached behaviour. They are simple to implement and use AttachedProperty's. Although it still requires code, this code is abstracted away in a class and be reused. They can eliminate the need 'code behind' and are often used with the MVVM pattern.

Try this one and see if it works for you.

public class EventFocusAttachment
{
    public static Control GetElementToFocus(Button button)
    {
        return (Control)button.GetValue(ElementToFocusProperty);
    }

    public static void SetElementToFocus(Button button, Control value)
    {
        button.SetValue(ElementToFocusProperty, value);
    }

    public static readonly DependencyProperty ElementToFocusProperty =
        DependencyProperty.RegisterAttached("ElementToFocus", typeof(Control), 
        typeof(EventFocusAttachment), new UIPropertyMetadata(null, ElementToFocusPropertyChanged));

    public static void ElementToFocusPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var button = sender as Button;
        if (button != null)
        {
            button.Click += (s, args) =>
                {
                    Control control = GetElementToFocus(button);
                    if (control != null)
                    {
                        control.Focus();
                    }
                };
        }
    }
}

And then in your XAML do something like...

<Button 
    Content="Click Me!" 
    local:EventFocusAttachment.ElementToFocus="{Binding ElementName=textBox}" 
    />
<TextBox x:Name="textBox" />