Focus on textBox on the page load with MVVM

Question

I can't set keyboard focus on textbox control when my UI form loads. I am using MVVM pattern and when I tried solution on the following link but this didn't help. When the form loads there is a caret in my textbox but it's not flashing, and I can't write text in it. The same thing happens when I use FocusManager.focused element in XAML. I also tried with Keyboard.Focus(MytextBox) but the same thing happened... Please help anybody, I am stuck 2 days with this...

This is class where i made dependency property IsFocused and used it for binding with isFocused property in my viewmodel:

public  static class Attached
{

public static DependencyProperty IsFocusedProperty = DependencyProperty.RegisterAttached("IsFocused", typeof(bool), typeof(Attached), new UIPropertyMetadata(false, OnIsFocusedChanged));

public static bool GetIsFocused(DependencyObject dependencyObject)
{
    return (bool)dependencyObject.GetValue(IsFocusedProperty);
}

public static void SetIsFocused(DependencyObject dependencyObject, bool value)
{
    dependencyObject.SetValue(IsFocusedProperty, value);
}

public static void OnIsFocusedChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
    TextBox textBox = dependencyObject as TextBox;
    bool newValue = (bool)dependencyPropertyChangedEventArgs.NewValue;
    bool oldValue = (bool)dependencyPropertyChangedEventArgs.OldValue;
    Keyboard.Focus(textBox);
    if (newValue && !oldValue && !textBox.IsFocused)  textBox.Focus();
}

}

This is my XAML:

<TextBox a:Attached.IsFocused="{Binding IsFocused, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}.../>"

possible duplicate of [Set focus on a textbox control in UserControl in wpf](http://stackoverflow.com/questions/19225443/set-focus-on-a-textbox-control-in-usercontrol-in-wpf) — franssu, May 26 '14 at 07:44
Its probably because it's trying to set focus at render time, before the control is loaded, and you can't set focus then. Try using the `Dispatcher` to set the focus at a later `DispatcherPriority`, such as `DispatcherPriority.Loaded`, and I think it will work. — Rachel, May 27 '14 at 18:31

score 2 · Answer 1 · answered May 26 '14 at 07:29

2

In the Window-Element you can write

FocusManager.FocusedElement="{Binding ElementName=textBox}"

answered May 26 '14 at 07:29

Tomtom

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score 2 · Accepted Answer · answered May 26 '14 at 07:30

2

For this u can use your code behind file. In the page loaded event you should do

MyTextBox.Focus();

answered May 26 '14 at 07:30

JMan

2,611
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Since this is UI related only, this approach does not break MVVM pattern. I do the same in my code. – Alexandru Dicu Mar 05 '21 at 07:24

score 0 · Answer 3 · answered May 26 '14 at 07:43

You maybe get a problem with the loaded-timing, meaning you set focus but it gets stolen afterwards. You can try to defer that by using a dispatcher:

myView.Dispatcher.BeginInvoke(new Action(() =>
{
   textBox.Focus();
}), DispatcherPriority.ContextIdle);

Focus on textBox on the page load with MVVM

3 Answers3