Validation is not getting fired when setting updatesourcetrigger to lost focus - wpf

Question

I am using below code to validate textbox.
<TextBox.Text>
<Binding Path="Name" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True">
<Binding.ValidationRules>
<Validate:RquiredFiledValidation ErrorMessage="Please Provide Login Name"></Validate:RquiredFiledValidation>
</Binding.ValidationRules>
</Binding>
Above code is working fine but when changing updatesourcetrigger to Lostfocus it stop working.
<TextBox.Text>
<Binding Path="Name" UpdateSourceTrigger="LostFocus" ValidatesOnDataErrors="True">
<Binding.ValidationRules>
<Validate:RquiredFiledValidation ErrorMessage="Please Provide Login Name"></Validate:RquiredFiledValidation>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
Any help would be appreciated.

Answer 1

The spelling of Field is wrong:
<Validate:RquiredFieldValidation ErrorMessage="Please Provide Login Name"></Validate:RquiredFieldValidation>
UPDATE:
From the UpdateSourceTrigger Enumeration page on MSDN:
PropertyChanged: Updates the binding source immediately whenever the binding target property changes, which means that the source value will be updated each time the bound property changes.
whereas
LostFocus: Updates the binding source whenever the binding target element loses focus i.e., the source value will be updated each time the destination control loses focus. If you don’t make any property change on target, source will stay the same.
As Jim Zhou says here, we could invoke the BindingExpression.UpdateSource method to force the data source to reset. So in this case, we can hook up LostFocus event on the TextBox and invoke the
BindingExpression.UpdateSource method explicitly. Something like this:
private void OnLostFocus(object sender, RoutedEventArgs e)
{
TextBox text = sender as TextBox;
BindingOperations.GetBindingExpression(text, TextBox.TextProperty).UpdateSource();
}
Also have a look at ValidatesOnTargetUpdated property of ValidationRule. It will validate when the data is first loaded. This is good if you're trying to catch empty or null fields. Than you can add something like this in your Binding Validation rule:
<DataErrorValidationRule ValidatesOnTargetUpdated="True" />
Not much related but you may like dkozl's answer.
Hope that helps.:)