The Mode property of the , which is the default for the Text property of the Text Box control, the text you type into the Text Box does not update the source property until the control loses focus which happens when you click away from it. the setter for the bound property of the Data Context to get called, as the user is typing into the Text Box you set the Update Source Trigger property to enumeration.Setting the property to this value means that the value of the source property only gets updated when you explicitly call the Binding Expression. You will typically never use this approach in an MVVM application though.
This post is about how data validation works in WPF and the different validation options there are available including implementing custom Validation Rules and using the In a typical WPF application that uses the MVVM (Model-View-View Model) design pattern, a dependency property of a user interface control in a XAML-defined view uses data binding to bind to some data returned by a CLR property of the view model.
If the binding is setup correctly and the view model implements the interface to provide notifications when the data changes, the changes are automatically reflected in the elements in the view that are bound to it.
I need validations for my Text Box, it should show errors as I enter wrong characters or integers.
Also can this be done only in Xaml without codebehind?
And use error template to display your errors to user in UI.