IDataErrorInfo interface is really handy when implementing data validation in WPF. There are many different ways to implement IDataErrorInfo for a DataContext. But since I've recently become quite fond of FluentValidation library for implementing validators, I'm going to focus on using it in this post.
XAML has first class syntax support for binding to indexed properties, such as Dictionary. Real properties still have their advantages over indexed ones, such as full support for implementing INotifyPropertyChanged. For Dictionary properties this can only be done for all items in the collection at once. Unfortunately, in Windows Store applications this causes problems when there are bindings to keys that are not present in the new Dictionary.
One of the challenges of using MVVM pattern with different UI frameworks that always comes up is how to bind events that are not exposed as commands to the view model. Windows Store apps are no exception to that. In this blog post I'll try to give an overview of the available possibilities one can choose from based on individual requirements and personal preferences.
When you pass an instance of IList<T> to the constructor, the BindingList<T> doesn't create its copy. It serves as a wrapper for it, supporting only the operations also supported by the underlying collection.