In MVVM model should the model implement INotifyPropertyChanged interface?

by

Implementing INotifyPropertyChanged in Models is totally acceptable –

Typically, the model implements the facilities that make it easy to
bind to the view. This usually means it supports property and
collection changed notification through the INotifyPropertyChanged and
INotifyCollectionChanged interfaces. Models classes that represent
collections of objects typically derive from the
ObservableCollection<T> class, which provides an implementation of the
INotifyCollectionChanged interface.

Although its up to you to decide whether you want that type of implementation or not, but remember –

What if your model classes do not implement the required interfaces?

Sometimes you will need to work with model objects that do not
implement the INotifyPropertyChanged, INotifyCollectionChanged,
IDataErrorInfo, or INotifyDataErrorInfo interfaces. In those cases,
the view model may need to wrap the model objects and expose the
required properties to the view. The values for these properties will
be provided directly by the model objects. The view model will
implement the required interfaces for the properties it exposes so
that the view can easily data bind to them.

Taken from – http://msdn.microsoft.com/en-us/library/gg405484(PandP.40).aspx

I have worked in some projects where we haven’t implemented INotifyPropertyChanged in our models and due to this we faced a lot of issues; unnecessary duplication of properties was needed in VM and at the same time we had to update the underlying object(with updated values) before passing them to BL/DL.

You will face problems specially if you need to work with collection of your model objects(say in an editable grid or list) or complex models; model objects won’t be updated automatically and you will have to manage all that in your VM.

More Related Contents:

  1. Handling Dialogs in WPF with MVVM
  2. How do I set a ViewModel on a window in XAML using DataContext property?
  3. How to pass the UI Dispatcher to the ViewModel
  4. Making sure OnPropertyChanged() is called on UI thread in MVVM WPF app
  5. Custom MVVM implementation Vs. PRISM
  6. How do I use WPF bindings with RelativeSource?
  7. ControlTemplate for existing controls in WPF
  8. Databinding an enum property to a ComboBox in WPF
  9. Dispatcher.CurrentDispatcher vs. Application.Current.Dispatcher
  10. Custom cursor in WPF?
  11. How can I add a hint text to WPF textbox?
  12. Change WPF DataTemplate for ListBox item if selected
  13. WPF: How to make canvas auto-resize?
  14. WPF Data Binding and Validation Rules Best Practices
  15. Where do I get a thread-safe CollectionView?
  16. How to create/make rounded corner buttons in WPF?
  17. WPF MVVM INotifyPropertyChanged Implementation – Model or ViewModel
  18. Why are .NET property wrappers bypassed at runtime when setting dependency properties in XAML?
  19. MVVM show new window from VM when seperated projects
  20. How can I get a ListView GridViewColumn to fill the remaining space in my grid?
  21. “The calling thread must be STA, because many UI components require this” error when creating a WPF pop-up Window in thread
  22. Coerce a WPF TextBox not working anymore in .NET 4.0
  23. What’s the difference between a dependency property and an attached property in WPF?
  24. Can/Does WPF have multiple GUI threads?
  25. Remove Highlight Effect from ListViewItem
  26. Dragging an image in WPF
  27. View Models and dependency injection
  28. Create popup “toaster” notifications in Windows with .NET
  29. Drawing Pixels in WPF
  30. WPF slow to start on x64 in .NET Framework 4.0

Leave a Comment