How to cancel an edit to an object using MVVM?

How can I implement cancelation of editing an object using MVVM.

For example: I have a list of customers. I choose one customer an click the button "Edit", a dialog window(DataContext is binded to CustomerViewModel) opens and I start editing customer's fields. And then I decide to cancel editing, but the fields of the customer have been already changed, so how can I return a customer to its previous state in MVVM?

Solution 1:

Check out the IEditableObject interface. Your Customer class should implement that, and your commands can execute BeginEdit / CancelEdit / EndEdit as appropriate.

Solution 2:

One super easy way, if your object is already serializable, such as if you are using WCF. You can serialize your original object into an internal field. If, your object isn't serializable, then just use AutoMapper to create a copy of your object with one line of code.

Order backup = Mapper.Map<Order, Order>(order);

When you handle your CancelCommand, just call AutoMapper in reverse. Since your properties already have a change notification everything just works. Its possible you could combine these techniques with IEditableObject, if you need and want to write the extra code.