Change Tracking example: limitations

A significant limitation of the aspects implemented in the articles above is that they only support fields of immutable type. When a change is made in a child object without changing the field referencing the child object, the IsChanged property will not be modified. The most common examples are child collections, typically stored in read-only fields or properties.

There are several strategies to mitigate this limitation:

• Manually call OnChange from collection operations.
• Use immutable collections.
• Create change-tracking collection classes.

Unless you create change-tracking collection classes, you must design your class to expose the collections as read-only interfaces to prevent the caller code from skipping the call to OnChange. You could add code to the BuildAspect method to verify that all exposed fields are immutable or implement the change-tracking mechanism.

If you have an object model with parent-child relationships, you may need to call the OnChange method of the parent object when any child object is being modified.