When you have a large object model, annotating it for the WCF serializer (DataContractFormatter) can be tedious. All classes and derived classes need to be annotated with the [DataContract] custom attribute, and all properties need the [DataMember] custom attribute. If you forget a single [DataMember] attribute, no build-time error or run-time will occur, but your program will behave incorrectly and the defect may be difficult to diagnose.

In many cases, what you actually need is to serialize all classes derived from a common base class, and by default all properties should be serialized. This example demonstrates how to address this situation.

The AutoDataContractAttribute aspect automatically adds custom attributes DataContract
to the target and derives classes so they can be serialized by the WCF formatter. By default, the aspect adds the [DataMember] custom attribute to all properties. Properties that must not be serialized must be annotated with the custom attribute NotDataMemberAttribute.

As a result of using AutoDataContractAttribute, you are not forced to pollute your code with [DataContract] and [DataMember] attribute, and most importantly, you will never forget to add a [DataMember] attribute again.

This example demonstrates the use of IAspectProvider and CustomAttributeIntroductionAspect. The AutoDataContractAttribute aspect does not represent any code transformation in itself. Instead, it provides instances of the CustomAttributeIntroductionAspect aspect through the IAspectProvider interface.

Inheritance of the AutoDataContractAttribute aspect from the base class to derived classes is implemented thanks to the [MulticastAttributeUsage(Inheritance = MulticastInheritance.Strict)] custom attribute.