Thoughts on improving JsonSerializer. IMappingResolver?

Carl: "According to the map, the cabin should be right here." Lenny: "Hey, maybe there is no cabin. Maybe it's one of them metaphorical things." Carl: "Oh yeah, yeah... Like maybe the cabin is the place inside each of us, created by our goodwill and teamwork." Lenny: "Oh! ... Nah, they said there would be sandwiches." JsonSerializer is pretty darn flexible. It has a half dozen options on the class to customize how an object is serialized, attributes for more fine grained control and finally JsonConverters if you need to do something completely different.

The most popular request I get these days is control over how JsonSerializer determines what members on a type to serialize (e.g. serialize private as well as public properties) and control over the name of the written property (e.g. instead of “FirstName” write the property camelcase style: “firstName”).

Controlling this behaviour is actually already possible by inheriting from JsonSerializer and overriding GetMemberMappings. The MemberMapping class contains all the information about how a .NET member gets mapped to a JSON property (name, readable, writable, converter, etc) and is used internally by JsonSerializer. The problem is it isn’t terribly discoverable to the average user.


What I am thinking of doing is adding is an IMappingResolver interface.

public interface IMappingResolver
  JsonMemberMappingCollection ResolveMappings(Type type);

JsonSerializer would have a MappingResolver property and the instance of the object assigned to it would determine how the members on a .NET class get mapped to a JSON object (if you’re hip with the GOF urban street lingo this is an example of the strategy pattern).

Examples of resolvers that could come with Json.NET or you could create yourself: CamelCaseMappingResolver, TypeDescriptorMappingResolver, PrivateMembersMappingResolver and so on.

I like this over inheritance because it is obvious and in a user’s face. MappingResolver could also be added to the JsonSerializerSettings class and used from the serialization helper methods on JsonConvert.

Yay or nay? Suggestions welcome [:)]