I don't know if you're still looking to serialize LLBLGen entities to json, but I've got a solution that may work for you. It's built for the Self Servicing pattern (version 2.6), but it probably wouldn't be too hard to make it work with Adapter.
Basically there's a couple of extension methods that let you list fields or related entities (with their fields) and it will serialize everything with minimal code.
Here's an example that would serialize the BuyerName and Price for an Order Entity:
//Result:
//{"BuyerName":"Ben Franklin","Price":49.95}
order.ToJSon(
OrderFields.BuyerName,
OrderFields.Price
);
Here's a larger example that serializes some fields on Order, then some other fields on the related entities Product, Address, and State:
//Result:
//{"BuyerName":"Ben Franklin","Price":49.95,"Product":{"Name":"Headphones"},"Address":{"City":"Oklahoma City","State":{"Name":"Oklahoma"}}}
order.ToJSon(
OrderFields.BuyerName,
OrderFields.Price,
OrderEntity.Relations.ProductEntityUsingProductId.With(
ProductFields.Name
),
OrderEntity.Relations.AddressEntityUsingShippingAddressId.With(
AddressFields.City,
AddressEntity.Relations.StateEntityUsingStateId.With(
StateFields.Name
)
)
);
No promises about the quality, but it has unit tests and it's worked for me so far. Note that you do have to prefetch whatever you want to serialize (it won't do lazy loading).