I just joined this mailing list and have tried to catch up on the
history of this thread, so please excuse me if I’ve missed something.
I’m sorry the Codable API at the moment does not answer your needs —
you’re clearly not the only one who’s run into this, so let’s see
how we can work together to make the API better for everyone.
For one thing, in the case of grabbing a subtree of JSON as
"unevaluated" or "unmapped" (as it appears to be in the metadata case),
it should be fairly simple to add a `JSONDecoder.UnevaluatedJSON` type
that will allow you to essentially decode that part of the tree as an
`Any`. `JSONDecoder` would have knowledge of this type and would be able
to return the subtree inside of it — you’d decode a property as
`JSONDecoder.UnevaluatedJSON.self` and access the contents through `var
value: Any?`, or something similar. This would be simple additive API,
which although might not make it in the upcoming betas, should be fairly
simple introduce. Would this solve that use case?
We’re also working on improving `NSISO8601DateFormatter`. I don’t
think I saw it in any of your emails — what specific use case are you
looking for that it doesn’t at the moment support?
Is this a formal solution that is going to be implemented? This would solve just about every issue I currently have with Decodable.
1) Putting it on `JSONDecoder` seems dubious since you’d only have access to `Decoder` (although conditional casting could solve that). It seems adding the method to `Decoder` and using `Decoder.Unevaluated.self` as the requested type, would be more useful. A user could then conditionally cast that value to things like `[String: Any]` and possibly use its contents generically.
2) Matching it with an equivalent on `Encoder` would be great as well. We take in JSON that has “metaData” like one aforementioned exampled. We then have to send back the equivalent metadata during a subsequent update; without ever inspecting or altering the unevaluated data. Being able encode a `Decoder.Unevaluated` would solve that problem as well.