Provide Decoder to turn JSON into Decodable

[aomader]

Hej, it is nice to have JSON as an intermediate correctly-typed abstraction over same JSON data, but at some point I might still want to work with some dedicated data class. However, at that point I might only have the JSON left and I can not make use of some Decoder to turn my JSON into an appropriate Decodable for the task at hand.

I have a concret use case for that, where the concrete structure of my JSON is only clear at a later point in time.

Thus, I would suggest to provide a GenericJSONDecoder to turn a JSON into a Decodable. Analogous to JSONDecoder and Data.

The solution proposed here solves the issue in the meantime, but is really wasteful and rather just a short-time fix:

func decode<T: Decodable>(from json: JSON) throws -> T {
    let data = try JSONEncoder().encode(json)
    return try JSONDecoder().decode(T.self, from: data)
}

[zoul]

Do you dislike the workaround via JSON data in principle (since it is a hack), or does it have particular technical problems for you?

[aomader]

It is not a technical problem, but rather a concern that this is not ideal and can get wasteful for larger JSON structures, as we have to convert back to a JSON string and than into a proper Decodable.

As we have done the JSON parsing already, it makes sense to not redo this work. Also it seems that I am not the only one missing that feature. It is basically a feature request. :)