Using jason in hex packages and the trouble with structs about jason HOT 3 CLOSED

For future searchers, we've done this using a custom module which loops through the data and encodes it using Jason: https://github.com/honeybadger-io/honeybadger-elixir/blob/master/lib/honeybadger/json.ex

from jason.

I was thinking, maybe a defimpl could help:

defimpl Jason.Encoder, for: [Map] do
  def encode(%_{} = struct, opts) do
    # pipe through Map.from_struct/1 before passing onto the default implementation
    # or recurse back to the next clause of this function
  end
  def encode(map, opts) do
    # pass on to default implementation
  end
end

I haven't tested this, but this should make it possible without implementing a deep Map.from_struct/1 like discussed in the linked issue.

from jason.

Jason does not define a way to encode arbitrary structs - they always need to be explicitly encoded by either manually encoding to a map (for example by using Map.from_struct) or by deriving the Jason.Encoder protocol. In general, there are many more types that cannot be just encoded to JSON, so tools shouldn't assume they can throw anything at the JSON encoder - some examples are tuples, bitstrings (that are not binaries), pids, ports, references and even binaries that are not UTF-8 encoded. I don't think it's correct for a tool to just try to encode arbitrary data to JSON by passing it to the encoder. If the tool does not want to require users pass JSON-encodable data to it, to should do some pruning and sanitising before encoding.

from jason.