Sebb
Tuple keys to json
In Jason/Poison it is possibe to encode tuple values using
defimpl Encoder, for: Tuple do
def encode(data, options) when is_tuple(data) do
data
|> Tuple.to_list()
|> Encoder.List.encode(options)
end
end
But it seems like there is no way no encode maps with tuple keys … right?
EDIT: As possible for values I’m looking for a way to explicitly transform the tuples to a valid json key (a string). For example sth like
defimpl EncoderThatAlsoHandlesKeys, for: Tuple do
def encode(data, options) when is_tuple(data) do
inspect(data)
end
end
which hypothetically would transform:
%{{1,2} => "test"}
to
{"{1,2}": "test"}
Marked As Solved
Sebb
Thanks for the insights guys. conclusion:
- its not possible to hook into encoding of the keys
- if you really want to, do it manually
- or: flatten the maps, eg
%{{1, 2} => %{...}becomes[%{key_: [1, 2], ...}, ...] - for the task I originally had (looking at data) use
inspect(data, pretty: true, limit: infinity) - store data to reuse later in erlang world: use
:erlang.term_to_binaryand:erlang.binary_to_term - in general: JSON - there is some troube under the hood
Also Liked
LostKobrakai
That’s a more long form explanation to that approach.
benwilson512
The way that I’d do this is with an actually explicit transformation. As in, instead of map_with_tuple_keys |> Jason.encode! do map_with_tuple_keys |> keys_to_strings |> Jason.encode! where keys_to_strings/1 goes through and explicitly turns all of your tuple keys into a string of your choosing.
Qqwy
I like the approach @benwilson512 shared.
If you want to explicitly encode your map keys, call a function on your map to turn them into strings before calling Jason.encode! or another encoding function.
You could encode those tuples using inspect().
If you want to be able to decode datatypes later, then inspect cannot help you however: Turning them back into Elixir requires calling Code.eval_string (which is a function of last resort), and will not be able to deal with opaque datatypes like MapSet, Stream, etc. that return an inspect format which starts with a # (as this is read as a comment).
Another approach is using :erlang.term_to_binary (and :erlang.binary_to_term to decode). This supports (with very few exceptions) all datatypes of Elixir/Erlang, and encoding/decoding is quite performant.
Libraries for some other languages besides the BEAM exist as well.
However, this is a binary format and thus it is not humanly readable.
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