JSON encoding

[travisjeffery]

Would be useful to encode to JSON, e.g. map of strings:

BSON.encode_json(doc)
%{"_id" => "559c3c676b92c9bf5c0898fd", "name" => "Travis"}

I'm pretty new to Elixir and this is above my level still, but when I can do it I'll make a PR if there isn't already.

[ericmj]

You can use a JSON library for that, for example https://github.com/devinus/poison.

[travisjeffery]

Right but even then you have to the hardwork of re-encoding them yourself: devinus/poison#66 (comment).

[ericmj]

If you are using master of this library you can implement the protocol for ids:

defimpl Poison.Encoder, for: BSON.ObjectId do
  def encode(id), do: BSON.ObjectId.encode(id)
end

[travisjeffery]

Ah nice!

Here's the implementation in case anyone else hits this:

defimpl Poison.Encoder, for: BSON.ObjectId do
  def encode(id, options) do
    BSON.ObjectId.encode!(id) |> Poison.Encoder.encode(options)
  end
end

Thanks!

[beno]

Where do I add this code? When I try it in various places I always get:

warning: the Poison.Encoder protocol has already been consolidated, an implementation for BSON.ObjectId has no effect

I don't reference Poison.Encoder anywhere else.

[ericmj]

@beno Anywhere in your Elixir files under the lib/ directory.

[beno]

But then I run into the above warning and the code indeed has no effect.

[ericmj]

If you get that warning you have some other issue with your project since you should not get it. If you have some way to share your project I can take a look at it.

[beno]

When I create a new mix app, with 2 dependencies (poison and mongoldb) and just the code above in lib I run into this issue. But interestingly only when I type recompile at the iex prompt, not when I do a full quit/start cycle.

I got confused here, because the initial compile also gives a warning:

warning: function BSON.ObjectId.encode!/1 is undefined or private

So the code above is not valid out of the box. Can you please shed some light on this?

[ericmj]

The recompile issue was a bug in Elixir. Update and it should be fixed.

BSON.ObjectId.encode!/1 is only available on the master branch so far.

[beno]

I was on Elixir 1.3.1, have just now updated to Elixir 1.3.2 but the consolidated protocol warning remains.

@ericmj here is a repo which produces the error https://github.com/beno/consolidate_error

[ericmj]

@beno Please open an issue on the Elixir project if the warning is still happening.

[beno]

Allright, done elixir-lang/elixir#5228