call.erl

handle_graphql(Req) ->
    Res = 'Elixir.Chttpd.Graphql':run(),
    io:format("~p", [Res]),
    send_json(Req, {[
        {res, "Res"}
    ]}).

chttpd_graphql.ex

defmodule Chttpd.Graphql do
  def run() do
    doc = """
{
  item(id: "foo") {
    name
  }
}
"""
    Absinthe.run(Chttpd.Schema, variables: %{"id" => "foo"})
  end
end

chttpd_schema.ex

defmodule Chttpd.Schema do
  use Absinthe.Schema

  @fake_db %{
    "foo" => %{id: "foo", name: "Foo", value: 4},
    "bar" => %{id: "bar", name: "Bar", value: 5}
  }

  query do
    @desc "Get an item by ID"
    field :item, type: :item do

      @desc "The ID of the item"
      arg :id, :id

      resolve fn %{id: id}, _ ->
        {:ok, Map.get(@fake_db, id)}
      end
    end
  end

  @desc "A valuable item"
  object :item do
    field :id, :id
    field :name, :string, description: "The item's name"
    field :value, :integer, description: "Recently appraised value"
  end
end

[error] 2016-09-27T22:19:33.767466Z node1@127.0.0.1 <0.625.0> 9541968053 req_err(3420399751) unknown_error : undef
    [<<"Elixir.Exception:normalize/2">>,<<"Elixir.Absinthe:parse/1 L187">>,<<"Elixir.Absinthe:run/3 L254">>,<<"chttpd_misc:handle_graphql/1 L51">>,<<"chttpd:process_request/1 L293">>,<<"chttpd:handle_request_int/1 L229">>,<<"mochiweb_http:headers/6 L122">>,<<"proc_lib:init_p_do_apply/3 L240">>]
[notice] 2016-09-27T22:19:33.767803Z node1@127.0.0.1 <0.625.0> 9541968053 localhost:15984 127.0.0.1 undefined GET /_graphql 500 ok 15