From 074c64d91c02ca8d3a7aff05f481f0fa931ec043 Mon Sep 17 00:00:00 2001
From: Lukas Rieder <l.rieder@gmail.com>
Date: Wed, 20 Dec 2017 16:16:30 +0100
Subject: [PATCH] allow to map atoms to other values to handle null -> nil

---
 lib/poison/encoder.ex        | 5 +++++
 test/poison/encoder_test.exs | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/lib/poison/encoder.ex b/lib/poison/encoder.ex
index 2eefc45b..ef15d4e3 100644
--- a/lib/poison/encoder.ex
+++ b/lib/poison/encoder.ex
@@ -74,6 +74,11 @@ defimpl Poison.Encoder, for: Atom do
   def encode(true, _),  do: "true"
   def encode(false, _), do: "false"
 
+  def encode(atom, %{force: mapping} = options) do
+    value = Map.get(mapping, atom, Atom.to_string(atom))
+    Poison.Encoder.encode(value, Map.delete(options, :force))
+  end
+
   def encode(atom, options) do
     Poison.Encoder.BitString.encode(Atom.to_string(atom), options)
   end
diff --git a/test/poison/encoder_test.exs b/test/poison/encoder_test.exs
index c28d1c61..158c1fb2 100644
--- a/test/poison/encoder_test.exs
+++ b/test/poison/encoder_test.exs
@@ -8,6 +8,8 @@ defmodule Poison.EncoderTest do
     assert to_json(true) == "true"
     assert to_json(false) == "false"
     assert to_json(:poison) == ~s("poison")
+    assert to_json(:null) == ~s("null")
+    assert to_json(:null, force: %{null: nil}) == "null"
   end
 
   test "Integer" do