From 15e6c650d5df2922c4e77184fe13c827cb111cdb Mon Sep 17 00:00:00 2001
From: Michal Muskala <michal@muskala.eu>
Date: Tue, 15 Dec 2015 22:50:57 +0100
Subject: [PATCH] Make sure we don't allow fields as values

---
 lib/mongo_ecto/conversions.ex | 4 +++-
 lib/mongo_ecto/utils.ex       | 6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/mongo_ecto/conversions.ex b/lib/mongo_ecto/conversions.ex
index b282559..a7987ea 100644
--- a/lib/mongo_ecto/conversions.ex
+++ b/lib/mongo_ecto/conversions.ex
@@ -44,8 +44,10 @@ defmodule Mongo.Ecto.Conversions do
     do: document(keyword, pk)
   def from_ecto_pk(list, pk) when is_list(list),
     do: map(list, &from_ecto_pk(&1, pk))
-  def from_ecto_pk(value, _pk),
+  def from_ecto_pk(value, _pk) when is_literal(value),
     do: {:ok, value}
+  def from_ecto_pk(value, _pk),
+    do: :error
 
   defp document(doc, pk) do
     map(doc, fn {key, value} ->
diff --git a/lib/mongo_ecto/utils.ex b/lib/mongo_ecto/utils.ex
index 248801e..6096987 100644
--- a/lib/mongo_ecto/utils.ex
+++ b/lib/mongo_ecto/utils.ex
@@ -7,4 +7,10 @@ defmodule Mongo.Ecto.Utils do
       unquote(doc) |> hd |> tuple_size == 2
     end
   end
+
+  defmacro is_literal(value) do
+    quote do
+      is_atom(unquote(value)) or is_number(unquote(value)) or is_binary(unquote(value))
+    end
+  end
 end