From d271446d4b8613f40f0ea3d0e0a645d44b451ed8 Mon Sep 17 00:00:00 2001
From: Ilja Tkachuk <ilja@heathmont.net>
Date: Thu, 12 Dec 2019 14:40:39 +0200
Subject: [PATCH] allow empty enums

---
 lib/ecto_enum/postgres/use.ex |  6 +++++-
 lib/ecto_enum/typespec.ex     |  3 +++
 lib/ecto_enum/use.ex          |  6 +++++-
 test/ecto_enum_test.exs       | 12 ++++++++++++
 4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/lib/ecto_enum/postgres/use.ex b/lib/ecto_enum/postgres/use.ex
index 4676668..a9c9c2d 100644
--- a/lib/ecto_enum/postgres/use.ex
+++ b/lib/ecto_enum/postgres/use.ex
@@ -9,7 +9,9 @@ defmodule EctoEnum.Postgres.Use do
 
       @behaviour Ecto.Type
 
-      @type t :: unquote(typespec)
+      if typespec do
+        @type t :: unquote(typespec)
+      end
 
       enums = input[:enums]
       valid_values = enums ++ Enum.map(enums, &Atom.to_string/1)
@@ -49,6 +51,8 @@ defmodule EctoEnum.Postgres.Use do
         def load(unquote(string)), do: {:ok, unquote(atom)}
       end
 
+      def load(_), do: :error
+
       def valid_value?(value) do
         Enum.member?(unquote(valid_values), value)
       end
diff --git a/lib/ecto_enum/typespec.ex b/lib/ecto_enum/typespec.ex
index cb72d4e..ad7f5b1 100644
--- a/lib/ecto_enum/typespec.ex
+++ b/lib/ecto_enum/typespec.ex
@@ -1,6 +1,9 @@
 defmodule EctoEnum.Typespec do
   @moduledoc "Helper for generating enum typespecs"
 
+  def make([]), do: nil
+  def make(%{} = x) when map_size(x) == 0, do: nil
+
   def make(enums) do
     enums
     |> Enum.reverse()
diff --git a/lib/ecto_enum/use.ex b/lib/ecto_enum/use.ex
index 292da2a..a407827 100644
--- a/lib/ecto_enum/use.ex
+++ b/lib/ecto_enum/use.ex
@@ -9,7 +9,9 @@ defmodule EctoEnum.Use do
 
       @behaviour Ecto.Type
 
-      @type t :: unquote(typespec)
+      if typespec do
+        @type t :: unquote(typespec)
+      end
 
       keys = Keyword.keys(opts)
       string_keys = Enum.map(keys, &Atom.to_string/1)
@@ -52,6 +54,8 @@ defmodule EctoEnum.Use do
         def load(unquote(value)), do: {:ok, unquote(key)}
       end
 
+      def load(_), do: :error
+
       def valid_value?(value) do
         Enum.member?(@valid_values, value)
       end
diff --git a/test/ecto_enum_test.exs b/test/ecto_enum_test.exs
index 0a7f10b..dcd9f46 100644
--- a/test/ecto_enum_test.exs
+++ b/test/ecto_enum_test.exs
@@ -287,6 +287,18 @@ defmodule EctoEnumTest do
               ]}
   end
 
+  test "allow empty enums" do
+    require EctoEnum
+
+    EctoEnum.defenum(
+      Void,
+      :void,
+      []
+    )
+
+    assert Void.__enums__() == []
+  end
+
   def custom_error_msg(value) do
     "Value `#{inspect(value)}` is not a valid enum for `EctoEnumTest.StatusEnum`." <>
       " Valid enums are `#{inspect(StatusEnum.__valid_values__())}`"