Absinthe enums from Ecto enums

absinthe_enums_from_ecto_enums.ex

@doc """
Takes a list of Ecto.Enum fields and converts them into Absinthe enum
types.

## Usage

The list consists of tuples with the name of the GraphQL enum, the Ecto schema
module and the schema field using `Ecto.Enum`.

    use Absinthe.Schema.Notation
    import ModuleThatDefinesMacro

    absinthe_enums_from_ecto_enums([
      {:type_name, MyApp.SomeSchema, :some_field}
    ])
"""
defmacro absinthe_enums_from_ecto_enums(enums) when is_list(enums) do
  for {_, _, [name, module, field]} <- enums do
    module = Macro.expand(module, __CALLER__)
    values = Ecto.Enum.values(module, field)

    quote do
      enum(unquote(name), values: unquote(values))
    end
  end
end