postgrex

plain.ex

def get_specific_version(id, version, scope) do
  datetime = Timex.parse!(version, "%FT%T.%fZ", :strftime)
             |> Timex.shift(seconds: -1)
             |> Timex.to_datetime
  q = """
  SELECT #{version_fields()} FROM #{table()}
  WHERE id = $1::integer AND sys_period @> $2::timestamptz AND scope @> $3::ltree
  UNION ALL
  SELECT #{version_fields()} from #{history_table()}
  WHERE id = $1::integer AND sys_period @> $2::timestamptz AND scope @> $3::ltree;
  """

  case Ecto.Adapters.SQL.query(Repo, q, [id, datetime, scope]) do
    {:ok, res} -> format_version(res)
    {:error, _} -> raise %NotFoundError{message: "Version #{version} not found"}
  end
end

def format_version(data) do
  cols = Enum.map(data.columns, &(String.to_atom(&1)))
  v = Enum.flat_map(data.rows, fn(r) ->
        Enum.zip(cols, r)
      end)
      |> Enum.into(%{})
      |> Map.update!(:inserted_at, &(Timex.format!(&1, "%FT%T.%fZ", :strftime)))
      |> Map.update!(:updated_at, &(Timex.format!(&1, "%FT%T.%fZ", :strftime)))
  d = if Map.has_key?(v, :schema_version) do
        Map.update!(v, :schema_version, &(Timex.format!(&1, "%FT%T.%fZ", :strftime)))
      else
        v
      end
  {:ok, d}
end