Elixir Utils

README.md

Elixir

ecto.changeset.ex

defmodule StrawtHat.Ecto.Changeset do
  alias Ecto.Changeset

  def validate_date_range(%Changeset{valid?: true} = changeset, start_field, end_field, opts \\ %{}) do
    start_at = Changeset.get_field(changeset, start_field)
    end_at = Changeset.get_field(changeset, end_field)
    comparison = Map.get(opts, :comparison, :lt) |> datetime_diff_to_timex_diff()

    if Timex.compare(start_at, end_at) == comparison do
      changeset
    else
      Changeset.add_error(changeset, start_field, message(opts, "is out of range"))
    end
  end
  def validate_date_range(changeset, _, _, _, _), do: changeset

  defp message(opts, key \\ :message, default) do
    Keyword.get(opts, key, default)
  end

  defp datetime_diff_to_timex_diff(:lt), do: -1
  defp datetime_diff_to_timex_diff(:gt), do: 1
  defp datetime_diff_to_timex_diff(:eq), do: 0
end