custom_range_types.ex

defmodule LaserRange do 
  @moduledoc """
  This module holds the implementation for the  `LaserRange`
  It implements an `Ecto.Type` behaviour
  """
  @behaviour Ecto.Type
  

  @doc false
  @spec type() :: tuple()
  def type, do: {:array, :integer}

  @doc """
  This function takes a list containg two integers taken as the lower and upper limits 
  of your range 

  Parameters:
  * `lower` - an integer representing the lower limit of the range
  * `upper` - an integer representing the upper limit of the range
  """
  @spec cast(list(integer())) :: {atom(), list(integer())} 
  def cast([lower, upper]) do 
    {:ok, [lower, upper]}
  end 

  def cast(_), do: :error
  
  @doc """
  This function loads our custom type from the Database type
  """
  @spec load(Postgrex.Range.t()) :: {atom(), list(integer())}
  def load(%Postgrex.Range{lower: lower, upper: nil}) do 
    {:ok, [lower, nil]}
  end

  def load(%Postgrex.Range{lower: lower, upper: upper}) do
    {:ok, [lower, upper]}
  end  

  @doc """
  This function takes in our custom type and returns the Database Type
  """
  @spec dump(list(integer())) :: {atom(), Postgrex.Range.t()}
  def dump([lower, upper]) do
    {:ok, %Range{lower: lower, upper: upper, upper_inclusive: true}}
  end 

  def dump(_), do: :error
end