A Postgrex.Extension enabling the use of postgresql data types from the isn extension.

In lib/ directory create a file with the following content:

Postgrex.Types.define(MyApp.PostgrexTypes, [ISN], [])

Add the following lines in conig.exs:

config :my_app, MyApp.Repo,

types: MyApp.PostgrexTypes

Then you can do Ecto.Migrations like this:

defmodule MyApp.Repo.Migrations.CreateBook do
  use Ecto.Migration

  def change do
    create table(:books) do
      add :isbn, :isbn13
      # other fields
    end
  end
end

You can also define Ecto.Models using the matching custom Ecto.Types:

defmodule MyApp.Book do
  use MyApp.Web, :model

  schema "books" do
    field :isbn, ISN.ISBN13, read_after_writes: true
    # other fields
  end
end