Duration Types with Postgrex

As of Ecto 3.12.0, Ecto supports a :duration type which maps to Elixir's Duration struct (available as of Elixir 1.17).

One natural use case for this is when using Postgres's interval type. Historically, Postgrex loads intervals from the database into a custom Postgrex.Interval struct. With the introduction of Duration, there is now the option to choose between the two. Please follow the steps below to enable mapping to Duration.

1. Define your migration

create table("movies") do
  add :running_time, :interval
end

2. Define your schema

defmodule Movie do
  use Ecto.Schema

  schema "movies" do
    field :running_time, :duration
  end
end

3. Define your custom Postgrex type module and specify intervals should decode to Duration

# Inside lib/my_app/postgrex_types.ex

Postgrex.Types.define(MyApp.PostgrexTypes, [], interval_decode_type: Duration)

4. Make Ecto aware of the Postgrex type module in your configuration

config :my_app, MyApp.Repo, types: MyApp.PostgresTypes