def deps do
  [
    ...
    {:ecto_ltree, "~> 0.3.0"}
  ]
end

def deps do
  [
    ...
    {:ecto_ltree, "~> 0.2.0"}
  ]
end

def deps do
  [
    ...
    {:ecto_ltree, "~> 0.1.0"}
  ]
end

Postgrex.Types.define(
  MyApp.PostgresTypes,
  [EctoLtree.Postgrex.Lquery, EctoLtree.Postgrex.Ltree] ++ Ecto.Adapters.Postgres.extensions()
)

  config :my_app, MyApp.Repo,
    adapter: Ecto.Adapters.Postgres,
    username: "postgres",
    password: "postgres",
    database: "my_app_dev",
    hostname: "localhost",
    poolsize: 10,
    pool: Ecto.Adapters.SQL.Sandbox,
    types: MyApp.PostgresTypes

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

  def change do
    execute("CREATE EXTENSION ltree",
            "DROP EXTENSION ltree")
  end
end

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

  def change do
    create table(:items) do
      add :path, :ltree
    end

    create index(:items, [:path], using: :gist)
  end
end

defmodule MyApp.Item do
  use Ecto.Schema
  import Ecto.Changeset
  alias EctoLtree.LabelTree, as: Ltree

  schema "items" do
    field :path, Ltree
  end

  def changeset(item, params \\ %{}) do
    item
    |> cast(params, [:path])
  end
end

iex(1)> alias MyApp.Repo
MyApp.Repo
iex(2)> alias MyApp.Item
MyApp.Item
iex(3)> import Ecto.Query
Ecto.Query
iex(4)> import EctoLtree.Functions
EctoLtree.Functions
iex(5)> Item.changeset(%Item{}, %{path: “1.2.3”}) |> Repo.insert!
%MyApp.Item{
  __meta__: #Ecto.Schema.Metadata<:loaded, “items”>,
  id: 1,
  path: %EctoLtree.LabelTree{labels: [“1”, “2”, “3”]}
}
iex(6)> from(item in Item, select: nlevel(item.path)) |> Repo.one
3