From 039d219031db44c2a915456cd42b1db0f2487d9b Mon Sep 17 00:00:00 2001
From: Tomasz Kowal <tomekowal@gmail.com>
Date: Sun, 22 Dec 2024 13:23:05 +0000
Subject: [PATCH] Document usage of ParametrizedType inside of a composite type

---
 lib/ecto/parameterized_type.ex | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/ecto/parameterized_type.ex b/lib/ecto/parameterized_type.ex
index 0fab2f08e8..187b7a9b0b 100644
--- a/lib/ecto/parameterized_type.ex
+++ b/lib/ecto/parameterized_type.ex
@@ -64,6 +64,13 @@ defmodule Ecto.ParameterizedType do
         field :bar, MyApp.MyType, opt1: :baz, opt2: :boo
       end
 
+  To use this type in a schema field with a composite type, specify the type in a tuple
+  and opts afterwards.
+
+      schema "foo" do
+        field :bars, {:array, MyApp.MyType}, opt1: :baz, opt2: :boo
+      end
+
   To use this type in places where you need it to be initialized (for example,
   schemaless changesets), you can use `init/2`.