From b900290f0d685141a43a6ab9c3ecb54c09787fa0 Mon Sep 17 00:00:00 2001
From: Zach Daniel <zach@zachdaniel.dev>
Date: Thu, 14 Sep 2023 22:36:23 -0400
Subject: [PATCH] docs: update custom type docs to handle nil values

---
 lib/ash/type/type.ex | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/ash/type/type.ex b/lib/ash/type/type.ex
index b49c6ee4..1fb5525e 100644
--- a/lib/ash/type/type.ex
+++ b/lib/ash/type/type.ex
@@ -86,7 +86,7 @@ defmodule Ash.Type do
   of `cast_input`, `cast_stored`, `dump_to_native` and `apply_constraints`, you can
   override how your type behaves as a collection. This is how the features of embedded
   resources are implemented. No need to implement them unless you wish to override the
-  default behaviour.
+  default behaviour. Your type is responsible for handling nil values in each callback as well.
 
   Simple example of a float custom type
 
@@ -98,16 +98,19 @@ defmodule Ash.Type do
     def storage_type(_), do: :float
 
     @impl Ash.Type
+    def cast_input(nil, _), do: {:ok, nil}
     def cast_input(value, _) do
       Ecto.Type.cast(:float, value)
     end
 
     @impl Ash.Type
+    def cast_stored(nil, _), do: {:ok, nil}
     def cast_stored(value, _) do
       Ecto.Type.load(:float, value)
     end
 
     @impl Ash.Type
+    def dump_to_native(nil, _), do: {:ok, nil}
     def dump_to_native(value, _) do
       Ecto.Type.dump(:float, value)
     end