improvement: only_when_valid? on changes

fix: set storage_type to `:uuid` for Ash.Type.UUID

.formatter.exs

@@ -80,6 +80,7 @@ locals_without_parens = [
   name: 1,
   not_found_message: 1,
   on: 1,
+  only_when_valid?: 1,
   pagination: 1,
   parse_attribute: 1,
   prefix: 1,

lib/ash/changeset/changeset.ex

@@ -710,6 +710,9 @@ defmodule Ash.Changeset do
     changes = changes ++ Ash.Resource.Info.changes(changeset.resource, changeset.action_type)
 
     Enum.reduce(changes, changeset, fn
+      %{only_when_valid?: true}, %{valid?: false} = changeset ->
+        changeset
+
       %{change: {module, opts}}, changeset ->
         module.change(changeset, opts, %{actor: actor})
 

lib/ash/resource/change/change.ex

@@ -10,7 +10,7 @@ defmodule Ash.Resource.Change do
   when this change was configured on a resource, and the context, which currently only has
   the actor.
   """
-  defstruct [:change, :on]
+  defstruct [:change, :on, :only_when_valid?]
 
   @type t :: %__MODULE__{}
 
@@ -26,6 +26,15 @@ defmodule Ash.Resource.Change do
         Many validations don't make sense in the context of deletion, so by default it is left out of the list.
         """
       ],
+      only_when_valid?: [
+        type: :boolean,
+        default: false,
+        doc: """
+        If the change should only be run on valid changes. By default, all changes are run unless stated otherwise here.
+
+        For 2.0 this may become the default.
+        """
+      ],
       change: [
         type: {:ash_behaviour, Ash.Resource.Change, Ash.Resource.Change.Builtins},
         doc: """

lib/ash/type/type.ex

@@ -654,7 +654,7 @@ defmodule Ash.Type do
 
   # @callback equal?(term, term) :: boolean
 
-  defmacro __using__(_) do
+  defmacro __using__(_opts) do
     quote location: :keep do
       @behaviour Ash.Type
 

lib/ash/type/uuid.ex

@@ -8,7 +8,7 @@ defmodule Ash.Type.UUID do
   use Ash.Type
 
   @impl true
-  def storage_type, do: Ecto.UUID
+  def storage_type, do: :uuid
 
   @impl true
   def cast_input(value, _) when is_binary(value) do