improvement: improve the behavior of defaults

functional defaults are added at action time, others are added directly
into the changeset

lib/ash/actions/create.ex

@@ -76,7 +76,7 @@ defmodule Ash.Actions.Create do
     else
       Ash.Changeset.for_create(changeset, action.name, %{}, actor: actor)
     end
-    |> Ash.Changeset.set_defaults(:create)
+    |> Ash.Changeset.set_defaults(:create, true)
     |> Ash.Changeset.cast_arguments(action)
   end
 

lib/ash/actions/update.ex

@@ -74,7 +74,7 @@ defmodule Ash.Actions.Update do
     else
       Ash.Changeset.for_update(changeset, action.name, %{}, actor: actor)
     end
-    |> Ash.Changeset.set_defaults(:update)
+    |> Ash.Changeset.set_defaults(:update, true)
     |> Ash.Changeset.cast_arguments(action)
   end
 

lib/ash/changeset/changeset.ex

@@ -280,11 +280,6 @@ defmodule Ash.Changeset do
     tenant: [
       type: :any,
       doc: "set the tenant on the changeset"
-    ],
-    defaults: [
-      type: :any,
-      doc:
-        "A list of attributes and arguments to apply defaults for. Defaults to: []. Any unset defaults are set when the action is called."
     ]
   ]
 
@@ -450,7 +445,7 @@ defmodule Ash.Changeset do
         |> validate_relationships_accepted(action)
         |> cast_arguments(action, opts[:defaults], true)
         |> run_action_changes(action, opts[:actor])
-        |> set_defaults(changeset.action_type, opts[:defaults] || [])
+        |> set_defaults(changeset.action_type, false)
         |> add_validations()
         |> require_values(changeset.action_type)
         |> mark_validated(action.name)
@@ -585,13 +580,16 @@ defmodule Ash.Changeset do
   end
 
   @doc false
-  def set_defaults(changeset, action_type, keys \\ :all)
+  def set_defaults(changeset, action_type, lazy? \\ false)
 
-  def set_defaults(changeset, :create, keys) do
+  def set_defaults(changeset, :create, lazy?) do
     changeset.resource
     |> Ash.Resource.Info.attributes()
     |> Enum.filter(&(not is_nil(&1.default)))
-    |> Enum.filter(&(keys == :all || &1.name in keys))
+    |> Enum.filter(fn attribute ->
+      lazy? or
+        not (is_function(attribute.default) or match?({_, _, _}, attribute.default))
+    end)
     |> Enum.reduce(changeset, fn attribute, changeset ->
       force_change_new_attribute_lazy(changeset, attribute.name, fn ->
         default(:create, attribute)
@@ -599,11 +597,14 @@ defmodule Ash.Changeset do
     end)
   end
 
-  def set_defaults(changeset, :update, keys) do
+  def set_defaults(changeset, :update, lazy?) do
     changeset.resource
     |> Ash.Resource.Info.attributes()
     |> Enum.filter(&(not is_nil(&1.update_default)))
-    |> Enum.filter(&(keys == :all || &1.name in keys))
+    |> Enum.filter(fn attribute ->
+      lazy? or
+        not (is_function(attribute.update_default) or match?({_, _, _}, attribute.update_default))
+    end)
     |> Enum.reduce(changeset, fn attribute, changeset ->
       force_change_new_attribute_lazy(changeset, attribute.name, fn ->
         default(:update, attribute)

lib/ash/query/query.ex

@@ -217,11 +217,6 @@ defmodule Ash.Query do
     tenant: [
       type: :any,
       doc: "set the tenant on the query"
-    ],
-    defaults: [
-      type: :any,
-      doc:
-        "A list of arguments to apply defaults for. Defaults to: []. Any unset defaults are set when the action is called."
     ]
   ]
 
@@ -257,7 +252,7 @@ defmodule Ash.Query do
       |> cast_params(action, args)
       |> run_preparations(action, opts[:actor])
       |> add_action_filters(action, opts[:actor])
-      |> cast_arguments(action, opts[:defaults], true)
+      |> cast_arguments(action, true)
     else
       add_error(query, :action, "No such action #{action_name}")
     end
@@ -801,23 +796,19 @@ defmodule Ash.Query do
   end
 
   @doc false
-  def cast_arguments(query, action, defaults \\ :all, only_supplied? \\ false) do
+  def cast_arguments(query, action, only_supplied? \\ false) do
     action.arguments
     |> Enum.reject(& &1.private?)
     |> Enum.reject(&(only_supplied? && match?({:ok, _}, fetch_argument(query, &1.name))))
     |> Enum.reduce(query, fn argument, new_query ->
-      {ignore_nil_check, value} =
-        if defaults == :all || argument.name in (defaults || []) do
-          {false, get_argument(query, argument.name) || argument_default(argument.default)}
-        else
       value = get_argument(query, argument.name)
 
+      {ignore_nil_check, value} =
         if argument_default(argument.default) do
           {true, value}
         else
           {false, value}
         end
-        end
 
       cond do
         !ignore_nil_check && is_nil(value) && !argument.allow_nil? ->

lib/ash/resource/attribute.ex

@@ -82,12 +82,12 @@ defmodule Ash.Resource.Attribute do
     update_default: [
       type: {:custom, Ash.OptionsHelpers, :default, []},
       doc:
-        "A zero argument function, an {mod, fun, args} triple or a value. If no value is provided for the attribute on update, this value is used."
+        "A zero argument function, an {mod, fun, args} triple or a value. `Ash.Changeset.for_update/4` sets the default in the changeset if a value is not provided."
     ],
     default: [
       type: {:custom, Ash.OptionsHelpers, :default, []},
       doc:
-        "A zero argument function, an {mod, fun, args} triple or a value. If no value is provided for the attribute on create, this value is used."
+        "A zero argument function, an {mod, fun, args} triple or a value. `Ash.Changeset.for_create/4` sets the default in the changeset if a value is not provided."
     ],
     description: [
       type: :string,
@@ -106,7 +106,10 @@ defmodule Ash.Resource.Attribute do
                            |> OptionsHelpers.set_default!(:writable?, false)
                            |> OptionsHelpers.set_default!(:private?, true)
                            |> OptionsHelpers.set_default!(:default, &DateTime.utc_now/0)
-                           |> OptionsHelpers.set_default!(:update_default, &DateTime.utc_now/0)
+                           |> OptionsHelpers.set_default!(
+                             :update_default,
+                             &DateTime.utc_now/0
+                           )
                            |> OptionsHelpers.set_default!(:type, Ash.Type.UtcDatetimeUsec)
                            |> OptionsHelpers.set_default!(:allow_nil?, false)