fix: honor reuse_values? when lazy loading relationships

lib/ash/actions/read/calculations.ex

@@ -1386,7 +1386,7 @@ defmodule Ash.Actions.Read.Calculations do
             nil ->
               related_query =
                 relationship.destination
-                |> Ash.Query.set_context(%{private: %{lazy?: true}})
+                |> Ash.Query.set_context(%{private: %{lazy?: true, reuse_values?: reuse_values?}})
                 |> Ash.Query.select([])
                 |> merge_query_load(
                   further,
@@ -1814,7 +1814,9 @@ defmodule Ash.Actions.Read.Calculations do
     Ash.Resource.loaded?(initial_data, relationship_path ++ [calculation], type: :request)
   end
 
-  defp loaded_and_reusable?(_initial_data, _relationship_path, _calculation, _false), do: false
+  defp loaded_and_reusable?(_initial_data, _relationship_path, _calculation, false) do
+    false
+  end
 
   defp add_calculation_dependency(query, source, dest) do
     %{

lib/ash/actions/read/read.ex

@@ -364,6 +364,7 @@ defmodule Ash.Actions.Read do
 
   defp load_relationships(data, query, opts) do
     lazy? = !!opts[:lazy?]
+    reuse_values? = !!opts[:reuse_values?]
 
     context =
       %{
@@ -384,15 +385,17 @@ defmodule Ash.Actions.Read do
             Ash.Actions.Read.Relationships.load(
               data,
               query,
-              lazy?
+              lazy?,
+              reuse_values?
             )
           end
 
         _ ->
           Ash.Actions.Read.Relationships.load(
             data,
             query,
-            lazy?
+            lazy?,
+            reuse_values?
           )
       end
     end

lib/ash/actions/read/relationships.ex

@@ -18,10 +18,10 @@ defmodule Ash.Actions.Read.Relationships do
     {:ok, records}
   end
 
-  def load(records, query, lazy?) do
+  def load(records, query, lazy?, reuse_values?) do
     query.load
     |> with_related_queries(query, records, lazy?)
-    |> fetch_related_records(records)
+    |> fetch_related_records(records, reuse_values?)
     |> attach_related_records(records)
   end
 
@@ -39,9 +39,9 @@ defmodule Ash.Actions.Read.Relationships do
     end)
   end
 
-  defp fetch_related_records(batch, records, acc \\ [])
+  defp fetch_related_records(batch, records, reuse_values?, acc \\ [])
 
-  defp fetch_related_records([], _records, acc) do
+  defp fetch_related_records([], _records, _reuse_values?, acc) do
     Enum.map(acc, fn
       {a, b, %Task{} = task} ->
         {a, b, Task.await(task, :infinity)}
@@ -54,12 +54,12 @@ defmodule Ash.Actions.Read.Relationships do
     end)
   end
 
-  defp fetch_related_records([first | rest], records, acc) do
+  defp fetch_related_records([first | rest], records, reuse_values?, acc) do
     result =
       case first do
         {relationship, {:lazy, query}} ->
           {relationship, {:lazy, query},
-           lazy_related_records(records, relationship, query, Enum.empty?(rest))}
+           lazy_related_records(records, relationship, query, Enum.empty?(rest), reuse_values?)}
 
         {relationship, %{valid?: true} = related_query} ->
           do_fetch_related_records(records, relationship, related_query, Enum.empty?(rest))
@@ -68,10 +68,10 @@ defmodule Ash.Actions.Read.Relationships do
           {relationship, related_query, {:error, errors}}
       end
 
-    fetch_related_records(rest, records, [result | acc])
+    fetch_related_records(rest, records, reuse_values?, [result | acc])
   end
 
-  defp lazy_related_records(records, relationship, related_query, last?) do
+  defp lazy_related_records(records, relationship, related_query, last?, reuse_values?) do
     primary_key = Ash.Resource.Info.primary_key(relationship.source)
 
     related_records_with_lazy_join_source =
@@ -101,6 +101,8 @@ defmodule Ash.Actions.Read.Relationships do
       fn ->
         Ash.load(related_records_with_lazy_join_source, related_query,
           lazy?: true,
+          reuse_values?:
+            reuse_values? || related_query.context[:private][:reuse_values?] || false,
           domain: related_query.domain,
           actor: related_query.context.private[:actor],
           tenant: related_query.tenant,

lib/ash/changeset/changeset.ex

@@ -4280,8 +4280,11 @@ defmodule Ash.Changeset do
     ],
     meta: [
       type: :any,
-      doc:
-        "Freeform data that will be retained along with the options, which can be used to track/manage the changes that are added to the `relationships` key."
+      doc: """
+      Freeform data that will be retained along with the options, which can be used to track/manage the changes
+      that are added to the `relationships` key. Use the `meta[:order]` option to specify the order in which multiple
+      calls to `manage_relationship` should be executed.
+      """
     ],
     ignore?: [
       type: :any,

test/support/policy_complex/resources/post.ex

@@ -1,5 +1,6 @@
 defmodule Ash.Test.Support.PolicyComplex.Post do
   @moduledoc false
+
   use Ash.Resource,
     domain: Ash.Test.Support.PolicyComplex.Domain,
     data_layer: Ash.DataLayer.Ets,
@@ -44,6 +45,7 @@ defmodule Ash.Test.Support.PolicyComplex.Post do
     end
 
     create :create do
+      primary? true
       accept [:text]
       change relate_actor(:author)
     end