fix: respect opts[:left_only?] argument passed to join_all_relationships

Author: zachdaniel

lib/join.ex

@@ -82,8 +82,7 @@ defmodule AshSql.Join do
         parent_query,
         no_inner_join?
       ) do
-    no_inner_join? =
-      no_inner_join? || query.__ash_bindings__.context[:data_layer][:no_inner_join?]
+    no_inner_join? = left_join_only?(query, opts, no_inner_join?)
 
     case join_parent_paths(query, filter, relationship_paths) do
       {:ok, query} ->
@@ -228,6 +227,12 @@ defmodule AshSql.Join do
     end
   end
 
+  @doc false
+  def left_join_only?(query, opts, explicit?) do
+    explicit? || query.__ash_bindings__.context[:data_layer][:no_inner_join?] ||
+      opts[:left_only?] || false
+  end
+
   @doc false
   def parent_expr(filter) do
     filter

test/join_test.exs

@@ -0,0 +1,35 @@
+# SPDX-FileCopyrightText: 2024 ash_sql contributors <https://github.com/ash-project/ash_sql/graphs/contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule AshSql.JoinTest do
+  use ExUnit.Case, async: true
+
+  alias AshSql.Join
+
+  defp query(data_layer_context \\ %{}) do
+    %{__ash_bindings__: %{context: %{data_layer: data_layer_context}}}
+  end
+
+  describe "left_join_only?/3" do
+    test "a select-context join is never inner joined" do
+      assert Join.left_join_only?(query(), [left_only?: true], false)
+    end
+
+    test "a filter-context join may still be inner joined" do
+      refute Join.left_join_only?(query(), [], false)
+    end
+
+    test "the data layer context can force left joins" do
+      assert Join.left_join_only?(query(%{no_inner_join?: true}), [], false)
+    end
+
+    test "an explicit no_inner_join? forces left joins" do
+      assert Join.left_join_only?(query(), [], true)
+    end
+
+    test "returns a boolean rather than nil" do
+      assert Join.left_join_only?(query(), [], false) == false
+    end
+  end
+end