Merge PR #43517

rails · Nov 25, 2021 · 38cb561 · 38cb561
1 parent 35983b1
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diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Ignore persisted in-memory records when merging target lists.
+
+    *Kevin Sjöberg*
+
 *   Fix regression bug that caused ignoring additional conditions for preloading has_many-through relations.
 
     Fixes #43132

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
@@ -340,7 +340,7 @@ def merge_target_lists(persisted, memory)
             end
           end
 
-          persisted + memory
+          persisted + memory.reject(&:persisted?)
         end
 
         def _create_record(attributes, raise = false, &block)

diff --git a/activerecord/test/cases/associations_test.rb b/activerecord/test/cases/associations_test.rb
@@ -282,6 +282,16 @@ def test_reset_unloads_target
     assert_not_predicate david.posts, :loaded?
     assert_not_predicate david.posts, :loaded
   end
+
+  def test_target_merging_ignores_persisted_in_memory_records
+    david = authors(:david)
+    assert david.thinking_posts.include?(posts(:thinking))
+
+    david.thinking_posts.create!(title: "Something else entirely", body: "Does not matter.")
+
+    assert_equal 1, david.thinking_posts.size
+    assert_equal 1, david.thinking_posts.to_a.size
+  end
 end
 
 class OverridingAssociationsTest < ActiveRecord::TestCase