Merge pull request #12621 from laurocaetano/fix_has_one_association_with_primary_key_set

Save association when primary key is manually set

Conflicts:
	activerecord/CHANGELOG.md

activerecord/CHANGELOG.md

+*   Save `has_one` association when primary key is manually set.
+
+    Fixes #12302.
+
+    *Lauro Caetano*
+
 *    Allow any version of BCrypt when using `has_secury_password`.
 
      *Mike Perham*

activerecord/lib/active_record/autosave_association.rb

@@ -384,7 +384,8 @@ def save_has_one_association(reflection)
             record.destroy
           else
             key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
-            if autosave != false && (new_record? || record.new_record? || record[reflection.foreign_key] != key || autosave)
+            if autosave != false && (autosave || new_record? || record_changed?(reflection, record, key))
+
               unless reflection.through_reflection
                 record[reflection.foreign_key] = key
               end
@@ -397,6 +398,11 @@ def save_has_one_association(reflection)
         end
       end
 
+      # If the record is new or it has changed, returns true.
+      def record_changed?(reflection, record, key)
+        record.new_record? || record[reflection.foreign_key] != key || record.attribute_changed?(reflection.foreign_key)
+      end
+
       # Saves the associated record if it's new or <tt>:autosave</tt> is enabled.
       #
       # In addition, it will destroy the association if it was marked for destruction.

activerecord/test/cases/associations/has_one_associations_test.rb

@@ -524,4 +524,15 @@ def test_has_one_assignment_triggers_save_on_change
     assert_equal 'new name', pirate.ship.reload.name
   end
 
+  def test_has_one_autosave_with_primary_key_manually_set
+    post = Post.create(id: 1234, title: "Some title", body: 'Some content')
+    author = Author.new(id: 33, name: 'Hank Moody')
+
+    author.post = post
+    author.save
+    author.reload
+
+    assert_not_nil author.post
+    assert_equal author.post, post
+  end
 end