Merge pull request #15309 from iantropov/issue_12698_build_through

Add setting of FK for throgh associations while building

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/cases/associations/has_many_through_associations_test.rb

1 files changed, 11 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/associations/through_association.rb b/activerecord/lib/active_record/associations/through_association.rb
index e47e81aa0f..09828dbd9b 100644
--- a/activerecord/lib/active_record/associations/through_association.rb
+++ b/activerecord/lib/active_record/associations/through_association.rb
@@ -91,6 +91,17 @@ module ActiveRecord
             raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)
           end
         end
+
+        def build_record(attributes)
+          inverse = source_reflection.inverse_of
+          target = through_association.target
+
+          if inverse && target && !target.is_a?(Array)
+            attributes[inverse.foreign_key] = target.id
+          end
+
+          super(attributes)
+        end
     end
   end
 end