Merge pull request rails#51517 from Shopify/composite-foreign-key-should-set-query-constraints-option

Ensure association's `foreign_key:` and `query_constraints:` options …

Author: eileencodes

activerecord/lib/active_record/reflection.rb

@@ -516,6 +516,10 @@ def initialize(name, scope, options, active_record)
         @foreign_key = nil
         @association_foreign_key = nil
         @association_primary_key = nil
+        # If the foreign key is an array, set query constraints options and don't use the foreign key
+        if options[:foreign_key].is_a?(Array)
+          options[:query_constraints] = options.delete(:foreign_key)
+        end
 
         ensure_option_not_given_as_class!(:class_name)
       end

activerecord/test/cases/associations/inverse_associations_test.rb

@@ -227,6 +227,20 @@ def test_polymorphic_has_one_should_find_inverse_automatically
 
     assert_predicate human_reflection, :has_inverse?
   end
+
+  def test_has_many_inverse_of_derived_automatically_despite_of_composite_foreign_key
+    car_review_reflection = Cpk::Car.reflect_on_association(:car_reviews)
+
+    assert_predicate car_review_reflection, :has_inverse?
+    assert_equal Cpk::CarReview.reflect_on_association(:car), car_review_reflection.inverse_of
+  end
+
+  def test_belongs_to_inverse_of_derived_automatically_despite_of_composite_foreign_key
+    car_reflection = Cpk::CarReview.reflect_on_association(:car)
+
+    assert_predicate car_reflection, :has_inverse?
+    assert_equal Cpk::Car.reflect_on_association(:car_reviews), car_reflection.inverse_of
+  end
 end
 
 class InverseAssociationTests < ActiveRecord::TestCase

activerecord/test/models/cpk/car.rb

@@ -3,5 +3,7 @@
 module Cpk
   class Car < ActiveRecord::Base
     self.table_name = :cpk_cars
+
+    has_many :car_reviews, foreign_key: [:car_make, :car_model]
   end
 end