Merge pull request #47246 from Shopify/support-joins-for-assoc-with-c…

…omposite-foreign-key

Support joins for associations with composite foreign keys

activerecord/lib/active_record/reflection.rb

@@ -199,10 +199,14 @@ def join_scope(table, foreign_table, foreign_klass)
 
         scope_chain_items.inject(klass_scope, &:merge!)
 
-        primary_key = join_primary_key
-        foreign_key = join_foreign_key
+        primary_key_column_names = Array(join_primary_key)
+        foreign_key_column_names = Array(join_foreign_key)
 
-        klass_scope.where!(table[primary_key].eq(foreign_table[foreign_key]))
+        primary_foreign_key_pairs = primary_key_column_names.zip(foreign_key_column_names)
+
+        primary_foreign_key_pairs.each do |primary_key_column_name, foreign_key_column_name|
+          klass_scope.where!(table[primary_key_column_name].eq(foreign_table[foreign_key_column_name]))
+        end
 
         if klass.finder_needs_type_condition?
           klass_scope.where!(klass.send(:type_condition, table))

activerecord/test/cases/associations/inner_join_association_test.rb

@@ -10,10 +10,12 @@
 require "models/person"
 require "models/tagging"
 require "models/tag"
+require "models/sharded/blog_post"
+require "models/sharded/comment"
 
 class InnerJoinAssociationTest < ActiveRecord::TestCase
   fixtures :authors, :author_addresses, :essays, :posts, :comments, :categories, :categories_posts, :categorizations,
-           :taggings, :tags, :people
+           :taggings, :tags, :people, :sharded_comments, :sharded_blog_posts
 
   def test_construct_finder_sql_applies_aliases_tables_on_association_conditions
     result = Author.joins(:thinking_posts, :welcome_posts).first
@@ -212,4 +214,21 @@ def test_find_with_conditions_on_through_reflection
     assert_equal 0, categories.first.special_categorizations.size
     assert_equal 1, categories.second.special_categorizations.size
   end
+
+  test "joins a belongs_to association with a composite foreign key" do
+    first_post_comments = Sharded::Comment.joins(:blog_post).where(blog_post: { title: "My first post!" }).to_a
+    expected_blog_post = sharded_blog_posts(:great_blog_post_one)
+
+    assert_not_empty comments
+    assert_equal(expected_blog_post.comments.to_a.sort, first_post_comments.sort)
+  end
+
+  test "joins a has_many association with a composite foreign key" do
+    blog_posts = Sharded::BlogPost.joins(:comments).where(comments: { body: "Your first blog post is great!" }).to_a
+
+    expected_comment = sharded_comments(:unique_comment_blog_post_one)
+
+    assert_not_empty blog_posts
+    assert_equal(expected_comment.blog_post, blog_posts.first)
+  end
 end

activerecord/test/cases/associations_test.rb

@@ -131,7 +131,7 @@ def test_association_with_references
 
   def test_belongs_to_a_model_with_composite_foreign_key_finds_associated_record
     comment = sharded_comments(:great_comment_blog_post_one)
-    blog_post = sharded_blog_posts(:great_post_blog_one)
+    blog_post = sharded_blog_posts(:great_blog_post_one)
 
     assert_equal(blog_post, comment.blog_post)
   end
@@ -148,15 +148,15 @@ def test_belongs_to_a_model_with_composite_primary_key_uses_composite_pk_in_sql
   end
 
   def test_has_many_association_with_composite_foreign_key_loads_records
-    blog_post = sharded_blog_posts(:great_post_blog_one)
+    blog_post = sharded_blog_posts(:great_blog_post_one)
 
     comments = blog_post.comments.to_a
     assert_includes(comments, sharded_comments(:wow_comment_blog_post_one))
     assert_includes(comments, sharded_comments(:great_comment_blog_post_one))
   end
 
   def test_model_with_composite_query_constraints_has_many_association_sql
-    blog_post = sharded_blog_posts(:great_post_blog_one)
+    blog_post = sharded_blog_posts(:great_blog_post_one)
 
     sql = capture_sql do
       blog_post.comments.to_a
@@ -167,7 +167,7 @@ def test_model_with_composite_query_constraints_has_many_association_sql
   end
 
   def test_append_composite_foreign_key_has_many_association
-    blog_post = sharded_blog_posts(:great_post_blog_one)
+    blog_post = sharded_blog_posts(:great_blog_post_one)
     comment = Sharded::Comment.new(body: "Great post! :clap:")
     comment.save
     blog_post.comments << comment
@@ -206,7 +206,7 @@ def test_assign_composite_foreign_key_belongs_to_association
   end
 
   def test_append_composite_foreign_key_has_many_association_with_autosave
-    blog_post = sharded_blog_posts(:great_post_blog_one)
+    blog_post = sharded_blog_posts(:great_blog_post_one)
     comment = Sharded::Comment.new(body: "Great post! :clap:")
     blog_post.comments << comment
 

activerecord/test/fixtures/sharded_blog_posts.yml

@@ -1,10 +1,10 @@
 _fixture:
   model_class: Sharded::BlogPost
 
-great_post_blog_one:
+great_blog_post_one:
   title: "My first post!"
   blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_one) %>
 
-great_post_blog_two:
-  title: "My first post!"
+great_blog_post_two:
+  title: "My second post!"
   blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_two) %>

activerecord/test/fixtures/sharded_comments.yml

@@ -3,15 +3,20 @@ _fixture:
 
 great_comment_blog_post_one:
   body: "I really enjoyed the post!"
-  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_post_blog_one) %>
+  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_blog_post_one) %>
   blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_one) %>
 
 wow_comment_blog_post_one:
   body: "Wow!"
-  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_post_blog_one) %>
+  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_blog_post_one) %>
+  blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_one) %>
+
+unique_comment_blog_post_one:
+  body: "Your first blog post is great!"
+  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_blog_post_one) %>
   blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_one) %>
 
 great_comment_blog_post_two:
   body: "I really enjoyed the post!"
-  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_post_blog_two) %>
+  blog_post_id: <%= ActiveRecord::FixtureSet.identify(:great_blog_post_two) %>
   blog_id: <%= ActiveRecord::FixtureSet.identify(:sharded_blog_two) %>