Apply scope to association subqueries

activerecord/CHANGELOG.md

@@ -1,3 +1,21 @@
+*   Apply scope to association subqueries. (belongs_to/has_one/has_many)
+
+    Given: `has_many :welcome_posts, -> { where(title: "welcome") }`
+
+    Before:
+    ```ruby
+    Author.where(welcome_posts: Post.all)
+    #=> SELECT (...) WHERE "authors"."id" IN (SELECT "posts"."author_id" FROM "posts")
+    ```
+
+    Later:
+    ```ruby
+    Author.where(welcome_posts: Post.all)
+    #=> SELECT (...) WHERE "authors"."id" IN (SELECT "posts"."author_id" FROM "posts" WHERE "posts"."title" = 'welcome')
+    ```
+
+    *Lázaro Nixon*
+
 *   Added PostgreSQL migration commands for enum rename, add value, and rename value.
 
     `rename_enum` and `rename_enum_value` are reversible. Due to Postgres

activerecord/lib/active_record/relation/predicate_builder/association_query_value.rb

@@ -26,6 +26,7 @@ def ids
           case value
           when Relation
             relation = value
+            relation = relation.merge(scope) if scope
             relation = relation.select(primary_key) if select_clause?
             relation = relation.where(primary_type => polymorphic_name) if polymorphic_clause?
             relation
@@ -48,6 +49,10 @@ def polymorphic_name
           associated_table.polymorphic_name_association
         end
 
+        def scope
+          associated_table.scope
+        end
+
         def select_clause?
           value.select_values.empty?
         end

activerecord/lib/active_record/table_metadata.rb

@@ -2,7 +2,7 @@
 
 module ActiveRecord
   class TableMetadata # :nodoc:
-    delegate :join_primary_key, :join_primary_type, :join_foreign_key, :join_foreign_type, to: :reflection
+    delegate :join_primary_key, :join_primary_type, :join_foreign_key, :join_foreign_type, :scope, to: :reflection
 
     def initialize(klass, arel_table, reflection = nil)
       @klass = klass

activerecord/test/cases/relation/where_test.rb

@@ -463,6 +463,12 @@ def test_where_on_association_with_collection_polymorphic_relation
       assert_equal [treasures(:diamond)], treasures
     end
 
+    def test_where_on_association_with_scoped_relation
+      authors = Author.where(welcome_posts: Post.all)
+      assert_equal 1, authors.count
+      assert_equal authors(:david), authors.first
+    end
+
     def test_where_with_strong_parameters
       author = authors(:david)
       params = ProtectedParams.new(name: author.name)