Add support join types in where.associated method

activerecord/CHANGELOG.md

@@ -3,6 +3,16 @@
 
     *Jason Nochlin*
 
+*   Adds support to change join type in the `where.associated` method.
+    By default associated method use joins association, Support join type are joins, left_joins and left_outer_joins.
+
+    In this example change default join type to the `left_joins`
+    ```ruby
+    Post.where.associated(join_type: :left_joins, :author)
+    ```
+
+    *Saleh Alhaddad*
+
 *   Fix an issue where `ActiveRecord::Encryption` configurations are not ready before the loading
     of Active Record models, when an application is eager loaded. As a result, encrypted attributes
     could be misconfigured in some cases.

activerecord/lib/active_record/relation/query_methods.rb

@@ -72,10 +72,19 @@ def not(opts, *rest)
       #    # INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
       #    # INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"
       #    # WHERE "authors"."id" IS NOT NULL AND "comments"."id" IS NOT NULL
-      def associated(*associations)
+      #
+      # Additionally, you can change join type by one of the allowed types, joins, left_joins and left_outer_joins
+      # Example: Post.where.associated(join_type: :left_joins, :author)
+      #
+      def associated(*associations, join_type: :joins)
+        allowed_types = [:joins, :left_joins, :left_outer_joins]
+        unless allowed_types.include?(join_type.to_sym)
+          raise ArgumentError.new("An `#{join_type}` does not exist on the allowed association `#{allowed_types.join(', ')}`.")
+        end
+
         associations.each do |association|
           reflection = scope_association_reflection(association)
-          @scope.joins!(association)
+          @scope.send("#{join_type}!", association)
           if reflection.options[:class_name]
             self.not(association => { reflection.association_primary_key => nil })
           else

activerecord/test/cases/relation/where_chain_test.rb

@@ -92,6 +92,13 @@ def test_associated_with_enum_extended_late
       assert_equal Author.find(2), Author.order(id: :desc).joins(:reading_listing).where.associated(:reading_listing).extending(Author::NamedExtension).first
     end
 
+    def test_associated_with_change_join_type
+      Comment.where.associated(:children, join_type: :left_joins).tap do |relation|
+        assert_includes     relation, comments(:greetings)
+        assert_not_includes relation, comments(:more_greetings)
+      end
+    end
+
     def test_missing_with_association
       assert_predicate posts(:authorless).author, :blank?
       assert_equal [posts(:authorless)], Post.where.missing(:author).to_a