ActiveRecordでgroupクエリの結果の件数をスマートに取得したいだけ。 SELECT COUNT(*) FROM ( SELECT "users"."id" FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."id" GROUP BY "users"."id" HAVING (count(1) > 5) ) 前提: count vs size vs length ActiveRecord length vs size vs count でググる…
