字符串轉換爲在數量where子句

Question

我有以下where子句：

OnlineCourseRegistration.where(course_class_id: 6, status: "Completed") 
=> #<OnlineCourseRegistration id: 142, cart_id: 150, user_id: 7069, course_class_id: 681, created_at: "2017-07-15 22:06:06", updated_at: "2017-07-20 23:59:01", exam_attempts: 1, exam_completed_at: "2017-07-20 23:57:32", evaluation_completed_at: "2017-07-20 23:59:01", status: "Completed", score: "87", add_extension: false, retest_cart_id: nil, retest_purchased_at: nil> 

我還想補充一點，比分會是大於70，所以像...

OnlineCourseRegistration.where(course_class_id: 681, status: "Completed", :score.to_i > 70).last 

...但當然，這是行不通的。在where子句中有沒有辦法做到這一點？

Answer 1

ActiveRecord的地方接受string作爲查詢構造

OnlineCourseRegistration.where("course_class_id = ? AND status = ? AND score > ?", 681, "Completed", 70).last 

Answer 2

如果你不喜歡使用原始SQL可以使用阿雷爾方法，例如：

OnlineCourseRegistration.where(course_class_id: 681, status: "Completed").where(OnlineCourseRegistration.arel_table[:score].gt(70)).last 

Answer 3

爲後人我想補充這些cast solutions作爲答案也是：

where("score::int >= ?", 80)   # PostgreSQL-specific casting syntax 
where("cast(score as int) >= ?", 80) # Standard SQL type cast