Rails 唯一性：true model 带有带有 has_many 引用的数据库 - Ruby on Rails

Question

I have a problem. I need to set a model of report_templates unique in my database in relation to the classroom , each classroom has only one report_template . But in my DB, I already have a classroom with multiple report_templates .

is it safe to add this validation to report_template model upload to staging?

Answer 1

There are two approaches:-

1. If you add validation then you will get error when you are editing existing report templates. This is because validations are called when you save the record. So you might have to remove the duplicate/multiple records manually via console or db or a rake task. Simply accessing the record will not throw an error.

2. If one classroom has only report template do you think it is better to use either of below? I do not know the exact scenario so cannot suggest an approach.

• has_one association
• belongs_to association

Thank you.