Rails Activerecord-链接关联以查询是否存在

Question

Say I have the models Lists, People, Outfit.

Lists have many people, people have many lists and one outfit. What is the most efficient way of checking if an outfit attribute 'name' exists in a given list with active-record?

I would like this to return as a boolean if possible

Answer 1

As long as you have these associations on your models ( people in Outfit model and lists in Person model) and I got what you are asking this one should work for me

Outfit.joins(people: :lists).exists?(lists: {id: your_list_id}, name: 'your_outfit_name')

and it's just one SQL query

In alternative, you could just have

Outfit.joins(:lists).exists?(lists: {id: your_list_id}, name: 'your_outfit_name')

and an association like

has_many :lists, through: :people

This is the idea but I find hard try this kind of stuff