[英]Rails Join With Association and Count
所以我有以下...
我想要的是列出具有相关提供者数量的大学,但提供者还需要一个地址。
我尝试过的
@universities = University.joins(:providers).select('universities.id, universities.name, universities.slug, providers.id, count(providers.id) as count').group('universities.id').order('count').reverse
提供如下列表:
- id: 14
name: Salus University
slug: salus-university
count: 72
- id: 22
name: University of Florida
slug: university-of-florida
count: 45
问题是计数包括没有地址的提供程序。 所以我尝试了以下方法:
@universities = University.joins(providers: :addresses).select('universities.id, universities.name, universities.slug, providers.id, count(providers.id) as count').group('universities.id').order('count').reverse
但是,这给了我地址总数的计数,而不是地址提供者的计数:
- id: 14
name: Salus University
slug: salus-university
count: 90
- id: 22
name: University of Florida
slug: university-of-florida
count: 60
好的,我终于弄清楚了。 我只是加入了职位,并增加了distinct
的数量:
@universities = University.joins(providers: :positions).select('universities.id, universities.name, universities.slug, providers.id, count(distinct providers.id) as count').group('universities.id').order('count desc')
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.