Rails 按 has

本文介绍了Rails 按 has_many 关联的结果计数排序的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

无论如何我可以通过从子模型(Jobs)返回的项目数对结果(ASC/DESC)进行排序?

Is there anyway I can order the results (ASC/DESC) by number of items returned from the child model (Jobs)?

@featured_companies = Company.joins(:jobs).group(Job.arel_table[:company_id]).order(Job.arel_table[:company_id].count).limit(10)

例如:我需要将职位最高的公司打印在顶部

For example: I need to print the Companies with highest jobs on top

推荐答案

如果你希望经常使用这个查询，我建议你使用内置的 counter_cache

If you expect to use this query frequently, I suggest you to use built-in counter_cache

# Job Model class Job < ActiveRecord::Base belongs_to :company, counter_cache: true # ... end # add a migration add_column :company, :jobs_count, :integer, default: 0 # Company model class Company < ActiveRecord::Base scope :featured, order('jobs_count DESC') # ... end

然后像这样使用

@featured_company = Company.featured