Rails order by results count of has_many association

by

Rails 5+

Support for left outer joins was introduced in Rails 5 so you can use an outer join instead of using counter_cache to do this. This way you’ll still keep the records that have 0 relationships:

Company
  .left_joins(:jobs)
  .group(:id)
  .order('COUNT(jobs.id) DESC')
  .limit(10)

The SQL equivalent of the query is this (got by calling .to_sql on it):

SELECT "companies".* FROM "companies" LEFT OUTER JOIN "jobs" ON "jobs"."company_id" = "companies"."id" GROUP BY "company"."id" ORDER BY COUNT(jobs.id) DESC

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