Rails where has_many not empty

Question

My Campaign model has_many Response.

What I'd like to do is a search that's like Campaign.where.not(responses.nil?)

Basically returning a list of all campaigns that have responses.

What's the best way to do this?

Answer 1

You may do it by query with join:

Campaign.joins(:responses)

Or by two queries without join:

Campaign.where(id: Response.pluck(:campaign_id))