How can I do a LEFT OUTER JOIN using Rails ActiveRecord?

Question

I don\'t have any ideas. Could you give me any clues (like reference sites). Any help will be appreciated.

Model1: GROUP         


        

Answer 1

I believe an includes will use a LEFT OUTER JOIN query if you do a condition on the table that the includes association uses:

Group.includes(:user_group_cmb).where(user_group_cmbs: { user_id: 1 })