How to join only one record from a related table with Rails?

Question

In my rails application, I have two tables

Member
id
name
phone

Membership
id
duration
start_date
member_id

I'm trying to generate a query to join members with memberships but I only want the current membership which is the one with the most recent start_date for each member to be joined.

I came up with this

Member.joins(:memberships).merge(Membership.order(start_date: :desc).distinct(:member_id))

But it doesn't work and errors out with the message "(Object doesn't support #inspect)". Struggling with this, would really appreciate some help! Thank you :)

user_4479867 · Answer

I don't fully understand why you need this, but maybe you wanted something like this:

class Member < ApplicationRecord
  has_one :current_membership, 
          class_name: 'Membership', 
          -> { order(start_date: :desc) }
end

Member.joins(:current_membership)

doc: https://apidock.com/rails/ActiveRecord/Associations/ClassMethods/has_one

How to join only one record from a related table with Rails?

1 Answers