如何在 Ruby on Rails 中进行无外键连接？

Question

I am working with a very old Salesforce database, and need to make a query with a join without foreign keys using ActiveModels in Ruby on rails.

The app is modeling the salesforce into ActiveModels like this:

module Sf
  class Service < Sf::BaseRecord
    OBJECT_NAME = 'service__c'
    self.table_name = "salesforce.#{OBJECT_NAME}"
    self.primary_key = 'sfid'

    has_many :state_services, foreign_key: :service_id__c, dependent: nil

  end
end

I have a huge query that I need to write using ActiveModel.

salesforce.contentversion c 
JOIN salesforce.program__c pc 
JOIN salesforce.service__c sc 
    ON pc.legal_service_id__c = sc.sfid

I have Program and Service created. legal_service_id__c is not a key but sfid is.

How should I model this JOIN relationship into my models as the columns needed to the JOINs are not keys from each other?

Answer 1

There are multiple ways of going about this

1. Write the SQL query in string

sql = "Select * from ... your sql query here"
records_array = ActiveRecord::Base.connection.execute(sql)

2. Pass the JOIN clause as the string when using a join Eg. ContentVersion.all.joins("JOIN program__c pc ON pc.legal_service_id__c = content_versions.sfid")