ActiveRecord - querying polymorphic associations

Question

I am using polymorphic associations to track Comments in my project. All very straight forward stuff.

The problem I have is in querying based on the polymorphic asso

Answer 1

Rails does not include a polymorphic join by default but this gem would help you to joins your polymorphic relationship with ease. https://github.com/jameshuynh/polymorphic_join

Answer 2

Here is an example to adapt to your purpose.

class AdwordsCampaign < ApplicationRecord
  has_many :daily_campaign_reports, as: :ga_campaign
end

class DailyCampaignReport < ApplicationRecord

  belongs_to :ga_campaign, polymorphic: true

  # scope
  def self.joins_ga_campaign(model)
    models = model.to_s.pluralize
    sql = <<~SQL
      INNER JOIN #{models}
      ON #{models}.id = daily_campaign_reports.ga_campaign_id
    SQL
    joins(sql).where(ga_campaign_type: model.to_s.camelize)
  end
end

Then I can use it wherever needed like this:

DailyCampaignReport.joins_ga_campaign(:adwords_campaign)