如果nested_attributes为空，则在Rails模型中隐藏记录

Question

I have two models in my Rails app: Listing and ListingPhoto . I want to set some kind of scope on my model that removes Listing s that have no nested ListingPhoto s. These are being pulled in from an external API, so I have no easy way to control these saving.

Listing looks like this:

class Listing < ActiveRecord::Base

  acts_as_taggable_on :listing_types

  has_many :listing_photos
  accepts_nested_attributes_for :listing_photos, allow_destroy: true

  private

end

ListingPhoto looks like this:

class ListingPhoto < ActiveRecord::Base
  belongs_to :listing
  validates :listing, presence: true
  mount_uploader :photo, PhotoUploader
end

What would I need to add to my Listing model to stop listings with empty photo sets showing up?

Answer 1

you can add static method in Listing model:

def self.with_photos
    includes(:listing_photos).where.not(:listing_photos => {:listing_id => nil})
end

and then just easily call:

Listing.with_photos