Ruby finding all objects where has_one relation is true and is in array

Question

I am currently trying to implement a has_one relationship where you are able to search through all of blogs active posts. My problem comes where even though i explicitly search through the active_post relation it will return everything in its posts instead and not just the active ones which is what i want.

# == Schema Information
#
# Table name: blog
#
#  id              :integer          not null, primary key
#  name            :string(200)
#  context         :string(20)
#  show_on_summary :boolean
#

class Blog < ApplicationRecord
  has_many :posts, dependent: :destroy, autosave: true
  has_one :active_post, -> { order('created_at DESC').where(posts: { status_code: 'active' }) }, class_name: 'Post', foreign_key: :blog_id

# == Schema Information
#
# Table name: posts
#
#  id                   :integer          not null, primary key
#  created_at           :datetime         not null
#  updated_at           :datetime         not null
#  status_code          :string(20)
#  blog_id              :integer
#

class Post < ApplicationRecord
  STATUS_CODES = %w(active pending deactivated)
  belongs_to :blog

and yet when i run the code below where i have a list of posts of any type of status_code and am trying to find the blog where only their active_post relation matches, it will return every blog that has a post in that list regardless of status_code.

Blog.where(active_post: list_of_posts)

When i am debugging i can go to the individual blogs and look at their 'active_post' relation and it will show the correct latest active post. if there is no active post it will return nil which is what i want.

Answer 1

I don't think you can do it without manually joining your table

Blog.joins(:active_post).where(posts: { id: list_of_posts })

When you join your table, you ensure that the relation is going to be used, and specifying the "posts"."id" column also ensures that it won't use a subquery to match the Blogs ids

Answer 2

I think you don't need to specify the :posts table in the where clause:

class Blog < ApplicationRecord
  has_many :posts, dependent: :destroy, autosave: true
  has_one :active_post, -> { order('created_at DESC').where(status_code: 'active') }, class_name: 'Post', foreign_key: :blog_id
#...
end


Blog.first.active_post
# => return the latest post