CODEWITHSUNDEEP
ruby-on-railspostgresqlactiverecord
kevcha
kevcha

Reputation: 1012

Applying conditions on has_many relationship

I'm having trouble retrieving some data from a Postgre database with rails 4.1.8

Let's considere two models with a has_many relationship

class Post < ActiveRecord::Base
  has_many :comments
end

and

class Comment < ActiveRecord::Base
  belongs_to :post
end

Comments have a state with approved or censured

I want to write a method in Post model self.all_comments_approved

I cannot figure out how to get only posts with all comments approved. I would like to write something like this (not working example) :

def sef.all_comments_approved
  joins(:comments).where("ALL(comments.state = 'approved')").references(:comments)
end

Thanks in advance for any help :)

Upvotes: 3

Views: 62

Answers (1)

BroiSatse
BroiSatse

Reputation: 44675

You might try using joins with group and having statement, but relation you would get would be very fragile (you wouldn't be able to query it any further as easily as you wish - pluck would destroy it completely etc).

Way around this issue is to split it into two db calls:

def self.all_comments_approved
  non_approved_ids = joins(:comments).where.not(comments: {state: 'approved'}).uniq.pluck(:id)
  where.not(id: non_approved_ids)
end

Upvotes: 1

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