CODEWITHSUNDEEP
ruby-on-railsactiverecord
dc10
dc10

Reputation: 2198

How to execute where condition on a joined table without querying the db in a loop

I have the following models

App has_many features
Feature has_many translations

Now I want to lookup a translation in order see to if I need to create or update.

    App.joins(features: :translations).first.features.each do |feature|
      languages.each do |lang|
        translation = feature.translations.where(language: lang).first_or_initialize
    end
   end

Now the problem is that I have a db lookup for each language which is quite a problem since I have a lot of features. How can I benefit from eager loading in order to just lookup the translation in the joined table?

Upvotes: 1

Views: 34

Answers (1)

moyinho20
moyinho20

Reputation: 624

Lets partition the languages into two two arrays, found and not_found:

 found, not_found = languages.partition do |lang| 
   App.joins(:features => :translations).where("translations.language" => lang).present?
 end

 found_language_translations = Translation.where("language in (?)", found)
 new_language_translations = not_found.map{|lang| Translation.new(language: lang) } #This will fire up too many queries though :/

Upvotes: 1

Related Questions