CODEWITHSUNDEEP
mysqlruby-on-railsrubyactiverecord
user3775217
user3775217

Reputation: 4803

Rails 5 - Activerecord association query

I have two models associated with each other as follows.

class Comment < ApplicationRecord 
    belongs_to :user
end

class User < ActiveRecord::Base
    has_many :comments
end

Following record query 

comments_list = Comment.where(:post_id => post_id, :is_delete => false).joins(:user).select('comments.*,users.*')

Generates the following mysql query in logger

SELECT comments.*,users.* FROM `comments` INNER JOIN `users` ON `users`.`id` = `comments`.`user_id` WHERE `comments`.`post_id` = '81' AND `comments`.`is_delete` = 0.

This seems generating very ligitimate query, but comments_list object contain columns only from comments table.

Thanks

Upvotes: 0

Views: 309

Answers (1)

Marcelo Risoli
Marcelo Risoli

Reputation: 802

It depends on what you want to do, if you want to display the username next to the comment, Mert B.'s answer is fine, all you have to do is include(:user) and the users from the comment list will be fetched along when you do something like this:

comments_list = Comment.where(:post_id => post_id, :is_delete => false).joins(:user).select('comments.*,users.*')
comments_list.each do |comment|
  puts "#{comment.text} by #{comment.user.name}"
end

Or maybe if you want only users who have at least one comment, you can always select users from the user_ids on the comments table:

User.where(id: Comment.select(:user_id))

Upvotes: 1

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