On Tuesday, 20 January 2015 10:15:17 UTC+1, Colin Law wrote: > > On 20 January 2015 at 09:04, Javix <s.ca...@gmail.com <javascript:>> > wrote: > > I wonder id it is normal behaviour that when building an assosiation > 'build' > > method , the returned size of association array changes despite the > objet is > > nt saved yet ? Here is a short exampe to illustrate that: > > > > class User < ActiveRecord::Base > > has_many :posts, dependent: :destroy > > end > > > > class Post < ActiveRecord::Base > > belongs_to :user > > end > > > > Nothing complex until now. When I play with that in the console: > > Loading development environment (Rails 4.2.0) > > irb(main):001:0> user = User.first > > User Load (0.0ms) SELECT "users".* FROM "users" ORDER BY > "users"."id" > > ASC LIMIT 1 > > => #<User id: 1, name: "toto", created_at: "2015-01-16 11:18:41", > > updated_at: "2015-01-16 11:18:41"> > > irb(main):002:0> user.posts.size > > (0.0ms) SELECT COUNT(*) FROM "posts" WHERE "posts"."user_id" = ? > > [["user_id", 1]] > > => 0 > > irb(main):003:0> post = user.posts.build(title: 'ruby') > > => #<Post id: nil, user_id: 1, title: "ruby", created_at: nil, > updated_at: > > nil> > > irb(main):004:0> user.posts.size > > => 1 > > irb(main):005:0> > > > > As you see the size of user posts is changed by 1. Why ? The post is not > > still saved to the database. The user_id is nil. I had to apply some > > validation before adding a new post tp ths user, that's why I wonder if > it > > is normal adn how to display just the existing User posts without using > > 'select' for example. > > You have not saved it to the database but you have added it to the > users posts in memory. If you reload user it will revert to 0, and > you will lose the built post. If you want to check what it is in the > database then fetch the user to a new variable. > user1 = User.first > then user1.posts.size will be 0 > > Colin >
So it is normal because AR does not make a new query to the DB and operates on the existing cached collection. What if instead of making the same query to find the same user: user1 = User.first I'll do like that: user.posts(force_reload: true).size it works as needed and it seems like force_reload is false by default. What do you think ? -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-talk@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/654ebb5e-290a-4ddc-bc63-0fb35732576f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
