On 20 January 2015 at 09:25, Javix <s.camb...@gmail.com> wrote: > > > 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> 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 ?
I think just user.reload would do it. It is not something I have had to do often, why would one build an association and then want to throw it away again in the same action? Colin -- 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/CAL%3D0gLuKYgPTUCfE%2Bjk_QgVqpZ0jzSTXW86muGMempYVBY%3DO8g%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
