# Losing sanity, please help! **URL:** \ **Category:** Rails\ **Created:** [April 30, 2007, 2:43am UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254 "2007-04-30T02:43:53Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Dmitry\_Y](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/c67d28/32.png) [@Dmitry\_Y](https://www.ruby-forum.com/u/Dmitry_Y)\ **Post date:** [April 30, 2007, 2:43am UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254/1 "2007-04-30T02:43:53Z")
OK, I’m still trying to move a pic between albums, but this time I’m going totally ballistic. Please see the debugger session below. The model is simple, class Pic acts\_as\_list and belongs\_to :album. Can someone please please please explain to me why @old\_alb changes its value after line 73 ? ######### debugger session: [64, 73] in ./script/…/config/…/app/controllers/pic\_controller.rb 64 redirect\_to :action=\>:list and return 65 end 66 Debugger.start 67 debugger 68 =\> 69 @old\_alb=@pic.album 70 if @pic.update\_attributes(params[:pic]) 71 @pic.set\_tags @params[:tags] 72 @pic.album =Album.find(params[:album][:id]) 73 @pic.save (rdb:90) n ./script/…/config/…/app/controllers/pic\_controller.rb:70 if @pic.update\_attributes(params[:pic]) (rdb:90) p @old\_alb.id 2 (rdb:90) n ./script/…/config/…/app/controllers/pic\_controller.rb:71 @pic.set\_tags @params[:tags] (rdb:90) n ./script/…/config/…/app/controllers/pic\_controller.rb:72 @pic.album =Album.find(params[:album][:id]) (rdb:90) n ./script/…/config/…/app/controllers/pic\_controller.rb:73 @pic.save (rdb:90) n ./script/…/config/…/app/controllers/pic\_controller.rb:74 if @old\_alb != @pic.album (rdb:90) p @old\_alb.id 1 ######### end debugging session TIA, sleepless somewhere. ---
**Author:** ![Dmitry\_Y](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/c67d28/32.png) [@Dmitry\_Y](https://www.ruby-forum.com/u/Dmitry_Y)\ **Post date:** [April 30, 2007, 10:09am UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254/2 "2007-04-30T10:09:16Z")
Variables in Ruby are just references to an Object. So if you do a = b and change b, you change the object b refers to. As a refers tothe same object, the value of a will change too. Solution _should_ be (just looked this up, didn’t try and never had this problem myself before): a = b.dup ---
**Author:** ![Dmitry\_Y](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/c67d28/32.png) [@Dmitry\_Y](https://www.ruby-forum.com/u/Dmitry_Y)\ **Post date:** [April 30, 2007, 11:06am UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254/3 "2007-04-30T11:06:19Z")
Thanks for your suggestion, but it doesn’t seem true to me, in a simple case below all works as expected: > > foo=Album.find 1 > > =\> #\“2007-04-25 > > 03:28:30”, “name”=\>“top album”, “text”=\>nil, “id”=\>“1”, > > “user\_id”=\>“1”, “parent\_id”=\>nil}\> > > > bar=foo > > =\> #\“2007-04-25 > > 03:28:30”, “name”=\>“top album”, “text”=\>nil, “id”=\>“1”, > > “user\_id”=\>“1”, “parent\_id”=\>nil}\> > > > foo=Album.find 2 > > =\> #\“2007-04-25 > > 03:45:25”, “name”=\>“п©я─п╬п╡п╣я─п╨п╟”, “text”=\>“п╡п╬я┌ я┌п╟п╨”, > > “id”=\>“2”, “user\_id”=\>“1”, “parent\_id”=\>“1”}\> > > > bar==foo > > =\> false So why might it work otherwise in my app? rgds, Dmitry ---
**Author:** ![Dmitry\_Y](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/c67d28/32.png) [@Dmitry\_Y](https://www.ruby-forum.com/u/Dmitry_Y)\ **Post date:** [April 30, 2007, 11:48am UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254/4 "2007-04-30T11:48:25Z")
Your example is different from your real problem: your problem: 1. A = Something 2. B = A 3. You CHANGE the OBJECT that A refers to. A ----- \ \_ Object (If you change B.album, the Object here is changed, and as A points to the same Object in memory, it has “changed” to / B ----- 4. As B points to the same object, B has “changed” too (or the object it refers to, accuratly spoken) In your example that you just posted, however, you do something different: 1. foo = Something 2)bar = foo 2. You set A to point to a NEW, DIFFERENT OBJECT (namely the one created by “Album.find 2” ) foo ------- \ \_ Object (now you don’t change the Object, but you create a new one, and make foo point to it) / bar ------- result: foo -------\> new Object bar -------\> old Object 1. bar points to the object created in 1) , foo points to the Object created in 3) See the difference in 3) ? in your real problem, you change the OBJECT that both variables point to. in your second example, you make “foo” POINT to a different, freshly created Object. just give the .dup method a try. and don’t be bothered by my usage of Caps, i just tried to emphasise the crucial differences 😉 ---
**Author:** ![Dmitry\_Y](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/c67d28/32.png) [@Dmitry\_Y](https://www.ruby-forum.com/u/Dmitry_Y)\ **Post date:** [April 30, 2007, 12:07pm UTC](https://www.ruby-forum.com/t/losing-sanity-please-help/93254/5 "2007-04-30T12:07:27Z")
Thorsten, you’re DA MAN! My sanity is restored, thanks!