# Authorization recipe help **URL:** \ **Category:** Rails\ **Created:** [February 19, 2008, 3:42am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498 "2008-02-19T03:42:02Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 3:42am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/1 "2008-02-19T03:42:02Z")
Hello all, I am following the rails recipe book for authorization and it works as written. I have created a controller that will be administrate accounts and want to show each user with all their roles. I can’t seem to get the roles to match up. This is my logic 1. query RolesUsers (passing in the userid) 2 get the name of the role from Roles passing in the role\_id received from step one my problem is that I see this when I puts the result of step one #\ I am still new to ruby and a little confused as to what I am seeing. it appears to be a class object, but from what I am use to seeing, it is missing the @ in front of role\_id and user\_id. I get an error if I do this, privs.role\_id any clue what is happening? Thanks -Juan ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 3:55am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/2 "2008-02-19T03:55:55Z")
Hi, Lets step from here : privs= RolesUsers.get\_roles(userid) what your “get\_roles(userid)” is going to RolesUsers Active Record or Model? if yes, can you paste here your def get\_roles(any), so we can understand well your problem. _~_~_~_~_~\*\*~_~_~_~_~_ Reinhart Ariando YM : Booking2Heaven WEB : [http://teapoci.blogspot.com](http://teapoci.blogspot.com) ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 4:06am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/3 "2008-02-19T04:06:39Z")
This is what I have, if there is a better way, I would be happy to see it. Thanks class RolesUsers \< ActiveRecord::Base def self.get\_roles(userid) find(:all, :conditions =\> [“user\_id = ?”, userid]) end end On Feb 18, 8:55 pm, Visit Indonesia 2008 \ **Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 5:12am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/4 "2008-02-19T05:12:24Z") it makes Perfect sense now!! thank you! On Feb 18, 9:27 pm, Visit Indonesia 2008 \ **Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 4:27am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/5 "2008-02-19T04:27:35Z") Hello, > class RolesUsers \< ActiveRecord::Base > def self.get\_roles(userid) > find(:all, :conditions =\> [“user\_id = ?”, userid]) > end You use find :all, so that the result of your searching will be formed as array. you can not run privs.role\_id. First let we count how many array is there using : @size = privs.size example you got 1 you execute like this privs[0].role\_id or to see all list of role\_id you can use like it: for kungfu in privs print kungfu.role\_id end remember the ways below looks like the same but having difference result : [First] @fighter = WorldFigther.find(1) and [Second] @fighter = WorldFigther.find(:all, :conditions =\> [“id = ?”, 1]) To get fighter name of the First is @fighter.name, but the second is @fighter[0].name I hope you can understand clearly, your problem is. _~_~_~_~_~\*\*~_~_~_~_~_ Reinhart Ariando YM : Booking2Heaven WEB : [http://teapoci.blogspot.com](http://teapoci.blogspot.com) ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 19, 2008, 4:31pm UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/6 "2008-02-19T16:31:54Z")
@Juan, You’re working your way into the infamous N+1 db problem… I believe that the recipe has a User model like this: class User has\_and\_belongs\_to\_may :roles … end To collect all the roles, you should rely on the association that you have defined: @current\_user = … (User.find(session[:userid] iirc) @roles = @current\_user.roles @roles.each do |role| puts role.name end ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 20, 2008, 5:15am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/7 "2008-02-20T05:15:09Z")
this is fantastic, could you explain what you mean by the infamous N+1 db problem? I will be the first to admit I am not well versed in db lingo, is this a performance measure? I would like to learn as much as possible from this mistake, so that I don’t repeat it in the future. thanks again for the help. -Juan ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 20, 2008, 9:42am UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/8 "2008-02-20T09:42:28Z")
What is the meaning of infamous N+1 db problem? sorry i am not good in db analyst and design. ---
**Author:** ![jvazquez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/858c86/32.png) [@jvazquez](https://www.ruby-forum.com/u/jvazquez)\ **Post date:** [February 20, 2008, 8:26pm UTC](https://www.ruby-forum.com/t/authorization-recipe-help/129498/9 "2008-02-20T20:26:54Z")
N+1… Assume the user has N roles. If you grab the user it will take 1 db round trip followed by N more to retrieve each of the roles for a total of N+1 round trips. db access is likely to be one of the most costly aspects of your application so you want to eliminate that as much as possible. Enter the has\_many :through =\> xxx and has\_and\_belongs\_to\_many (the latter is out of favor since the former permits you a full model that may contain extra state information about the join – like a subscription class that joins a customer to his periodical but also tells you whether the customer is paid up). If/when you have one of these specified you can access the associated models through the named association and Rails will automatically do a join for you. So… class User has\_many :user\_roles has\_many :roles, :through=\>:user\_roles … end user = User.find(…, :include=\>:roles) The above find will trigger a left outer join so that you collect the user and ALL of his associated roles in ONE db roundtrip. On Feb 20, 3:42 am, Visit Indonesia 2008 \