# Acts\_as\_list with has\_and\_belongs\_to\_many **URL:** \ **Category:** Rails\ **Created:** [November 18, 2005, 10:12pm UTC](https://www.ruby-forum.com/t/acts-as-list-with-has-and-belongs-to-many/50073 "2005-11-18T22:12:24Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![petermichaux](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/46a35a/32.png) [@petermichaux](https://www.ruby-forum.com/u/petermichaux)\ **Post date:** [November 18, 2005, 10:12pm UTC](https://www.ruby-forum.com/t/acts-as-list-with-has-and-belongs-to-many/50073/1 "2005-11-18T22:12:24Z")
Hi, I found the problem below on the Rails wiki and have the very same problem. Can anyone suggest a solution that does not involve an extra object like on the wiki? Thanks, Peter From: [Peak Obsession](http://wiki.rubyonrails.com/rails/pages/HowtoUseActsAsList) I’m looking for a Howto that would explain how to use ActsAsList[http://wiki.rubyonrails.com/rails/pages/ActsAsList](http://wiki.rubyonrails.com/rails/pages/ActsAsList)where you have something like the following: Book - id - name Category - id - name books\_categories - book\_id - category\_id - position The position in the books\_categories table is relative to the category. Thus, under one category book A might be in position 4, while in another category it might be in position 1. ---
**Author:** ![petermichaux](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/46a35a/32.png) [@petermichaux](https://www.ruby-forum.com/u/petermichaux)\ **Post date:** [November 19, 2005, 12:01am UTC](https://www.ruby-forum.com/t/acts-as-list-with-has-and-belongs-to-many/50073/2 "2005-11-19T00:01:21Z")
Ok, I’ve searched everywhere trying to figure this one out… Mechanize (installed from gems) is trying to reference a function that it can’t find. I’m using: - Mechanize (install gem mechanize) - the newest Ruby / Rails versions. I’m getting this error: undefined method `add\_header’ for #\ I know that mechanize is doing something with some files from Ruby 1.9 and has a file that says this: # required due to the missing get\_fields method in Ruby 1.8.2 $LOAD\_PATH.unshift File.join(File.dirname( **FILE** ), “mechanize”, “net-overrides”) and that it has this file: /usr/local/lib/ruby/gems/1.8/gems/mechanize-0.3.1/lib/mechanize/net-override s/net/http.rb So, for some reason it would appear that mechanize can’t see the over-ridden function??? It had the same problem with the “get\_fields” function (which is in the same place, and is a thing the mechanize developer added since Ruby 1.8 doesn’t have the response.get\_fields function), but I got around that by adding a function: def get\_fields2(response,key) return nil unless response.header[key.downcase] response.header[key.downcase].dup end to /usr/local/lib/ruby/gems/1.8/gems/mechanize-0.3.1/lib/mechanize.rb and then changing the references to “response.get\_fields(…)” to “get\_fields2(response,…)” … But that approach doesn’t work for the add\_header function. Thanks for any help! -Greg Greg E. Chief Technical Officer Eyetools, Inc. (916) 792-4538 removed\_email\_address@domain.invalid [http://www.eyetools.com](http://www.eyetools.com) -----Original Message----- From: removed\_email\_address@domain.invalid [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)]On Behalf Of Peter M. Sent: Friday, November 18, 2005 1:10 PM To: removed\_email\_address@domain.invalid Subject: [Rails] acts\_as\_list with has\_and\_belongs\_to\_many Hi, I found the problem below on the Rails wiki and have the very same problem. Can anyone suggest a solution that does not involve an extra object like on the wiki? Thanks, Peter From: [Peak Obsession](http://wiki.rubyonrails.com/rails/pages/HowtoUseActsAsList) I’m looking for a Howto that would explain how to use ActsAsList where you have something like the following: Book - id - name Category - id - name books\_categories - book\_id - category\_id - position The position in the books\_categories table is relative to the category. Thus, under one category book A might be in position 4, while in another category it might be in position 1. ---
**Author:** ![petermichaux](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/46a35a/32.png) [@petermichaux](https://www.ruby-forum.com/u/petermichaux)\ **Post date:** [November 19, 2005, 1:53am UTC](https://www.ruby-forum.com/t/acts-as-list-with-has-and-belongs-to-many/50073/3 "2005-11-19T01:53:05Z")
Reading the Rails source for acts\_as\_list and the ActiveRecord base.rb, part of the problem seems to be that acts\_as\_list doesn’t now about model associations. Also it appears that sql update statements made with rails update\_all cannot have multiple tables. Is all of this true? Couldn’t we have something like the following with the conventional join table being included automatically? Class Book \< ActiveRecord::Base has\_and\_belongs\_to\_many :categories acts\_as\_list :include =\> :category, :scope =\> :category\_id end Thanks, Peter ---
**Author:** ![petermichaux](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/46a35a/32.png) [@petermichaux](https://www.ruby-forum.com/u/petermichaux)\ **Post date:** [November 24, 2005, 3:56am UTC](https://www.ruby-forum.com/t/acts-as-list-with-has-and-belongs-to-many/50073/4 "2005-11-24T03:56:09Z")
Peter M. \ writes: > Hi, > > I found the problem below on the Rails wiki and have the very same problem. > Can anyone suggest a solution that does not involve an extra object like > on the > wiki? > > Thanks, > Peter > > From: [Peak Obsession](http://wiki.rubyonrails.com/rails/pages/HowtoUseActsAsList) > > I’m looking for a Howto that would explain how to use ActsAsList where you > have something like the following: Hi, I just struggled through this myself, and came up with a temporary, but relatively simple solution: [http://wiki.rubyonrails.com/rails/pages/HowToUseActsAsListWithHasAndBelongsToMany](http://wiki.rubyonrails.com/rails/pages/HowToUseActsAsListWithHasAndBelongsToMany) I’m fairly new to rails and ruby, though not DBs & Web programming, so feel free to refine the technique where it could be made more elegant!