# Help needed with acts\_as\_list **URL:** \ **Category:** Rails\ **Created:** [May 26, 2006, 12:21pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709 "2006-05-26T12:21:01Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 26, 2006, 12:21pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/1 "2006-05-26T12:21:01Z")
Hi ! There must be something I don’t understand clearly in acts\_as\_list I have a list of gallery entries (images + text), model is GalleryEntry. I have a field in\_exhibition (boolean) I want the list to be sorted with a scope on in\_exhibition : from 1 to N for every record having in\_exhibition = false and 1 to N for every record having in\_exhibition = true When I use acts\_as\_list :scope =\> “in\_exhibition = #{in\_exhibition}” I get a runtime error : undefined local variable or method `in\_exhibition’ for GalleryEntry:Class Is it possible to use acts\_as\_list that way ?? If not what is the solution ? Creating another model GalleryEntryType and : GalleryEntry belongs\_to :gallery\_entry\_type acts\_as\_list :scope =\> :gallery\_entry\_type ?? Any help appreciated I don’t know what’s wrong or right… thank you ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 26, 2006, 2:21pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/2 "2006-05-26T14:21:01Z")
Just do acts\_as\_list :scope =\> :in\_exhibition ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 26, 2006, 5:18pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/3 "2006-05-26T17:18:12Z")
Paul B. wrote: > Just do acts\_as\_list :scope =\> :in\_exhibition No, in that case RoR except a in\_exhibition\_id key field which handle the relation with a parent model. ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 26, 2006, 5:18pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/4 "2006-05-26T17:18:51Z")
Nuno wrote: > except Sorry, I mean expect ! ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 26, 2006, 6:49pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/5 "2006-05-26T18:49:53Z")
On 5/26/06, Nuno [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > acts\_as\_list :scope =\> :gallery\_entry\_type You need to surround your ‘scope’ clause with single-quotes, rather than double-quotes. It’s a little funny, because you don’t want Ruby to evaluate #{in\_exhibition} when it is first seen in the class body. You only want that to happen when the queries execute. acts\_as\_list :scope =\> ‘in\_exhibition = #{in\_exhibition}’ should work. ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 27, 2006, 9:43am UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/6 "2006-05-27T09:43:28Z")
Wilson B. wrote: > acts\_as\_list :scope =\> ‘in\_exhibition = #{in\_exhibition}’ > should work. It does ! Thanks ! Please, could you explain a little what’s happening behind the scene ? What is is the difference between the ‘’ and the “” version ? Thanks ---
**Author:** ![nuno](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/65b543/32.png) [@nuno](https://www.ruby-forum.com/u/nuno)\ **Post date:** [May 27, 2006, 11:49pm UTC](https://www.ruby-forum.com/t/help-needed-with-acts-as-list/61709/7 "2006-05-27T23:49:58Z")
On 5/27/06, Nuno [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Wilson B. wrote: > > > acts\_as\_list :scope =\> ‘in\_exhibition = #{in\_exhibition}’ > > should work. > > It does ! Thanks ! > > Please, could you explain a little what’s happening behind the scene ? > What is is the difference between the ‘’ and the “” version ? When Ruby sees a double-quoted string during execution, it immediately tries to ‘interpolate’ it. In this case, that would mean looking for a local variable or method called in\_exhibition, and inserting in\_exhibition.to\_s into the string. However, acts\_as\_list is a class method of ActiveRecord, and in\_exhibition is an INSTANCE method. When acts\_as\_list is executed, in\_exhibition is out of scope, and can’t be found. This makes sense, because what you’re saying is that the whole class acts\_as\_list, not just one instance of it. The single-quote trick is a workaround for that, because it lets acts\_as\_list wait until later to hunt up the value of in\_exhibition. Fairly weird, and personally I’d prefer the :scope option to work the same way as “validates\_uniqueness\_of” e.g. acts\_as\_list :scope =\> [:some\_column, :some\_other\_column] Until someone writes a plugin for that, we’re stuck with the funny single-quoted string. You should also be able to write the above as: acts\_as\_list :scope =\> %q[in\_exhibition = #{in\_exhibition}] …if that ever makes it easier.