Comments on: Rails: What’s the best way to handle my lists?

By: seasonfive

seasonfive — Fri, 04 May 2007 18:36:41 +0000

Last try ...

class Content < ActiveRecord::Base
  has_one     :picture, :as => :gallery 
end

class Picture < ActiveRecord::Base
  belongs_to  :gallery, :polymorphic => true 
end

By: seasonfive

seasonfive — Fri, 04 May 2007 18:35:33 +0000

Arghhh none of the class pasted well ... Sorry to poluate your blog man. I would be able to edit my post but i can't. Here the Content and Car model which could have Picture :

class Car  :gallery
  ....
end

class Content  :gallery 
  ....
end

By: seasonfive

seasonfive — Fri, 04 May 2007 18:34:06 +0000

Sorry for the double post but seems my Picture model wasn't pasted correctly :-p

class Picture  true  
  file_column :file, :magick => {
                        :versions => {  ...  }
    }
    
  acts_as_list  :scope => 'gallery_type = \'#{gallery_type}\' AND gallery_id = \'#{gallery_id}\' AND session = \'#{session}\''
  
end

(Hope this will work this time ...)

By: seasonfive

seasonfive — Fri, 04 May 2007 18:32:03 +0000

I had exactly the same problem. I used polymorphism which is a more generic way to manage than the Album solution (allow each entity to have one or severals picture without database modification) and that works well :

class Picture  true  
  file_column :file, :magick => {
                        :versions => { ...  }
    }
    
  acts_as_list  :scope => 'gallery_type = \'#{gallery_type}\' AND gallery_id = \'#{gallery_id}\''  
end

Then in the Content model :

class Content  :gallery 
  ...
end

and in the Car model :

class Car  :gallery
  ...
end

Hope this could help.

By: Bogdan

Bogdan — Thu, 24 Aug 2006 23:00:30 +0000

Nice solution Josh. Definitely more simplistic, more like CRUD.

(Sorry Josh, for the incomplete code, but it seems that the comment is somehow “escaped”)

By: Josh Knowles

Josh Knowles — Thu, 24 Aug 2006 20:05:42 +0000

While I like have the more explicit Domain Model myself, Bogdan’s solution is correct and may actually be simplier if you don’t need the concept of an Album object. See http://wiki.rubyonrails.org/rails/pages/SimplePolymorphicAssociation for some explanation of what a Polymorphic Association is.

You don’t even need the fancy scope that he is using, you can just get away with doing :scope => ‘addressable_id’

Josh

By: Jim

Jim — Thu, 24 Aug 2006 15:40:24 +0000

Thanks Bogdan! Your response is definitely interesting but I believe Josh’s method is the more ‘rails’ way to solve the situation.

By: Jim

Jim — Thu, 24 Aug 2006 15:37:49 +0000

Hey Josh,
Sorry for the confusion if the comments weren’t showing up! My comments are all moderated.. my site gets a lot of spam comments like over a dozen a day. Once you’ve been approved you are free to comment from that point onward.

By: Bogdan

Bogdan — Thu, 24 Aug 2006 11:31:07 +0000

With polymorphic associations..

class Project  :addressable
end

class Service  :addressable
end

class Image  true
    acts_as_list :scope => 
       '(addressable_id = #{addressable_id} AND addressable_type = "Project") OR (addressable_id = #{addressable_id} AND addressable_type = "Service")'
end

It is based on polymorphic relationships and this excerpt from the documentation: it's also possible to give it an entire string that is interpolated if you need a tighter scope than just a foreign key. Example: acts_as_list :scope => @todo_list_id = #{todo_list_id} AND completed = "". Hope it's useful. Haven't tested it though.

By: Josh Knowles

Josh Knowles — Thu, 24 Aug 2006 10:00:39 +0000

(note have attempted to add comment couple times but it isn't displaying all the code... too tired to figure out so I butchered it a bit trying to make it submit correctly, you should still get the general idea) It's late, heading to bed, figured I'd try and point you in right direction, not sure if this will make sense or work What if we change your domain model a tad... Instead of a Photo belonging to both Project or Service what if it belonged to an Album. You could then have a Project/Service belong_to an album (we use belong_to here so that the foreign key gets placed on the project table as opposed to having to have a project_id and service_id on each album). You then add an has_many :through to get direct access to the Photos. Example (note writing from memory check for typos/syntax errors):

class Photo 
  belongs_to :album
  acts_as_list :scope => :album
end

class Album
  has_many :photos
end

class Project
  belongs_to :album
  has_many :photos, :through => :album
end

class Service
  belongs_to :album
  has_many :photos, :through => :album
end