Rails - May 2007 - ActiveRecord Previous/Next Record

Does ActiveRecord offer a simple solution to get previous/next records
relative to a certain record? For instance, say I have this table:

PEOPLE
id | name
1  | john
2  | mary
3  | bob

Using p = Person.find(2), is it possible to get the previous (john)
and next (bob) records using perhaps something like p.previous and
p.next? If not, how can I do this without resorting to ugly queries?

Thanks in advance


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Try my acts_as_ordered plugin:

http://svn.viney.net.nz/things/rails/plugins/acts_as_ordered/

-Jonathan.

On 5/1/07, toulax-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<toulax-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Does ActiveRecord offer a simple solution to get previous/next records
> relative to a certain record? For instance, say I have this table:
>
> PEOPLE
> id | name
> 1  | john
> 2  | mary
> 3  | bob
>
> Using p = Person.find(2), is it possible to get the previous (john)
> and next (bob) records using perhaps something like p.previous and
> p.next? If not, how can I do this without resorting to ugly queries?
>
> Thanks in advance
>
>
> >
>
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Exactly what I needed, thanks!

On May 1, 6:44 am, "Jonathan Viney"
<jonathan.vi...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Try my acts_as_ordered plugin:
>
> http://svn.viney.net.nz/things/rails/plugins/acts_as_ordered/
>
> -Jonathan.
>
> On 5/1/07, tou...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<tou...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
>
> > Does ActiveRecord offer a simple solution to get previous/next records
> > relative to a certain record? For instance, say I have this table:
>
> > PEOPLE
> > id | name
> > 1  | john
> > 2  | mary
> > 3  | bob
>
> > Using p = Person.find(2), is it possible to get the previous (john)
> > and next (bob) records using perhaps something like p.previous and
> > p.next? If not, how can I do this without resorting to ugly queries?
>
> > Thanks in advance

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Toulax,

   > Using p = Person.find(2), is it possible to get the previous (john)
   > and next (bob) records using perhaps something like p.previous and
   > p.next? If not, how can I do this without resorting to ugly queries?


If you
 - only need next()
 - use MySql (optional)

simply add this in environment.rb :

   class ActiveRecord::Base
      def next
         self.class.find(:first, :conditions => [''id >
?'', self.id])
      end
   end

For non-MySql db, you might have to add

     :order => ''id asc''

to the query.

(see: http://weblog.jamisbuck.org/2007/4/6/faking-cursors-in-activerecord)


Alain Ravet
http://blog.ravet.com

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