Rails - Aug 2005 - Finding by inclusion in nested set

Say I have tasks with a belongs_to association to categories where the 
later act as a nested set. Now I want to find all tasks belonging to a 
specific category (given as primary key) or any of its sub-categories.

SELECT tasks.*, tasks_category.name 
FROM
  categories AS nested_set_categories, tasks
LEFT OUTER JOIN 
  categories AS tasks_category
ON
  tasks_category.id = tasks.category_id
WHERE
  (parent.id = ?)
AND
  (tasks_category.lft BETWEEN nested_set_categories.lft AND 
nested_set_categories.rgt)

(The aliases in this snippets require a patch for ActiveRecord; see 
<http://dev.rubyonrails.org/ticket/1907>.)

Unless I''m mistaken, this kind of query is not currently supported by 
AR#find. Of course, I could write this SQL manually, but that''s not 
what I want. Therefore I intend to write a patch to enhance find. I''m 
not sure about the "user interface", however. My current best idea is

  Task.find(:all, :belongs_to => [:category, record_or_id])

Any suggestions?


Michael

-- 
Michael Schuerig                   The Fifth Rider of the Apocalypse
mailto:michael-q5aiKMLteq4b1SvskN2V4Q@public.gmane.org         is a programmer.
http://www.schuerig.de/michael/