Rails - Oct 2005 - Finding all parents of acts_as_tree relationship

I''m using acts_as_tree to maintain a hierarchy of categories (each
top-level category can contain multiple categories and each
sub-category can contain multiple sub-categories, etc.).

I want to be able to find all parents of a particular category.  I
realize that I can use @category.parent or even
@category.parent.parent to move up in the hierarchy, but I need this
to happen dynamically within the view because the hierarchy of each
category may be different.

Any ideas on how to handle this?

Thanks,

-Jason
 jasongilstrap-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Jason Gilstrap wrote:
> I''m using acts_as_tree to maintain a hierarchy of categories (each
> top-level category can contain multiple categories and each
> sub-category can contain multiple sub-categories, etc.).
> 
> I want to be able to find all parents of a particular category.  I
> realize that I can use @category.parent or even
> @category.parent.parent to move up in the hierarchy, but I need this
> to happen dynamically within the view because the hierarchy of each
> category may be different.
> 
> Any ideas on how to handle this?
Untested, but:

<% current = @category
while parent = current.parent %>
<%= render_parent parent %>
<%	current = parent
end %>

should do the trick...

-- 
Alex

As soon as you want to retrieve ALL parents or children of a tree, you
should  model your data as nested set rather than parent-child, so that
you can do it in one swoop of SQL instead of hitting the DB with one
request per generation.

See act_as_tree:
http://api.rubyonrails.org/classes/ActiveRecord/Acts/NestedSet/ClassMethods.html

There''s no direct method for all the parents, but it''s as
simple as

SELECT PARENT.* WHERE CHILD.LEFT IS BETWEEN PARENT.LEFT AND PARENT.RIGHT


Xavier

Jason Gilstrap wrote:
> I''m using acts_as_tree to maintain a hierarchy of categories (each
> top-level category can contain multiple categories and each
> sub-category can contain multiple sub-categories, etc.).
> 
> I want to be able to find all parents of a particular category.  I
> realize that I can use  <at> category.parent or even
>  <at> category.parent.parent to move up in the hierarchy, but I need
this
> to happen dynamically within the view because the hierarchy of each
> category may be different.
> 
> Any ideas on how to handle this?

Hi,

2005/10/20, Xavier Priour <xavier@priour.com>:
> As soon as you want to retrieve ALL parents or children of a tree, you
> should  model your data as nested set rather than parent-child, so that
> you can do it in one swoop of SQL instead of hitting the DB with one
> request per generation.
Aren't there all kinds of problems with acts_as_nested_set ?  I seem
to remember a recent thread on problems with it.  I know I myself
tried to use it at some point, but decided not to because I couldn't
get it to work reliably.  I can't remember what the problems were,
unfortunately.

Bye,
François

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