Rails - Feb 2006 - How do you display nested elements in their hierarchy?

Hello;

I''d like some pointers on how to display nested items in their 
hierarchy. I''m developing a project that uses habtm (as opposed to
"acts
as tree"). I can interact with the elements using "parent",
"child" etc.
fine. I just can''t figure out how to make the elements *display* in 
their relationships.

For example, if Ruby on Rails is a child of Server-Side and a sibling to 
PHP, and Server-side is a child of Coding and a sibling to Application, 
and Coding is a child of Main, how do I get the contents of the database 
to display in a browser something like:
Main
   Coding
      Server-Side
          Ruby on Rails
          PHP
      Application

If I sort the database by parent_id, I get stuff grouped by parent_id, 
not organized in the hierarchy. In some other scripting environment I 
would probably write some recursive routine but don''t know how to 
approach it with Rails.

Any tips or pointers would be appreciated. Even what terms to use in 
google - I''m getting bird-related sites when I search for
"nested"!

Thanks

-- 
Posted via http://www.ruby-forum.com/.

Steve-

	Here is a helper method I use with acts_as_tree to display a set of  
nested <ul>''s. If you have the parent and children methods
working
then this should work for you as well. Make sure to set up a counter  
cache for your model that you use this on, otherwise you will end up  
calling tons of COUNT sql queries as you recurse  through the children.

module ApplicationHelper
   def find_all_children(parent)
     if parent.children.size > 0
       ret = ''<ul>''
       parent.children.each { |child|
         if child.children.size > 0
           ret += ''<li>''
           ret += link_to "#{child.role}: #{child.last_name}, # 
{child.first_name} : #{child.login}",
                          :controller => ''review'', :action
=>
''boss_view'', :id => child
           ret += find_all_children(child)
           ret += ''</li>''
         else
           ret += ''<li>''
           ret += link_to "#{child.role}: #{child.last_name}, # 
{child.first_name} : #{child.login}",
                          :controller => ''review'', :action
=>
''boss_view'', :id => child
           ret += ''</li>''
         end
         }
       ret += ''</ul>''
     end
   end
end


This will build and return a nested list just like you want. Make  
whatever changes to the model names and attributes you need.

Cheers-
-Ezra


On Feb 1, 2006, at 7:21 AM, Steve Nelson wrote:
> Hello;
>
> I''d like some pointers on how to display nested items in their
> hierarchy. I''m developing a project that uses habtm (as opposed to
> "acts
> as tree"). I can interact with the elements using "parent",
"child"
> etc.
> fine. I just can''t figure out how to make the elements *display*
in
> their relationships.
>
> For example, if Ruby on Rails is a child of Server-Side and a  
> sibling to
> PHP, and Server-side is a child of Coding and a sibling to  
> Application,
> and Coding is a child of Main, how do I get the contents of the  
> database
> to display in a browser something like:
> Main
>    Coding
>       Server-Side
>           Ruby on Rails
>           PHP
>       Application
>
> If I sort the database by parent_id, I get stuff grouped by parent_id,
> not organized in the hierarchy. In some other scripting environment I
> would probably write some recursive routine but don''t know how to
> approach it with Rails.
>
> Any tips or pointers would be appreciated. Even what terms to use in
> google - I''m getting bird-related sites when I search for
"nested"!
>
> Thanks
>
> -- 
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
-Ezra Zygmuntowicz
WebMaster
Yakima Herald-Republic Newspaper
ezra@yakima-herald.com
509-577-7732

Ezra
Thank you very much for that. I appreciate your example of a recursive 
method in Rails.

I''ll see if I can get it to work. Thanks again!

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