[Rails] To RForum devs: Writing a reusable NestedSet implementation

[Sascha Ebach]

Hi Rick,


thanks for your reply. Now I see why I should have paid more attention 
to graph theory ;)

Surely, any form of tree traversal is bound to have performance problems 
at one point in time if the tree really starts to fill up. But I guess 
this will be the case for any content repository technique. If you want 
to read more about the implementation I meant, here are my sources:

http://threebit.net/tutorials/nestedset/tutorial1.html
http://cvs.php.net/co.php/pear/DB_NestedSet/NestedSet.php?r=1.86
http://www.sitepoint.com/print/hierarchical-data-database
http://www.evolt.org/article/Four_ways_to_work_with_hierarchical_data/17/4047/index.html
http://www.intelligententerprise.com/001020/celko.jhtml?_requestid=745072
http://www.intelligententerprise.com/001020/celko1_2.jhtml

Celko is surely the most influential source (in the database field). I 
don't have his book yet (SQL for Smarties), but I will probably order it 
soon. He gives the example which is usually referred to by everybody else.

What I want to do is quite simply duplicate and rubyfy the code of the 
DB_NestedSet php implementation. I think that a lot of "content 
management" projects (for example RForum) could benefit from this if it 
was really easy to use such a library.

The technique you mention could be implemented later. (Maybe once I 
actually understand it ;) For the beginning it would be nice to have an 
interface for reading and writing nodes. The developer shouldn't really 
need to think about Trees and Nodes.

class Article < Contentnode
   def save: end
   def move; end
   def copy; end
   ... # do all the node and tree stuff in these methods automatically,
       # if possible
end

And then later just change the configuration

class NestedSet
   def use_implementation; 'graph' end
end

It would be great if something like this were possible. But for the 
beginning I would settle for less complex and more common solution I 
mentioned above.

Also very interesting is the Java Content Repository. It is a 
specification which tries to standardize the way content is accessed in 
an cms like application. Which is a good thing I guess since there is no 
standardization at all in this field.

Get the jsr170-0.12.pdf from the download here

http://www.jcp.org/aboutJava/communityprocess/review/jsr170/

The JCR specification talks more about the high level interface to 
access content rather than the implementation of the low level access 
techniques (where my interests lie right now). This API could be useful 
though since I think standardization is a good thing.

-- 
Sascha Ebach