Betternestedset talk - Dec 2006 - Exciting(?) changes to BetterNestedSet

Hi Everyone,

For about a year I have wanted to write a nested set implementation
that was as easy to use as acts_as_tree. Using BetterNestedSet I''ve
taken my first shot at that. The idea is fairly simple: the model
belongs_to :parent and has_many :children, and an after_save callback
takes care of updating the left/right values. You can still use
move_to_child_of, but you don''t need to:

    s = Set.new
    s.children.create # adds a child and saves it
    s.children << Set.new # add another child
    s.save # the child is saved to the database

    s2 = Set.new
    s.parent= s2
    s.save

    s2.parent.create

The tree would now look like this, and all the left/right values would
be correct:

root
  s2
    s
      child1
      child2

All of the other has_many and belongs_to methods are available as
well, such as #children.delete(child), #children = [c1, ...], etc.

This version of BetterNestedSet currently exists as a branch, so if
you want to play with it:
    script/plugin install
svn://rubyforge.org/var/svn/betternestedset/branches/ez-set

I''m quite curious to hear what everyone thinks of this. It is pretty
well tested, but could certainly use some real-world exposure. FYI, it
does not have any of the deprecated methods. I haven''t updated the
documentation yet.

The trunk line of BetterNestedSet has been active as well. Aside from
bug fixes, here''s a summary of the externally visible changes
I''ve
made since mid-November:

- Renamed #children_count to #all_children_count (the old name was
both misleading, inconsistent with other methods, and inconsistent
with acts_as_tree)

- Changed #move_to_child_of so it inserts children on the right.

- Added class method #sql_for, wich generates an SQL fragment for use in queries

- Documentation overhaul.

- Made all left/right altering methods concurrency-safe by using
transactions, calling object.reload, and by overriding ActiveRecord''s
#update.

- Fixed STI problem
(http://opensource.symetrie.com/trac/better_nested_set/ticket/10)

- Added scope enforcement for the move_to* methods (to prevent moving
nodes between different trees).

- Added methods to return or count leaf nodes (terminal children).

- Added methods to re-index trees (for converting standard trees to
nested sets, or repairing corrupted lft/rgt indexes).

- Lots and lots of tests.


Cheers,
Krishna

Krishna,
  This looks like a excellent continuation of the great work that you
have been doing with better_nested_sets.  I was curious if this new
branch would become a fork(ez-set), or if it would become the next
version of better_nested_sets ?

--Nick

I would favor merging the changes into trunk at some point, but only
if JCM and others agree. Right now it is just a new approach for
people to test and think about.

k

On 12/30/06, Nick Pavlica <linicks at gmail.com>
wrote:
> Krishna,
>   This looks like a excellent continuation of the great work that you
> have been doing with better_nested_sets.  I was curious if this new
> branch would become a fork(ez-set), or if it would become the next
> version of better_nested_sets ?
>
> --Nick
> _______________________________________________
> Betternestedset-talk mailing list
> Betternestedset-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/betternestedset-talk
>

Hi Krishna,

Le 29 d?c. 06, ? 21:12, Krishna Dole a ?crit :
> For about a year I have wanted to write a nested set implementation
> that was as easy to use as acts_as_tree. Using BetterNestedSet
I''ve
> taken my first shot at that. The idea is fairly simple: the model
> belongs_to :parent and has_many :children, and an after_save callback
> takes care of updating the left/right values. You can still use
> move_to_child_of, but you don''t need to:
>
>     s = Set.new
>     s.children.create # adds a child and saves it
>     s.children << Set.new # add another child
>     s.save # the child is saved to the database
>
>     s2 = Set.new
>     s.parent= s2
>     s.save
>
>     s2.parent.create
>
> The tree would now look like this, and all the left/right values would
> be correct
Great work.
I''d like to see benchmarks though, since using associations could be 
slower, don''t you think ?

Jean-Christophe Michel
--
symetrie.com

Better Nested Set for rails:
http://opensource.symetrie.com/trac/better_nested_set

Hi Jean-Christophe,
> I''d like to see benchmarks though, since using associations could
be
> slower, don''t you think ?
I''m pretty sure it is slower, but only (I think) on update.
Benchmarking is on my to-do list, once I get the callback problem and
some other things sorted out.

Krishna