Massimo, Thanks very much for your quick response and helpful code.
I'm new to Web2Py, but I'm really enjoying it so far. In a way, it reminds me of the rapid development positive feedback loop I felt when I first encountered Borland's Delphi environment. Addictively fun! I'm not sure what's involved in packaging the code better, but I'll give it a shot as soon as i figure it out :) Thanks again! Chris On Feb 13, 8:27 am, mdipierro <mdipie...@cs.depaul.edu> wrote: > Chris, you manage to package this a little better please let me know. > You could write an alterego entry about it or just post the code > somewhere. > > Massimo > > On Feb 13, 10:24 am, mdipierro <mdipie...@cs.depaul.edu> wrote: > > > Hi Chris, > > > no. But it is trivial with web2py. > > > Here I implemented the example > > inhttp://www.sitepoint.com/print/hierarchical-data-database/ > > > db=SQLDB('sqlite://tree.db') > > db.define_table('tree',db.Field('title'),db.Field > > ('left','integer'),db.Field('right','integer')) > > db.tree.insert(title='Food',left=1,right=2) > > > def add_node(title,parent_title): > > > """ > > add_node > > ('Fruit','Food') > > add_node > > ('Meat','Food') > > add_node > > ('Red','Fruit') > > """ > > parent=db(db.tree.title==parent_title).select()[0] > > db(db.tree.right>=parent.right).update(right=db.tree.right+2) > > db(db.tree.left>=parent.right).update(left=db.tree.left+2) > > db.tree.insert(title=title,left=parent.right,right=parent.right+1) > > > def ancestors(title,*fields): > > """ print ancestors('Red',db.tree.title)""" > > node=db(db.tree.title==title).select()[0] > > return db(db.tree.left<node.left)(db.tree.right>node.right).select > > (orderby=db.tree.left,*fields) > > > def descendants(title,*fields): > > """ print ancestors('Fruit',db.tree.title)""" > > node=db(db.tree.title==title).select()[0] > > return db(db.tree.left>node.left)(db.tree.right<node.right).select > > (orderby=db.tree.left,*fields) > > > def test(): > > print db().select(db.tree.ALL) > > add_node('Fruit','Food') > > print db().select(db.tree.ALL) > > add_node('Meat','Food') > > print db().select(db.tree.ALL) > > add_node('Red','Fruit') > > print db().select(db.tree.ALL) > > print ancestors('Red',db.tree.title) > > print descendants('Fruit',db.tree.title) > > > test() > > > OUTPUT: > > tree.id,tree.title,tree.left,tree.right > > 1,Food,1,2 > > > tree.id,tree.title,tree.left,tree.right > > 1,Food,1,4 > > 2,Fruit,2,3 > > > tree.id,tree.title,tree.left,tree.right > > 1,Food,1,6 > > 2,Fruit,2,3 > > 3,Meat,4,5 > > > tree.id,tree.title,tree.left,tree.right > > 1,Food,1,8 > > 2,Fruit,2,5 > > 3,Meat,6,7 > > 4,Red,3,4 > > > tree.title > > Food > > Fruit > > > tree.title > > Red > > > On Feb 13, 2:31 am, sociotech <cfassna...@gmail.com> wrote: > > > > Just wondering if anyone has implemented modified preorder tree > > > traversal (MPTT) functions for Web2Py yet. MPTT is an efficient > > > approach to organizing hierarchically-related records (e.g., nested > > > menus, parent/child relationships, etc.) in a database. > > > > I was hoping someone here might've already implemented it (there is an > > > implementation for Django and more general information > > > here:http://code.google.com/p/django-mptt/), but I haven't found anything > > > yet. > > > > Thanks very much, > > > > Chris --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py Web Framework" group. To post to this group, send email to web2py@googlegroups.com To unsubscribe from this group, send email to web2py+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
