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 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 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.leftnode.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 > (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 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
-~--~~~~--~~--~--~---
