[SQLObject] Table Joining to Itself

[David M. <da...@re...>]

Hi,

I'm posting here in the hope that my problem, and its solution, might 
save others from the battle I've had.

Basically, I'm implementing a web shopping cart. While I was tempted to 
have just a plain 2 or 3 level product hierarchy, this felt too 
restrictive and I wanted a more general solution - the ability to have 
an unrestricted n-level hierarchy of product categories.

After some experimenting and reading SQLObject source, the following 
solution came out:

   class prodcats(SQLObject):
       _connection = _conn
       name=StringCol()
       longname=StringCol()
       parent=ForeignKey('prodcats', default=None)
       children=MultipleJoin('prodcats', joinColumn='parent_id')

   prodcats.createTable()

   rPets = prodcats.new(
     name='pets', longname='Pets')

   rBirds = prodcats.new(
     name='birds', longname='Birds', parent=rPets)

   rLargeBirds = prodcats.new(
     name='large', longname='Large Birds', parent=rBirds)

   rSmallBirds = prodcats.new(
     name='small', longname='Small Birds', parent=rBirds)

   rDogs = prodcats.new(
     name='dogs', longname='Dogs', parent=rPets)

   rLargeDogs = prodcats.new(
     name='large', longname='Large Dogs', parent=rDogs)

   rSmallDogs = prodcats.new(
     name='small', longname='Small Dogs', parent=rDogs)

-- 

Kind regards
David

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