Re: [SQLObject] How to store attributes of relationships?

[Ian B. <ia...@co...>]

On Sun, 2003-06-01 at 01:46, Edmund Lian wrote:
> Now the problem is that relationships have attributes too. For example, 
> we might want to store the date relationship started, intensity, etc. 
> These are attributes of the relationship, not of Person or Dog.
> 
> In traditional schema, this would be stored in the mapping table, or 
> some table that is related to the mapping table. How do we deal with 
> this in SQLObject?

It looks like you got this resolved, and that's probably the right
resolution as well.  After the next release I'm going to beef up the
join stuff a bit more, and it will be possible to add extra values to
the join.  So you might do (in my as-yet-imaginary extension):

class Person(SQLObject):
    dogs = ExtensibleRelatedJoin('Dog', extraColumn='times_per_day')

class Dog(SQLObject):
    people = ExtensibleRelatedJoin('Person', 
                 extraColumn='times_per_day')

d = Dog.new()
p = Person.new()
d.addPerson(p, 1) # p walks d once per day
p2 = Person.new()
d.addPerson(p2, 3) # p2 walks d three times per day (lots of walking)
d.people
>>> [(<Person 1>, 1), (<Person 2>, 3)]
p.dogs
>>> [(<Dog 1>, 1)]


If the relationship starts getting more complicted, than full SQLObject
classes for the relation table are probably called for.

  Ian