[SQLObject] Joins/FKs with bad IDs

[Luke O. <lu...@me...>]

Hi -

Interface question for everyone to ponder:

If you have a foreignKey column, or a join, and have an object with an invalid
ID in one of these slots, it will raise an SQLObjectNotFound exception when
you try to access any of these attributes. Which is cool and all, except that
this means that many attribute accesses need to be try/excepted, instead of
just the explicit creation of objects. For instance, the contrived simple
access:

# should be try/excepted anyways, and we do
ob = Person(12)
# these don't seem reasonable to do so
v = ob.roles
w = ob.phoneNumber

should be:

try:
  ob = Person(12)
except SQLObjectNotFound:
  fail()
try:
  v = ob.roles
except SQLObjectNotFound:
  v = []
try:
  w = ob.phoneNumber
except SQLObjectNotFound:
  w = None

Now, I'm not entirely convinced on the solution. Sometimes you want to know
that you've got bad data, other times you just want to be able to go on,
blindly ignoring the bad (so having SQLObject do the exception checking in
those cases would be cool). (Alternatively, as I'm sure Edmund will tell me,
my database should ensure integrity at all times. And he's probably right, but
this still concerns me. :)

So. Should SQLObject provide an option to transparently pass over bad
relationships? Perhaps at the class level, perhaps at the instance level
(creation argument or anytime flag?), or should this be rethought into a
stronger enforcement of relationships throughout?

(We've occasionally been having full interpreter hangs on these accesses, but I
haven't tracked it down, may be an odd Webware or Postgres interaction. It is
completely tangential to this idea, but if anyone else is experiencing hangs
instead of exceptions when accessing invalid join or FK attrs, I'd love to
hear about it to help track this down.)

Thanks for your thoughts,

- Luke