Good catch. I will fix this asap.
On Jan 25, 6:36 pm, Bernd Rothert <roth...@googlemail.com> wrote:
> A table definition from the DAL chapter of the Web2py book:
>
> db.define_table('person',
> Field('uuid', length=64, default=uuid.uuid4()),
> Field('modified_on', 'datetime', default=now),
> Field('name'),
> format='%(name)s')
>
> "now" usually contains the current datetime from request.now and
> that's fine but the default for "uuid" would be identical for all
> inserts. Although the example doesn't use the default so it is not a
> problem there.
>
> If you omit the parenthesis behind "default=uuid.uuid4()" and simple
> pass the uuid4 function as the default it works as expected - the
> default is evaluated at insert time and yields a fresh uuid for each
> new record. I assume this is the intended behaviour although I
> couldn't find it documented(!?).
>
> Strangely replacing "default=now" in the same way with e.g.
> "default=datetime.datetime.now" does not work:
>
> now=datetime.datetime.now
> db.define_table('person',
> Field('uuid', length=64, default=uuid.uuid4),
> Field('modified_on', 'datetime', default=now),
> Field('name'),
> format='%(name)s')
>
> db.person.insert(name='Ernie')
> db.person.insert(name='Bert')
>
> db(db.person).select()
>
> >>> ValueError: invalid literal for int() with base 10: '<built'
>
> Umm,...
>
> db.executesql(db(db.person)._select())>>> [(1,
>
> u'b35cc052-3800-42a9-b7eb-bb9bc8ada271',
> u'<built-in method now of type object at 0x37c520>',
> u'Ernie'),
> (2,
> u'003ab438-f3aa-4474-8c24-b07d85406930',
> u'<built-in method now of type object at 0x37c520>',
> u'Bert')]
>
> (only works with Sqlite - MySQL would throw an error earlier)
>
> I think this check in BaseAdapter.represent (dal.py) is the culprit:
>
> def represent(self, obj, fieldtype):
> if type(obj) in (types.LambdaType, types.FunctionType):
> obj = obj()
>
> print type(datetime.datetime.now) in (types.LambdaType,
> types.FunctionType)
>
> >>> False
>
> This version lets you use any callable for generating "dynamic"
> default values (plus it's 3-4 times faster):
>
> def represent(self, obj, fieldtype):
> if callable(obj):
> obj = obj()
>
> I hope this doesn't cause any side effects - at least I could not find
> any (at this late/early hour)...
>
> Thanks
