It should be clarified that this occurs on the mysql backend, but not the postgres backend. It has to do with how MySQL handles the DATETIME object. You can't add a timedelta, because it expects a double.
I created a test app using a mysql backend and a Article model with created and updated datetime fields. created = 2010-10-15 09:13:02 updated = 2010-10-15 09:18:43 select created - updated from article_article +-------------------+ | updated - created | +-------------------+ | 541.000000 | +-------------------+ It's using the YYYYMMDDHHMMSS format of the datetime fields: 20101015091843 - 20101015091302 = 541 The delta isn't constant either, here are two sets of times that are 5 minutes apart: created=2010-10-15 09:00:00, updated=2010-10-15 09:05:00 mysql: select created - updated yiels 500 created=2010-10-15:09:59:00, updated=2010-10-15 10:04:00 mysql: select created - updated yields 4500 I haven't looked at the django mysql backend code, but based on this that warning is fatal in your case because it's definitely not doing what you want. And I don't see how you could write your query filter in its current format so that it is postgres/mysql agnostic On Fri, Oct 15, 2010 at 7:01 AM, Marc Aymerich <glicer...@gmail.com> wrote: > This is a fork of this tread: > http://groups.google.com/group/django-users/browse_thread/thread/5c6beb41fcf961a4 > I'm getting troubles combining instances of F() and timedelta. I'm working > with the very last trunk revision (14232), > I create a very simple model for troubleshoting the problem, the model is: > class dates(models.Model): > date1 = models.DateField(auto_now_add=True) > date2 = models.DateField() > And this is what I'm try to do: >>>> from test.dates.dates import dates >>>> from django.db.models import F >>>> import datetime >>>> >>>> dates.objects.filter(date1__gte=F('date2')+datetime.timedelta(minutes=3)) > Traceback (most recent call last): > File "<console>", line 1, in <module> > File "/usr/lib/python2.6/dist-packages/django/db/models/query.py", line > 67, in __repr__ > data = list(self[:REPR_OUTPUT_SIZE + 1]) > File "/usr/lib/python2.6/dist-packages/django/db/models/query.py", line > 82, in __len__ > self._result_cache.extend(list(self._iter)) > File "/usr/lib/python2.6/dist-packages/django/db/models/query.py", line > 268, in iterator > for row in compiler.results_iter(): > File "/usr/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", > line 675, in results_iter > for rows in self.execute_sql(MULTI): > File "/usr/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", > line 730, in execute_sql > cursor.execute(sql, params) > File "/usr/lib/python2.6/dist-packages/django/db/backends/util.py", line > 18, in execute > return self.cursor.execute(sql, params) > File "/usr/lib/python2.6/dist-packages/django/db/backends/mysql/base.py", > line 86, in execute > return self.cursor.execute(query, args) > File "/usr/lib/pymodules/python2.6/MySQLdb/cursors.py", line 168, in > execute > if not self._defer_warnings: self._warning_check() > File "/usr/lib/pymodules/python2.6/MySQLdb/cursors.py", line 82, in > _warning_check > warn(w[-1], self.Warning, 3) > Warning: Truncated incorrect DOUBLE value: '0 0:3:0' > > On the parent > thread http://groups.google.com/group/django-users/browse_thread/thread/5c6beb41fcf961a4 Alec > reports that this works on their django installation. > More over this pice of django code make use of > it: http://code.djangoproject.com/attachment/ticket/10154/dateexpressions.diff > Is this really a bug? it should be reported to django "bug tracker"? > -- > Marc > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-us...@googlegroups.com. > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
