On May 31, 2009, at 11:45 PM, Karen Tracey wrote: > On Sun, May 31, 2009 at 10:13 AM, Eric Abrahamsen <gir...@gmail.com> > wrote: > > Hi, > > I've got two models, Author and Entry, with a foreignkey from Entry to > Author. There are many Authors with no related entries, and until > recently I've been able to put this manager on the Author model to > only select Authors with Entries: > > def contributors(): > return self.exclude(entry__isnull=True) > > Recently this started returning a FieldError, saying it could not > resolve "entry" into a field. > > What changed? Did you update Django? Change your code? Something > must have changed, and if you could identify it, that would be a clue. > > I'm running the most recent version of > django. Before I go tearing up my app trying to figure out what I > changed, I'd like to make sure – is this the recommended way to check > for Authors with no Entries? I just found a couple of hints online > saying to expect errors from this kind of code, though it has worked > to date (and appears to still be working on some production code). > Should this work? > > Where are these hints to expect errors from this sort of code? In > the Django docs would be a reliable source (but I'd hope it would be > a lot clearer than a hint of possible errors), random blogs or old > mailing list threads not so much.
Thanks for the detailed response, Karen. I was just worried at first that isnull was an improper way of checking for Authors with no Entry (the hints came from this message [http://groups.google.com/group/django-users/msg/47ba69359ceace29 ] which I may have misinterpreted, the docs don't seem to reference this situation directly). But now I see that all filters using Entry are returning the same error, not just isnull, so it's definitely a problem in my code. I identified the commit in my own code that blew things up (thanks to my excellent version-tracking habits, it's a pretty large and tangled commit). This commit touches neither the Author nor the Entry model, it's got: Two new models, one called Sample with a ForeignKey to Author, one called TranslatorProfile with a OneToOneField to Author (no related names on either). ModelForms for both of these new models. I also moved two existing modelforms to a different place in the file. I'm putting the diff file into dpaste here: http://dpaste.com/49912/, in case anyone's got the patience to look at it. That's a diff between -r301, which works, and working copy, which doesn't. The whole models.py file (broken working copy) is here: http://dpaste.com/49913/ The only other possibly relevant thing I can think of is that Entries also have a ManyToMany to Authors. An Entry is written by an Author (the ForeignKey), but can also be "about" some unspecified number of Authors. The ManyToMany has a related name on it, the ForeignKey doesn't, but changing that doesn't fix the code, and besides it has been working fine like that up until now. Many thanks for any insight! Eric and, for the heck of it, the traceback: Traceback: File "/Library/Python/2.5/site-packages/django-trunk/django/core/ handlers/base.py" in get_response 92. response = callback(request, *callback_args, **callback_kwargs) File "/Library/Python/2.5/site-packages/django-trunk/django/utils/ decorators.py" in _wrapped_view 48. response = view_func(request, *args, **kwargs) File "/Users/eric/stuff/dbase/views.py" in contributors 128. conts = list(Author.objects.contributors()) File "/Users/eric/stuff/dbase/managers.py" in contributors 34. return self .select_related ("user").filter(is_contributor=True).exclude(entry__isnull=True) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ query.py" in exclude 474. return self._filter_or_exclude(True, *args, **kwargs) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ query.py" in _filter_or_exclude 483. clone.query.add_q(~Q(*args, **kwargs)) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ sql/query.py" in add_q 1610. self.add_q(child, used_aliases) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ sql/query.py" in add_q 1614. can_reuse=used_aliases) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ sql/query.py" in add_filter 1512. negate=negate, process_extras=process_extras) File "/Library/Python/2.5/site-packages/django-trunk/django/db/models/ sql/query.py" in setup_joins 1677. "Choices are: %s" % (name, ", ".join(names))) Exception Type: FieldError at /contributors/ Exception Value: Cannot resolve keyword 'entry' into field. Choices are: book, categories, characters, contact, cv, desc, desc_HTML, edit_date, email, gender, given_name, id, is_author, is_chinese, is_contributor, is_living, is_translator, links, location, photo, post_date, profession, rel_entries, sample, slug, surname, translatorprofile, user, webpage > > FWIW, I cannot recreate any problem like this using this manager & > models: > > class AManager(models.Manager): > def contributors(self): > return self.exclude(entry__isnull=True) > > class Author(models.Model): > name = models.CharField(max_length=44) > def __unicode__(self): > return self.name > objects = AManager() > > class Entry(models.Model): > value = models.CharField(max_length=23) > author = models.ForeignKey(Author) > def __unicode__(self): > return u'%s (author: %s)' % (self.value, unicode(self.author)) > > in a Python shell using Django SVN r10865: > > Python 2.5.2 (r252:60911, Oct 5 2008, 19:24:49) > [GCC 4.3.2] on linux2 > Type "help", "copyright", "credits" or "license" for more information. > (InteractiveConsole) > >>> from ttt.models import Author, Entry > >>> Author.objects.all() > [] > >>> Entry.objects.all() > [] > >>> Author.objects.contributors() > [] > >>> Author.objects.create(name="Jacinta") > <Author: Jacinta> > >>> Author.objects.create(name="Eamon") > <Author: Eamon> > >>> Author.objects.contributors() > [] > >>> Entry.objects.create(value="Icterus",author=Author.objects.all() > [1]) > <Entry: Icterus (author: Eamon)> > >>> Author.objects.contributors() > [<Author: Eamon>] > >>> quit() > > I think the models/manager I created match what you describe, so how > is you setup different? > > Karen > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@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 -~----------~----~----~----~------~----~------~--~---
