Infinite loop caused by ordering

[David Cramer]

The model itself contains no data in the database:

class Syntax(models.Model):
    name    = models.CharField(max_length=32)
    lexer   = models.CharField(max_length=32)
    order   = models.IntegerField(default=10)
    parent  = models.ForeignKey('self', blank=True, null=True)
    children= models.SmallIntegerField(default=0)

    class Meta:
        ordering = ('parent', 'order', 'name')

Traceback:
File "/Library/Python/2.5/site-packages/django/core/handlers/base.py" in get_response
  77.                     request.path_info)
File "/Library/Python/2.5/site-packages/django/core/urlresolvers.py" in resolve
  240.                     sub_match = pattern.resolve(new_path)
File "/Library/Python/2.5/site-packages/django/core/urlresolvers.py" in resolve
  240.                     sub_match = pattern.resolve(new_path)
File "/Library/Python/2.5/site-packages/django/core/urlresolvers.py" in resolve
  179.             return self.callback, args, kwargs
File "/Library/Python/2.5/site-packages/django/core/urlresolvers.py" in _get_callback
  185.             self._callback = get_callable(self._callback_str)
File "/Users/dcramer/Development/django-compositepks/django/utils/functional.py" in wrapper
  130.         result = func(*args)
File "/Library/Python/2.5/site-packages/django/core/urlresolvers.py" in get_callable
  54.                 lookup_view = getattr(__import__(mod_name, {}, {}, ['']), func_name)
File "/Users/dcramer/Development/pastethat/pastes/views.py" in <module>
  6. from forms import PasteFileForm, PasteLinkForm, PasteTextForm
File "/Users/dcramer/Development/pastethat/pastes/forms.py" in <module>
  55. class PasteTextForm(forms.Form):
File "/Users/dcramer/Development/pastethat/pastes/forms.py" in PasteTextForm
  56.     syntax  = GroupedModelChoiceField(queryset=Syntax.objects.all(), empty_label='(Automatic)', required=False)
File "/Library/Python/2.5/site-packages/django/forms/models.py" in __init__
  475.         self.queryset = queryset
File "/Library/Python/2.5/site-packages/django/forms/models.py" in _set_queryset
  483.         self.widget.choices = self.choices
File "/Users/dcramer/Development/pastethat/pastes/forms.py" in _get_choices
  41.             loop(self.queryset)
File "/Users/dcramer/Development/pastethat/pastes/forms.py" in loop
  24.                 for parent, objects in itertools.groupby(sorted(objects, key=func), key=func):
File "/Library/Python/2.5/site-packages/django/db/models/query.py" in __len__
  153.             self._result_cache.extend(list(self._iter))
File "/Library/Python/2.5/site-packages/django/db/models/query.py" in iterator
  266.         for row in self.query.results_iter():
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in results_iter
  200.         for rows in self.execute_sql(MULTI):
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in execute_sql
  1603.             sql, params = self.as_sql()
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in as_sql
  255.         ordering = self.get_ordering()
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in get_ordering
  613.                         self.model._meta, default_order=asc):
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in find_ordering_name
  666.                         order, already_seen))
File "/Library/Python/2.5/site-packages/django/db/models/sql/query.py" in find_ordering_name
  660.                 raise FieldError('Infinite loop caused by ordering.')

[Malcolm Tredinnick]

The error isn't related to data in the database. It's an error in the model definition (the ordering by parent, which uses the default model's ordering, which includes parent, etc). Replace parent with parent__id in the ordering if you want the old (somewhat incorrect) behaviour.