I've run into an infinite loop under some circumstances with raw()
queries and overridden __init__ methods in models. Here's the
smallest test case I could come up with that exhibits the problem:
from django.db import models
class ModelWithSlug(models.Model):
slug = models.SlugField(unique = True, max_length = 100)
def __init__(self, *args, **kwargs):
super(ModelWithSlug, self).__init__(*args, **kwargs)
print getattr(self, self.slug_field) # <-----------------
def save(self, **kwargs):
self.slug = self.name
super(ModelWithSlug, self).save(**kwargs)
class Meta:
abstract = True
class Package(models.Model):
name = models.CharField(max_length = 100, null = False, blank =
False)
class Album(ModelWithSlug):
name = models.CharField(max_length = 100)
is_singles = models.BooleanField(default = False)
slug_field = "name"
package = models.ForeignKey(Package, related_name='albums')
def __init__(self, *args, **kwargs):
super(Album, self).__init__(*args, **kwargs)
print self.package # <-----------------
def test():
p, _ = Package.objects.get_or_create(name = "p")
a, _ = Album.objects.get_or_create(name = "hello", package = p)
albums = Album.objects.raw("SELECT id, name, package_id FROM
managerfail2_album")
return list(albums)[0].slug
Now, from what I understand, when the test() method is executed, the
__init__ of ModelWithSlug is called, which tries to retrieve the slug
field, which wasn't part of the raw() query, so django tries to
retrieve it. But then looking further down the stack, the "print
self.package" fails, and the whole process loops infinitely. If I
comment out *either* of the print statements, everything is happy. If
I add "slug" to the raw() query, everything is happy. Here's the
first couple of loops of the traceback:
/home/amagee/tmp/managerfail2/models.pyc in test()
36 a, _ = Album.objects.get_or_create(name = "hello", package =
p)
37
38 albums = Album.objects.raw("SELECT id, name, package_id FROM
managerfail2_album")
---> 39 return list(albums)[0].slug
40
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query_utils.pyc in __get__(self, instance, owner)
100 val = getattr(
101
cls._base_manager.filter(pk=instance.pk).only(name).using(
--> 102 instance._state.db).get(),
103 self.field_name
104 )
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in get(self, *args, **kwargs)
342 if self.query.can_filter():
343 clone = clone.order_by()
--> 344 num = len(clone)
345 if num == 1:
346 return clone._result_cache[0]
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in __len__(self)
80 self._result_cache = list(self._iter)
81 else:
---> 82 self._result_cache = list(self.iterator())
83 elif self._iter:
84 self._result_cache.extend(self._iter)
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in iterator(self)
281 row_data =
row[index_start:aggregate_start]
282 pk_val = row_data[pk_idx]
--> 283 obj = model_cls(**dict(zip(init_list,
row_data)))
284 else:
285 # Omit aggregates in object creation.
/home/amagee/tmp/managerfail2/models.pyc in __init__(self, *args,
**kwargs)
28
29 def __init__(self, *args, **kwargs):
---> 30 super(Album, self).__init__(*args, **kwargs)
31 print self.package # <-----------------
32
/home/amagee/tmp/managerfail2/models.pyc in __init__(self, *args,
**kwargs)
7 super(ModelWithSlug, self).__init__(*args, **kwargs)
8
----> 9 print getattr(self, self.slug_field) # <-----------------
10
11 def save(self, **kwargs):
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query_utils.pyc in __get__(self, instance, owner)
100 val = getattr(
101
cls._base_manager.filter(pk=instance.pk).only(name).using(
--> 102 instance._state.db).get(),
103 self.field_name
104 )
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in get(self, *args, **kwargs)
342 if self.query.can_filter():
343 clone = clone.order_by()
--> 344 num = len(clone)
345 if num == 1:
346 return clone._result_cache[0]
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in __len__(self)
80 self._result_cache = list(self._iter)
81 else:
---> 82 self._result_cache = list(self.iterator())
83 elif self._iter:
84 self._result_cache.extend(self._iter)
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in iterator(self)
281 row_data =
row[index_start:aggregate_start]
282 pk_val = row_data[pk_idx]
--> 283 obj = model_cls(**dict(zip(init_list,
row_data)))
284 else:
285 # Omit aggregates in object creation.
/home/amagee/tmp/managerfail2/models.pyc in __init__(self, *args,
**kwargs)
29 def __init__(self, *args, **kwargs):
30 super(Album, self).__init__(*args, **kwargs)
---> 31 print self.package # <-----------------
32
33
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
fields/related.pyc in __get__(self, instance, instance_type)
294 return getattr(instance, cache_name)
295 except AttributeError:
--> 296 val = getattr(instance, self.field.attname)
297 if val is None:
298 # If NULL is an allowed value, return it.
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query_utils.pyc in __get__(self, instance, owner)
100 val = getattr(
101
cls._base_manager.filter(pk=instance.pk).only(name).using(
--> 102 instance._state.db).get(),
103 self.field_name
104 )
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in get(self, *args, **kwargs)
342 if self.query.can_filter():
343 clone = clone.order_by()
--> 344 num = len(clone)
345 if num == 1:
346 return clone._result_cache[0]
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in __len__(self)
80 self._result_cache = list(self._iter)
81 else:
---> 82 self._result_cache = list(self.iterator())
83 elif self._iter:
84 self._result_cache.extend(self._iter)
/home/amagee/playfi_env/lib/python2.6/site-packages/django/db/models/
query.pyc in iterator(self)
281 row_data =
row[index_start:aggregate_start]
282 pk_val = row_data[pk_idx]
--> 283 obj = model_cls(**dict(zip(init_list,
row_data)))
284 else:
285 # Omit aggregates in object creation.
/home/amagee/tmp/managerfail2/models.pyc in __init__(self, *args,
**kwargs)
28
29 def __init__(self, *args, **kwargs):
---> 30 super(Album, self).__init__(*args, **kwargs)
31 print self.package # <-----------------
32
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