CODEWITHSUNDEEP
pythondjangodjango-queryset
Saqib Ali
Saqib Ali

Reputation: 12575

Why does this very basic query on this Django model fail?

I have the following Django class:

from caching.base import CachingManager, CachingMixin
from mptt.models import MPTTModel

def make_id():
    '''
    inspired by http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram
    '''
    START_TIME = 1876545318034
    return (int(time.time()*1000) - START_TIME << 23 ) | random.SystemRandom().getrandbits(23)

class My_Class(CachingMixin, MPTTModel):
    id = models.BigIntegerField(default=make_id, primary_key=True)
    # Other Attributes Snipped here for brevity

But look what happens when I try to query this class:

>>> My_Class.objects.get(pk=5000)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "my_virtual_env/lib/python2.7/site-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "my_virtual_env/lib/python2.7/site-packages/django/db/models/query.py", line 334, in get
    self.model._meta.object_name
DoesNotExist: My_Class matching query does not exist.

Why does it fail?? How can I fix this?

Upvotes: 0

Views: 415

Answers (1)

sr3z
sr3z

Reputation: 410

It could be you have no My_Class with id = 5000

try:
    mc = My_Class.objects.get(pk=id)
except My_Class.DoesNotExist:
    mc = None

Upvotes: 2

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