honesty1997 honesty1997 - 11 days ago 6
Python Question

Failed with the get_object_or_404 django

This is the code:

>>> from shortener.models import KirrURL
>>> from django.shortcuts import get_object_or_404
>>> obj = get_object_or_404(KirrURL,shortcode='pric3e')

Traceback (most recent call last):File"/Users/phil/Desktop/django110/lib/python3.5/site
packages/django/shortcuts.py", line 85, in get_object_or_404
return queryset.get(*args, **kwargs)
File "/Users/phil/Desktop/django110/lib/python3.5/site-packages/django/db/models/query.py", line 385, in get
shortener.models.DoesNotExist: KirrURL matching query does not exist.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/phil/Desktop/django110/lib/python3.5/site-packages/django/shortcuts.py", line 93, in get_object_or_404
raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
django.http.response.Http404: No KirrURL matches the given query.

>>> obj = KirrURL.objects.get(shortcode='pric3e')
>>> obj
<KirrURL: http://google.com>
>>> obj.id
>>> obj.url

I am practicing django model right now.The problem is when I used the get_object_or_404 trying to get the data which match the second key word argument it somehow failed.When I used get() method.It successes.I think I think I should get the same result here.

#Model Class
class KirrURLManager(models.Manager):
def all(self,*args,**kwargs):
qs = super(KirrURLManager,self).all(*args,**kwargs)
qs_main = qs.filter(active=False)
return qs_main

def refresh_shortcodes(self,items=None):
qs = KirrURL.objects.filter(id__gte=1)
if items is not None and isinstance(items,int):
qs = qs.order_by('-id')[:items]
for q in qs:
q.shortcode = create_shortcode(q)
class KirrURL(models.Model):
url = models.CharField(max_length=220,)
shortcode = models.CharField(max_length=SHORTCODE_MAX,unique=True,blank=True)
updated = models.DateTimeField(auto_now=True)
timestamp = models.DateTimeField(auto_now_add=True)
active = models.BooleanField(default=True)
objects = KirrURLManager()
some_random = KirrURLManager()
def save(self, *args, **kwargs):
if self.shortcode is None or self.shortcode == "":
self.shortcode = create_shortcode(self)
super(KirrURL, self).save(*args, **kwargs)
def __str__(self):
return str(self.url)
def __unicode__(self):
return str(self.url)


Your custom manager is producing inconsistent results because .all() is not always called. If you want this manager to always filter out specific instances, you should override get_queryset(). Be sure to include a default manager above your custom manager so you still have a way to access all instances in e.g. the admin.

class KirrURLManager(models.Manager):
    def get_queryset(self):
        return super().get_queryset().filter(active=False)

class KirrURL(models.Model):
    objects = models.Manager() # default manager, put this one first
    custom = KirrURLManager()

Now KurrURL.objects.all() will return all instances (and get_object_or_404(KirrURL, shortcode='pric3e') will be able to find your instance), but you can access all inactive instances using KirrURL.custom.all().