[英]Failed with the get_object_or_404 django
這是代碼:
>>> 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
self.model._meta.object_name
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
1
>>> obj.url
'http://google.com'
我現在正在練習django模型。問題是當我使用get_object_or_404試圖獲取與第二個關鍵字參數匹配的數據時,它以某種方式失敗了。當我使用get()方法時,它成功了,我認為我應該得到同樣的結果在這里。
#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)
q.save()
print(q.id)
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)
我想問題在於重寫all()
方法。 當您使用get_object_or_404()
它正在調用 _get_queryset()
函數,該函數返回manager.all()
。 但是由於覆蓋, all()
僅返回未激活的對象,並且get_object_or_404(KirrURL,shortcode='pric3e')
為空。
您的自定義管理器產生不一致的結果,因為並非總是調用.all()
。 如果希望該管理器始終過濾掉特定實例,則應重寫get_queryset()
。 確保在您的自定義管理器上方包括一個默認管理器,以便您仍然可以訪問例如admin中的所有實例。
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()
現在KurrURL.objects.all()
將返回所有實例(並且get_object_or_404(KirrURL, shortcode='pric3e')
將能夠找到您的實例),但是您可以使用KirrURL.custom.all()
訪問所有非活動實例。
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