类型 'method' 的 Django 对象没有 len()

Question

我刚刚在Django中的ListView中添加了分页，但它返回了object of type 'method' has no len()错误，尽管我正在重写get_queryset方法，并且它没有返回与queryset不同的任何内容。

导致错误的视图如下所示：

class ProductList(ListView):
paginate_by = 10
model = Product
context_object_name = 'products'
template_name = 'catalog/product/product_list.html'
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super().dispatch(*args, **kwargs)
def queryset(self):
categories = Category.objects.filter(company=self.request.user.profile.company)
return Product.objects.filter(category__in=categories)
def get_context_data(self, **kwargs):
context = super(ProductList, self).get_context_data(**kwargs)
context['customers'] = Customer.objects.filter(company=self.request.user.profile.company)
context['categories'] = Category.objects.filter(company=self.request.user.profile.company)
return context

完整的回溯：

Traceback (most recent call last):
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/handlers/exception.py", line 47, in inner
response = get_response(request)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/handlers/base.py", line 179, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/views/generic/base.py", line 70, in view
return self.dispatch(request, *args, **kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/utils/decorators.py", line 43, in _wrapper
return bound_method(*args, **kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
return view_func(request, *args, **kwargs)
File "/home/ubuntu/dawipo/catalog/views.py", line 105, in dispatch
return super().dispatch(*args, **kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/views/generic/base.py", line 98, in dispatch
return handler(request, *args, **kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/views/generic/list.py", line 157, in get
context = self.get_context_data()
File "/home/ubuntu/dawipo/catalog/views.py", line 113, in get_context_data
context = super(ProductList, self).get_context_data(**kwargs)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/views/generic/list.py", line 119, in get_context_data
paginator, page, queryset, is_paginated = self.paginate_queryset(queryset, page_size)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/views/generic/list.py", line 69, in paginate_queryset
page = paginator.page(page_number)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/paginator.py", line 73, in page
number = self.validate_number(number)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/paginator.py", line 51, in validate_number
if number > self.num_pages:
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/utils/functional.py", line 48, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/paginator.py", line 100, in num_pages
if self.count == 0 and not self.allow_empty_first_page:
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/utils/functional.py", line 48, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/home/ubuntu/dawipoenv/lib/python3.6/site-packages/django/core/paginator.py", line 95, in count
return len(self.object_list)
Exception Type: TypeError at /catalog/list/
Exception Value: object of type 'method' has no len()

在不显示此错误的情况下，如何使用覆盖查询集进行分页？

Answer 1

您覆盖的方法是get_queryset(…)[Django-doc]，而不是queryset，queryset是一个属性，您可以为此设置QuerySet对象，但不能将queryset用作方法。因此，您将其实现为：

from django.contrib.auth.mixins importLoginRequiredMixin
class ProductList(LoginRequiredMixin, ListView):
paginate_by = 10
model = Product
context_object_name = 'products'
template_name = 'catalog/product/product_list.html'

# useget_queryset, notqueryset
defget_queryset(self, *args, **kwargs):
return super().get_queryset(*args, **kwargs).filter(
category__company=self.request.user.profile.company
)
# …

---

注意：您可以使用LoginRequiredMixinmixin[Django-doc]。