名称错误名称"F"未定义

Question

当我尝试用这段代码在用户填写一份调查问卷后给他加10分时，显示了这个错误

然而，我遇到了一个问题。我得到错误:

models.py", line 22, in give_coins
user.coins = F('coins') + count
NameError: name 'F' is not defined

models.py

class User(AbstractUser):
user_pic = models.ImageField(upload_to='img/',default="",null=True, blank=True)
coins = models.IntegerField(default=10)
def get_image(self):
if self.user_pic and hasattr(self.user_pic, 'url'):
return self.user_pic.url
else:
return '/path/to/default/image'
def give_coins(user, count):
user.coins = F('coins') + count
user.save(update_fields=('coins',))
user.refresh_from_db(fields=('coins',))

views.py:

@require_http_methods(["POST"])
def submit_survey(request):
request.user.give_coins(count=10)
form_data = request.POST.copy()
form_items = list(form_data.items())
print("form_items", form_items)
form_items.pop(0)  # the first element is the csrf token. Therefore omit it.
survey = None
for item in form_items:
# Here in 'choice/3', '3' is '<choice_id>'.
choice_str, choice_id = item
choice_id = int(choice_id.split('/')[1])
choice = Choice.objects.get(id=choice_id)
if survey is None:
survey = choice.question.survey
choice.votes = choice.votes + 1
choice.save()
if survey is not None:
participant = Participant(survey=survey, participation_datetime=timezone.now())
participant.save()
return redirect('/submit_success/')

. .这里的错误在哪里

Answer 1

进口"F"在"models.py">如下所示:

from django.db.models import F