django - 无法分配“u'1'”：“Vote.design”必须是“Design”实例

Question

楷模：

class Vote(models.Model):
    user = models.ForeignKey(User)
    design = models.ForeignKey(Design)
    vote = models.DecimalField(max_digits=2,decimal_places=1, choices=RATE_CHOICES)

意见：

def add_vote(request, id, vote):
    user = request.user
    Vote.objects.create(user=user, design = id, vote = vote)
    return HttpResponseRedirect('/')

网址：

url(r'^vote/(?P<id>\d+)/(?P<vote>\d{1,5})/', 'app.views.add_vote'),

例如，如果我尝试：

127.0.0.1:8000/投票/1/3

我有这个错误：

/vote/1/3/ 处的 ValueError

无法分配“u'1'”：“Vote.design”必须是“Design”实例。

Answer 1

Vote.design必须是Design实例，而不是数字：

from django.http import Http404

def add_vote(request, id, vote):
    user = request.user
    try:
        design = Design.objects.get(pk=id)
    except Design.DoesNotExist:
        raise Http404

    Vote.objects.create(user=user, design=design, vote=vote)
    return HttpResponseRedirect('/')

或使用快捷方式：

from django.shortcuts import get_object_or_404

def add_vote(request, id, vote):
    user = request.user
    design = get_object_or_404(Design, pk=id)
    Vote.objects.create(user=user, design=design, vote=vote)
    return HttpResponseRedirect('/')

Answer 2

更改design为design_id，它将修复您的错误

def add_vote(request, id, vote):
    user = request.user
    Vote.objects.create(user=user, design_id = id, vote = vote)
    return HttpResponseRedirect('/')

Answer 3

您需要检索Design模型的实例并将其design属性分配Vote给：

def add_vote(request, id, vote):
    user = request.user
    design = Design.objects.get(id=id)
    Vote.objects.create(user=user, design=design, vote=vote)
    return HttpResponseRedirect('/')