无法分配 “U'' ”： “Vote.design” 必须是一个 “设计” 实例

Question

型号：

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

观点：

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'), 

如果我尝试例如：

127 .0.0.1：8000 /票/ 1/3

我有这样的错误：

ValueError at /vote/1/3/

Cannot assign "u'1'": "Vote.design" must be a "Design" instance.

Answer 1

Vote.design必须是Design实例，而不是一个号码：

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('/') 

或者与快捷方式：

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

变化design到design_id，它会改正错误

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

Answer 3

你需要找回Design模型的一个实例，并将Vote的design属性指定为：

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('/')