無法分配 「U'' 」： 「Vote.design」 必須是一個 「設計」 實例

Question

型號：

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

觀點：

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

網址：

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

如果我嘗試例如：

127 .0.0.1：8000 /票/ 1/3

我有這樣的錯誤：

ValueError at /vote/1/3/

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

Answer 1

Vote.design必須是Design實例，而不是一個號碼：

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('/') 

或者與快捷方式：

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

變化design到design_id，它會改正錯誤

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模型的一個實例，並將Vote的design屬性指定爲：

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('/')