Django如何上传图像以形成

Question

这是我与表单关联的代码：

# models

class Date(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
    place = models.ForeignKey('Place', on_delete=models.CASCADE, null=True)
    title = models.CharField(max_length=64, null=True)


class Photo(models.Model):
    date = models.ForeignKey('Date', on_delete=models.CASCADE)
    image = models.ImageField(verbose_name='Photos', upload_to='media/date/photos/')

# form

class DateForm(forms.ModelForm):
    image = forms.ImageField()
    class Meta:
        model = Date
        exclude = ('user',)

# view

class CreateDateView(LoginRequiredMixin, CreateView):
    template_name = 'app/date/form.html'
    form_class = DateForm

    def form_valid(self, form):
        form.instance.user = self.request.user
        form.save() # by the way why do I save this form? Is it okay to save it in form_valid method?
        photos = self.request.FILES.getlist('image')
        for photo in photos:
            Photo.objects.create(image=photo)
        return super().form_valid(form)

问题是，如果照片对象需要Date模型id，则如何保存它。它会引发 NULL约束failed: app_photo.date_id，据我所知，我必须编写如下内容：

Photo.objects.create(date=date_from_the_form, image=photo)

但是如何从日期模型中得到pk呢？希望你能理解我的问题，如果有任何问题可以毫不犹豫地写在下面的评论部分。提前感谢！

错误

Answer 1

您需要先创建date对象。另外，每一次约会都是独一无二的吗？如果是这样的话，您需要更改模型元声明以包含unique_together。

在创建每个对象时，还需要避免for循环。它非常昂贵，因为它将对每个调用的save()进行往返访问。这就是bulk_create的作用所在，它将数据库的触点限制为一个命令来创建多个对象。

这是伪码让你去：

if len(photos) > 0:  # don't create a date if there aren't photos
  date = Date() # add your arguments

  filtered = Date.objects.filter(date=date)

  date = date.create() if not filtered.exists() else date = filtered[0]  # but this is potentially dangerous if you risk duplicate dates. Only use this if you know it's the correct date
  photos = [Photo(date=date,image=p) for p in photos]
  Photo.objects.bulk_create(photos)

祝好运!

Answer 2

您需要保存照片对象：

def form_valid(self, form):
    form.instance.user = self.request.user
    form.save() # by the way why do I save this form? Is it okay to save it in form_valid method?
    photos = self.request.FILES.getlist('image')
    for photo in photos:
        temp = Photo.objects.create(image=photo)
        temp.save()
    return super().form_valid(form)