Question

我在构建自定义表单（仅默认模型表单）方面没有太多经验，我在这里寻求帮助。我正在尝试构建一个将从用户获取“feed_url”的表单，如果它已经存在，只需将引用添加到UserFeed模型中。如果它不存在，它应该将它添加到Feed模型，并在UserFeed模型中也引用它。

模型

class Category(models.Model):
    name = models.CharField(unique=False, max_length=64)
    user = models.ForeignKey(User)
    slug = AutoSlugField(populate_from='name', always_update='True', unique_with='user')


    def __unicode__(self):
        return self.name

    class Meta:
        ordering = ('name',)


class Feed(models.Model):
    feed_url = models.URLField(unique=True)

    def __unicode__(self):
        return self.feed_url


class UserFeed(models.Model):
    feed = models.ForeignKey(Feed)
    title = models.CharField(max_length=64)
    category = models.ForeignKey(Category)
    user = models.ForeignKey(User)
    slug = AutoSlugField(populate_from='title', always_update='True', unique_with='user')

    def __unicode__(self):
        return self.title

    class Meta:
        ordering = ('title',)

形式

class UserFeedForm(forms.Form):
    feed_url = forms.URLField()
    title = forms.CharField(max_length=64)
    category = forms.ModelChoiceField(Category)
    user = forms.HiddenInput()

视图

def addfeed(request):
    categories = Category.objects.filter(user=request.user)
    feeds = Feed.objects.all()
    if request.method == 'POST':
        form = UserFeedForm(request.POST)
        form.fields['category'].queryset = categories
        if form.is_valid():
            feed = form.save(commit=False)
            if form.fields['feed_url'] in feeds:
                ##### add to Feed object and add reference to UserFeed object
                feed.user = request.user
                feed.save()
            else:
                ##### get id from Feed object and add reference to UserFeed object
                feed.user = request.user
                feed.save()
            return HttpResponseRedirect("/reader/manage")
    else:
        form = UserFeedForm()
        form.fields['category'].queryset = categories
    context = {'form': form,}
    return expand_context_and_render(request, context, 'reader/form.html')

有人可以指出我正确的方向吗？感谢

更新现在我更新了我的观点和表格如下：

形式

class UserFeedForm(forms.ModelForm):
    feed = forms.URLField()
    title = forms.CharField(max_length=64)
    category = forms.ModelChoiceField(Category)
    user = forms.HiddenInput()

    class Meta:
        model = UserFeed
        fields = ['feed', 'title', 'category']

视图

def addfeed(request):
    categories = Category.objects.filter(user=request.user)
    feeds = Feed.objects.all()
    if request.method == 'POST':
        form = UserFeedForm(request.POST)
        form.fields['category'].queryset = categories
        if form.is_valid():
            feed = form.cleaned_data.get('feed')
            if feed in feeds:
                ##### get id from Feed and add reference to UserFeed
                existing_feed = Feed.objects.get(feed_url=feed)
                form.feed = existing_feed.id
                form.user = request.user
                form.save(commit=True)
            else:
                ##### add to Feed object and then add reference to UserFeed object
                Feed.object.create(feed_url=feed)
                existing_feed = Feed.objects.get(feed_url=feed)
                form.feed = existing_feed.id
                form.user = request.user
                form.save(commit=True)
            return HttpResponseRedirect("/reader/manage")
    else:
        form = UserFeedForm()
        form.fields['category'].queryset = categories
    context = {'page_title': page_title,
               'form': form,
               }
    return expand_context_and_render(request, context, 'reader/form.html')

我想我越来越近但它仍然无效，给我这个错误： “无法指定”u'http://feeds.bbci.co.uk/news/rss.xml'“：”UserFeed.feed“必须是”Feed“实例。”

任何想法我该如何解决这个问题？感谢

Answer 1

尝试在文档中查看此question和inline formsets。

此外，在您的UserFieldForm中，feed被定义为URLField。所以在你看来，在这一行：

feed = form.get_cleaned_data.get('feed')

您的Feed变量只是一个字符串，而不是Feed对象。这可能是您的错误发生的地方？那是inline formsets可以帮助你的地方。此外，此行还会使您的if feed in feeds:语句失败，因为feed只是一个字符串，而feeds是所有Feed实例的Queryset。我认为这会导致您的观点始终以else块结束？

我自己是Django的新手，但我希望这可以帮助你。

Answer 2

您正在寻找的逻辑是：

检查Feed是否存在。
如果存在，请抓取它。
如果它没有创建新的Feed。
将Feed与UserFeed对象相关联。

get_or_create方法执行第1-3部分，因此您需要以下内容：

if form.is_valid():
    obj = form.save(commit=False)
    feed = form.cleaned_data.get('feed')
    feed_obj, created = Feed.objects.get_or_create(feed_url=feed)
    obj.feed = feed_obj
    obj.save()
    return HttpResponseRedirect("/reader/manage")

Answer 3

我终于得到了这样的工作：

形式

class UserFeedForm(forms.Form):
    feed = forms.URLField()
    title = forms.CharField(max_length=64)
    category = forms.ModelChoiceField(Category)
    user = forms.HiddenInput()

    class Meta:
        model = UserFeed
        fields = ['feed', 'title', 'category']

视图

def addfeed(request):
    user = request.user
    categories = Category.objects.filter(user=request.user)
    if request.method == 'POST':
        form = UserFeedForm(request.POST)
        form.fields['category'].queryset = categories
        if form.is_valid():
            feed = form.cleaned_data['feed']
            category = form.cleaned_data['category']
            title = form.cleaned_data['title']
            feed_obj, created = Feed.objects.get_or_create(feed_url=feed)
            obj = UserFeed(feed=feed_obj, title=title, category=category, user=user)
            obj.save()
        return HttpResponseRedirect("/reader/manage")
    else:
        form = UserFeedForm()
        form.fields['category'].queryset = categories
    context = {'page_title': page_title,
               'form': form,
               }
    return expand_context_and_render(request, context, 'reader/form.html')

以下答案中的两个提示都指向了正确的方向。谢谢！

Django在两个模型上形成验证和操作

3 个答案: