Question

免责声明：我是Django的新手（尝试自学），目前我正在尝试获得一个几乎没有文档https://github.com/byteweaver/django-coupons为我正在构建的应用程序工作的软件包。

我正在尝试兑换我在后端创建的优惠券，但我收到了一些非常奇怪的错误。当我提交表单时，<django.db.models.query_utils.DeferredAttribute object at 0x10e6ee898>返回到表单框中，我收到了＃34;此代码无效＆＃34;错误。对此我提供的任何帮助都会非常感激，因为我现在已经用头撞墙了几个小时。

views.py

def gift_card(request):

user = request.user

if request.user.is_authenticated:
    edit_profile = EditProfileForm(user=user)
    redeem = CouponForm()
    if request.method == 'POST':
        edit_profile = EditProfileForm(request.POST, user=user)
        redeem = CouponForm(request.POST, user=user)
        if redeem.is_valid():
            Coupon.redeem(request.POST, user=user)
        else:
            edit_profile = EditProfileForm(user=user)
        return render(request, 'main/profile.html', {'edit_profile': edit_profile, 'redeem': redeem})

    return render(request, 'main/profile.html', {'edit_profile': edit_profile, 'redeem': redeem})
else:
    return redirect('/')

forms.py

class CouponForm(forms.Form):
code = forms.CharField(required=True,
                       label=_("code"),
                       widget=forms.TextInput
                       (attrs={'placeholder':_('Code'),
                               'class': 'text-center'}))

def __init__(self, *args, **kwargs):
    self.user = None
    self.types = None
    if 'user' in kwargs:
        self.user = kwargs['user']
        del kwargs['user']
    if 'types' in kwargs:
        self.types = kwargs['types']
        del kwargs['types']
    super(CouponForm, self).__init__(*args, **kwargs)

def clean_code(self):
    code = self.cleaned_data['code']
    try:
        coupon = Coupon.objects.get(code=code)
    except Coupon.DoesNotExist:
        raise forms.ValidationError(_("This code is not valid."))
    self.coupon = coupon

    if self.user is None and coupon.user_limit is not 1:
        # coupons with can be used only once can be used without tracking the user, otherwise there is no chance
        # of excluding an unknown user from multiple usages.
        raise forms.ValidationError(_(
            "The server must provide an user to this form to allow you to use this code. Maybe you need to sign in?"
        ))

    if coupon.is_redeemed:
        raise forms.ValidationError(_("This code has already been used."))

    try:  # check if there is a user bound coupon existing
        user_coupon = coupon.users.get(user=self.user)
        if user_coupon.redeemed_at is not None:
            raise forms.ValidationError(_("This code has already been used by your account."))
    except CouponUser.DoesNotExist:
        if coupon.user_limit is not 0:  # zero means no limit of user count
            # only user bound coupons left and you don't have one
            if coupon.user_limit is coupon.users.filter(user__isnull=False).count():
                raise forms.ValidationError(_("This code is not valid for your account."))
            if coupon.user_limit is coupon.users.filter(redeemed_at__isnull=False).count():  # all coupons redeemed
                raise forms.ValidationError(_("This code has already been used."))
    if self.types is not None and coupon.type not in self.types:
        raise forms.ValidationError(_("This code is not meant to be used here."))
    if coupon.expired():
        raise forms.ValidationError(_("This code is expired."))
    return code

models.py

@python_2_unicode_compatible
class Coupon(models.Model):
    value = models.IntegerField(_("Value"), help_text=_("Arbitrary coupon value"))
    code = models.CharField(
        _("Code"), max_length=30, unique=True, blank=True,
        help_text=_("Leaving this field empty will generate a random code."))
    type = models.CharField(_("Type"), max_length=20, choices=COUPON_TYPES)
    user_limit = models.PositiveIntegerField(_("User limit"), default=1)
    created_at = models.DateTimeField(_("Created at"), auto_now_add=True)
    valid_until = models.DateTimeField(
        _("Valid until"), blank=True, null=True,
        help_text=_("Leave empty for coupons that never expire"))
    campaign = models.ForeignKey('Campaign', verbose_name=_("Campaign"), blank=True, null=True, related_name='coupons')

    objects = CouponManager()

    class Meta:
        ordering = ['created_at']
        verbose_name = _("Coupon")
        verbose_name_plural = _("Coupons")

    def __str__(self):
        return self.code

    def save(self, *args, **kwargs):
        if not self.code:
            self.code = Coupon.generate_code()
        super(Coupon, self).save(*args, **kwargs)

    def redeem(self, user=None):
        try:
            coupon_user = self.users.get(user=user)
        except CouponUser.DoesNotExist:
            try:  # silently fix unbouned or nulled coupon users
                coupon_user = self.users.get(user__isnull=True)
                coupon_user.user = user
            except CouponUser.DoesNotExist:
                coupon_user = CouponUser(coupon=self, user=user)
        coupon_user.redeemed_at = timezone.now()
        coupon_user.save()
        redeem_done.send(sender=self.__class__, coupon=self)

更新 - Coupon.redeem出错（请参阅代码视图）：

'QueryDict' object has no attribute 'users'

in models.py | coupon_user = self.users.get(user=user)

Answer 1

您创建CouponForm实例的方式无效。你在做什么

redeem = CouponForm({'code': Coupon.code}, user=user)

在此，您将code的初始数据作为Coupon.code传递，这是不正确的。您应该传递code的有效值ie。一些文字。但是，您在Coupon.code传递Coupon模型的属性，而非预期值。

由于您的表单包含code字段，您可以传递request.POST以使用提交的值来实例化表单。

redeem = CouponForm(request.POST, user=user)

此外，您要多次实例化表单（例如if和else的{{1}}部分），不要认为您需要这个。

Answer 2

在将Form或ModelForm用作中间步骤时，您不应定义其字段，而应仅使用Class Meta及其fields=选项进行选择要显示的字段。

表单返回<django.db.models.query_utils.deferredattribute object =“”at =“”0x10e6ee898 =“”>

2 个答案: