python - 为什么 Django 给我这个 "violates not-null constraint"错误？

Question

错误:

null value in column "postal_code_id" violates not-null constraint

形式:

def add(request):
    if request.method == 'POST':
        address_form = AddressForm(request.POST)
        company_form = CompanyForm(request.POST)
        if address_form.is_valid() and company_form.is_valid():
            print address_form.cleaned_data['postal_code'] # <-- prints (<PostalCode: V4N 1K6>, False)
            address_form.save() # <------------------------------- occurs here
        else:
            print 'Address errors',address_form.errors
            print 'Company errors', company_form.errors
    else:
        address_form = AddressForm()
        company_form = CompanyForm()
    return render(request, 'company/add.html', locals())

很明显，表单确实有一个有效的 PostalCode 对象，所以我不确定为什么它说它违反了非空约束。当然，我正在对表单做一些有趣的事情:

class AddressForm(ModelForm):
    postal_code = CharField(max_length=10, validators=[validate_postal_code])
    city = CharField(max_length=50, validators=[validate_non_whitespace])
    province = CharField(max_length=50, validators=[validate_non_whitespace])
    country = CharField(max_length=50, initial='Canada', validators=[validate_non_whitespace])

    def clean_postal_code(self):
        code = self.cleaned_data['postal_code']
        code = code.upper()
        code = re.sub('[^A-Z0-9]', '', code)
        code = code[:3] + ' ' + code[-3:]
        return code

    def clean_country(self):
        country = self.cleaned_data['country']

        try:
            country = Country.objects.get(name__iexact=country)
        except Country.DoesNotExist:
            raise ValidationError('Country does not exist')

        return country

    def clean_province(self):
        province = self.cleaned_data['province']

        if not Province.objects.filter(name__iexact=province).exists():
            raise ValidationError('Province does not exist')

        return province

    def clean(self):
        data = self.cleaned_data

        if 'country' in data and 'province' in data:
            try:
                data['province'] = Province.objects.get(country=data['country'], name__iexact=data['province'])
                if 'city' in data:
                    data['city'] = City.objects.get_or_create(name__iexact=data['city'], province=data['province'], defaults={'name':data['city']})[0]
                    if 'postal_code' in data:
                        data['postal_code'] = PostalCode.objects.get_or_create(code=data['postal_code'], city=data['city'])
            except Province.DoesNotExist:
                self._errors['province'] = self.error_class(['Province does not exist in that Country'])
                del data['province']

        return data

    class Meta:
        exclude = ['postal_code']
        model = Address

具体来说，我将 postal_code 字段替换为文本字段，然后在“clean”方法中查找/创建对象。为什么这会让 Django 感到困惑？它最终获得了它需要的对象，不是吗？

Answer 1

您正在排除 postal_code，这将导致模型表单稍后在尝试保存期间跳过该字段。我遇到了类似的问题，不得不通过 django 代码进行跟踪以找出行为。顺便说一句，这是值得的。

您要做的是设置用于 postal_code 字段的小部件，而不是先排除再包含。

class AddressForm(ModelForm):
    class Meta:
        model = Address
        widgets = {
            'postal_code': CharField(max_length=10),
        }

这应该允许模型正确验证字段并保存它。为简洁起见，我排除了您表格的其余部分。

编辑:

尝试将 CharField 用于 ForeignKey 在 ModelForm 中充满了恐怖。相反，将其转换为常规形式。无论如何，您似乎已经定义了大部分领域。然后依赖于您来验证字段是否有效，并且已经是数据库的成员。创建一个行为类似于 ModelForm 保存方法的保存方法，然后就可以了。