python-为什么Django给我这个“违反非空约束”错误？

错误：

null value in column “postal_code_id” violates not-null constraint

表格：

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())

显然,表单确实具有有效的PostalCode对象,因此我不确定为什么要说它违反了非null约束.当然,我对表单做了一些有趣的事情：

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,我将用文本字段替换postal_code字段,然后在“ clean”方法中查找/创建对象.为什么这会混淆Django？它最终获得了所需的对象,不是吗？

解决方法:

您将排除postal_code,这将导致模型表单稍后在尝试保存期间跳过字段.我遇到了类似的问题,不得不跟踪django代码以找出行为.值得一提.

您要做的是设置用于postal_code字段的小部件,而不是排除然后包括.

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

那应该允许模型表单正确验证字段并保存它.为了简洁起见,我将其余表格排除在外.

编辑：

试图将CharField用作ForeignKey在ModelForm中充满了恐惧.而是将其转换为常规形式.无论如何,您似乎已经在定义大多数字段.然后依靠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 save方法的保存方法,然后就可以使用.

标签：django-forms,python,django,django-models
来源： https://codeday.me/bug/20191102/1992127.html