Django ModelForm-以有效形式访问自定义字段

我已经按照下面的说明向ModelForm添加了一个自定义字段，但是我无法在UpdateView中访问该字段。我已尝试打印该对象，但现场设备\u circuit\u子网不在其中，同时在对象外部引用它会引发错误

是否可以获取模型表单中自定义字段的值，以便在保存对象之前使用它

谢谢

forms.py

class SiteServiceForm(forms.ModelForm):
    class Meta:
        model = DeviceCircuitSubnets
        fields = ['device','circuit','subnet','monitored','interface_name','get_bgp','wb_bgp','db_bgp','get_interface','wb_interface','db_interface','get_aws','wb_aws','db_aws']

        def __init__(self, *args, **kwargs):
            self.is_add = kwargs.pop("is_add", False)
            site_id = kwargs.pop("site_id")
            super(SiteServiceForm, self).__init__(*args, **kwargs)
            self.fields['device'].required = False
            self.fields['circuit'].required = False
            self.fields['subnet'].required = False
            self.fields['device_circuit_subnet'] = DeviceCircuitSubnetField(
                    queryset=DeviceCircuitSubnets.objects.filter(device__site_id=site_id).select_related(
                        'device', 'circuit', 'subnet'
                    ),
                    label='Device / Circuit / Subnet'
            )
            self.helper = FormHelper(self)
            self.helper.form_id = 'site_service_form'
            self.helper.form_method = 'POST'
            self.helper.layout = Layout(
                Div(
                    Div(
                        Div(HTML('<i class="fa fa-bolt fa-fw"></i> Service'), css_class='card-header'),
                        Div(
                            Div(    
                                Div(
                                    Field('device_circuit_subnet', css_class='chosen'),

                                css_class='col-lg-6'
                                ),     
                                Div(
    ...

控制台输出表单打印对象

{'_state': <django.db.models.base.ModelState object at 0x7f31fedefcf8>, 'id': None, 'device_id': None, 'circuit_id': None, 'subnet_id': None, 'active_link': False, 'active_link_timestamp': None, 'monitored': False, 'interface_name': 'll', 'get_bgp': False, 'wb_bgp': False, 'db_bgp': False, 'get_interface': False, 'wb_interface': False, 'db_interface': False, 'get_aws': False, 'wb_aws': False, 'db_aws': False}

{u state'：，'id'：None，'device'id'：None，'circuit'u id'：None，'subnet'id'：None，'active'u link'：False，'active'u timestamp'：None，'monitored'：False，'wb'bgp'：False，'db'u interface'：False，'wb'u interface'：False，'db'u interface'：False，'get'aws'：False，'wb'aws'：Falselse}

该字段的格式为已清除的\u数据

dcs = form.cleaned_data['device_circuit_subnet']

---

该字段的格式为U数据

dcs = form.cleaned_data['device_circuit_subnet']

---

谢谢你的帮助谢谢你的帮助