Null value in column "user_id" violates not-null constraint save()

import openpyxl
from django.core.management import BaseCommand
from modules.channel.models import  Card
 
 
class Command(BaseCommand):
    def handle(self, *args, **options):
        path = "/home/roma/workspase/channels/modules/channel/static/channel/Excel/1.xlsx"  # имя файла
        wb = openpyxl.load_workbook(path)
        ws1=wb["НОВОЕ"]
        m_row = ws1.max_row
        for i in range(2, m_row + 1):
            id_card = ws1.cell(row=i, column=1).value# В column= подставляем номер нужной колонки
            card = ws1.cell(row=i, column=4).value
            cam_module = ws1.cell(row=i, column=6).value
            city = ws1.cell(row=i, column=8).value
            encoding = ws1.cell(row=i, column=9).value
            location = ws1.cell(row=i, column=10).value
            comment = ws1.cell(row=i, column=13).value
            price_and_conditions = ws1.cell(row=i, column=16).value
            id_card = int(id_card)
            card_update = Card.objects.get(id=id_card)
            card_update.card = card
            card_update.cam_module = cam_module
            card_update.city_id = city
            card_update.encoding_id = encoding
            card_update.location = location
            card_update.comment = comment
            card_update.price_and_conditions = price_and_conditions
            card_update.save()
            print(card_update.id, card_update.card,)

@attach_main_log
class Card(LogModelNameMixin, models.Model):
    """
    Карты
    """
    source = models.ManyToManyField('channel.Source', verbose_name='Источники', related_name='card',
                                    blank=True, limit_choices_to={'type': Source.SOURCE_TYPE_SPUTNIK})
    city = models.ForeignKey('core.City', verbose_name='Город', related_name='card',
                             limit_choices_to={'is_active': True, 'sputnik': True})
    number = models.CharField('Номер', max_length=45,)
    encoding = models.ForeignKey('channel.CardEncoding', verbose_name='Кодировка', related_name='card',
                                 limit_choices_to={'in_use': True})
    status = models.ForeignKey('channel.CardStatus', verbose_name='Статус', related_name='card',
                               limit_choices_to={'in_use': True})
    cam_module = models.TextField('CAM Модуль', blank=True, null=True)
    comment = models.TextField('Назначение', blank=True, null=True)
    in_use = models.BooleanField('В работе', default=True, db_index=True)
    card_return = models.BooleanField('Возврат карты', default=True, db_index=True)
    module_return = models.BooleanField('Возврат модуля', default=True, db_index=True)
    location = models.TextField('Местоположение', default='', blank=True)
    price_and_conditions = models.TextField('Стоимость и условия', default='', blank=True)
    activation = models.BooleanField('Активация', default=True, db_index=True)
    activation_date = models.DateField('Дата активации',auto_now_add=True, null=True)
    date_of_receipt = models.DateField('Дата получения', auto_now_add=True, null=True)
    broadcaster = models.CharField('Вещатель', max_length=30, default='', blank=True)
 
    history = GenericRelation(History)
 
    objects = models.Manager.from_queryset(CardQuerySet)()
 
    class Meta:
        verbose_name = 'Карта'
        verbose_name_plural = 'Карты'
        permissions = (
            ('p_card_view', 'Просмотр карт доступа'),
            ('p_card_add', 'Добавлять карту доступа'),
            ('p_card_edit', 'Редактировать карту доступа')
        )
 
    def __str__(self):
        return self.number

~/workspase/channels$ ./manage.py export_from_excel
851 31026500020781
Traceback (most recent call last):
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
psycopg2.IntegrityError: null value in column "user_id" violates not-null constraint
DETAIL:  Failing row contains (1011, 2019-10-25 10:09:22.909467+00, 1, 807, {"city": "Город", "in_use": false, "number": "25026500020631", ..., 41, null).
 
 
The above exception was the direct cause of the following exception:
 
Traceback (most recent call last):
  File "./manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/home/roma/workspase/channels/modules/channel/management/commands/export_from_excel.py", line 31, in handle
    card_update.save()
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 808, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 833, in save_base
    update_fields=update_fields,
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 193, in send
    for receiver in self._live_receivers(sender)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 193, in <listcomp>
    for receiver in self._live_receivers(sender)
  File "/home/roma/workspase/channels/modules/channel/signal_receivers.py", line 72, in card_history_update
    history.save()
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 808, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 838, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 924, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/base.py", line 963, in _do_insert
    using=using, raw=raw)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/query.py", line 1076, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1112, in execute_sql
    cursor.execute(sql, params)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/raven/contrib/django/client.py", line 127, in execute
    return real_execute(self, sql, params)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/cacheops/transaction.py", line 99, in execute
    result = self._no_monkey.execute(self, sql, params)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/home/roma/workspase/venvs/channels/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: null value in column "user_id" violates not-null constraint
DETAIL:  Failing row contains (1011, 2019-10-25 10:09:22.909467+00, 1, 807, {"city": "Город", "in_use": false, "number": "25026500020631", ..., 41, null).

@receiver(pre_save, sender=Card)
def card_history_update(sender, instance, **kwargs):
    """
    Логирование изменений по картам доступа
    """
    if instance.id is not None:
        data = {
            'city': instance.city.name,
            'number': instance.number,
            'encoding': instance.encoding.title,
            'status': instance.status.title,
            'cam_module': instance.cam_module,
            'comment': instance.comment,
            'in_use': instance.in_use
        }
        history_prev = instance.history.all().order_by('-date').first()
        if history_prev is None or data != history_prev.data:
            history = History(content_object=instance, user=CuserMiddleware.get_user(), action=History.ACTION_UPDATE)
            history.data = data
            history.save()

from django.db.models.signals import pre_save
from modules.channel.models import  Card
from modules.channel.signal_receivers import card_history_update

class Command(BaseCommand):
    def handle(self, *args, **options):
        pre_save.disconnect(card_history_update, sender=Card)