>>> #
... from django.db import models
... from django.utils.translation import gettext_lazy as _
...
...
... class Customer(BaseModel):
...     firstname = models.CharField(verbose_name=_('First Name'), max_length=100, null=False, blank=False, default=None)
...     lastname = models.CharField(verbose_name=_('Last Name'), max_length=100, null=False, blank=False, default=None)
...     birthdate = models.DateField(verbose_name=_('Birth Date'), null=True, blank=True, default=None)
...     photo = models.ImageField(verbose_name=_('Photo'), upload_to='contact/', null=True, blank=True, default=None)
...
...     @staticmethod
...     def add(firstname, lastname, birthdate, photo):
...         customer = Customer(firstname=firstname, lastname=lastname, birthdate=birthdate, photo=photo)
...         customer.full_clean()
...         customer.save()
...         return customer
...
...     def __str__(self):
...         return f'{self.firstname} {self.lastname}'
...
...     class Meta:
...         verbose_name = _('Customer')
...         verbose_name_plural = _('Customers')