class User(AbstractUser):
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = []
    username = models.CharField(max_length=100, null=True, blank=True)
    first_name = models.CharField('Имя', max_length=100)
    email = models.EmailField('Email', max_length=100, unique=True)
    language = models.ForeignKey(
        Language, models.SET_NULL, null=True)

class Car(models.Model):
    name = models.TextField('Название автомобиля', default='{"eng": "", "rus": ""}')
    year_of_issue = models.DateField('Дата выпуска')
    add_date = models.DateField('Дата добавления', auto_now_add=True)
    status = models.BooleanField('Машина занята?', default=False)
    renter = models.ForeignKey(User, models.SET_NULL, blank=True, null=True)