django.db.utils.ProgrammingError: column "manufdate" cannot be cast automatically to type date
HINT:  Specify a USING expression to perform the conversion.

class Zip(models.Model):
    category = models.ForeignKey(Category,null=True,verbose_name='Категория')
    subcategory = ChainedForeignKey(SubCategory,chained_field="category",
        chained_model_field="category",
        show_all=False,
        auto_choose=True,verbose_name='Подкатегория')
    type = models.ForeignKey(Type,verbose_name='Состояние')
    zipgroup = models.ForeignKey(ZipGroup,null=True,verbose_name='Группа запчастей')
    ziptype = models.ForeignKey(ZipType,null=True,verbose_name='Вид запчасти')
    cartype = models.ForeignKey(CarType,null=True,verbose_name='Тип авто')
    carmodel = models.ForeignKey(CarModel,null=True,verbose_name='Модель транспорта')
    carbodytype = models.ForeignKey(CarBodyType,null=True,verbose_name='Тип кузова')
    catalognumber = models.CharField(max_length=100,null=True,blank=True,verbose_name='Номер по каталогу')
    manufdate = models.CharField(max_length=4,null=True,verbose_name='Год выпуска')
    title = models.CharField(max_length=100,verbose_name='Заголовок объявления')
    description = models.TextField(null=True,verbose_name='Описание')
    price = models.IntegerField(verbose_name='Цена')
    user = models.ForeignKey(User,verbose_name='Пользователь')
    creation_date = models.DateTimeField('date published')
    is_sell = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)
    likes = models.IntegerField(default=0)