#############

IntegrityError at /admin/shop/product/add/
shop_product.department_id may not be NULL

############

from django.db import models

# Create your models here.

class Shop(models.Model):
	name = models.CharField(maxlength=200)

        def __str__(self):
                return self.name

        class Admin:
                pass
    
class Department(models.Model):
	shop = models.ForeignKey(Shop)
	name = models.CharField(maxlength=200)

        def __str__(self):
                return self.name

        class Admin:
                pass

class Product(models.Model):
        department = models.ManyToManyField(Department, blank=True)
        name = models.CharField(maxlength=200)
        shop = models.ForeignKey(Shop)

        def __str__(self):
                return self.name

        class Admin:
                pass