I am new to Django and I am trying to learn by practicing with some project but I am stuck with this problem,
NOT NULL constraint failed: shop_product.user_id
models.py
from django.db import models
from django.conf import settings
from django.core.urlresolvers import reverse
class Category(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             related_name='category_created')
    name = models.CharField(max_length=200, db_index=True)
    slug = models.SlugField(max_length=200, db_index=True, unique=True)
    class Meta:
        ordering = ('name',)
        verbose_name = 'category'
        verbose_name_plural = 'categories'
    def __str__(self):
        return self.name
class Product(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             related_name='product_created')
    category = models.ForeignKey(Category, related_name='products')
    name = models.CharField(max_length=200, db_index=True)
    slug = models.SlugField(max_length=200, db_index=True)
    image = models.ImageField(upload_to='products/%Y/%m/%d', blank=True)
    description = models.TextField(blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    stock = models.PositiveIntegerField()
    available = models.BooleanField(default=True)
    negiotiable = models.BooleanField(default=True)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    users_like = models.ManyToManyField(settings.AUTH_USER_MODEL,
                                        related_name='product_liked',
                                        blank=True)
    class Meta:
        ordering = ('name',)
        index_together = (('id', 'slug'),)
    def __str__(self):
        return self.name
    def get_absolute_url(self):
        return reverse('products_detail',
                       args=[self.slug])
Here is my views.py but am not sure if there is problem with my views and I think the problem will have to be with my models....
views.py
from django.views.generic import *
from django.core.urlresolvers import reverse_lazy
from .models import Category, Product
class CategoryList(ListView):
    model = Category
class CategoryDetail(DetailView):
    model = Category
class ProductList(ListView):
    model = Product
class ProductDetail(DetailView):
    model = Product
class ProductCreate(CreateView):
    model = Product
    fields = ("category", 'name', 'image', 'description', 'price', 'stock','available', 'negiotiable')
class ProductUpdate(UpdateView):
    model = Product
    fields = ('name', 'image', 'description', 'price', 'stock','available', 'negiotiable')
class ProductDelete(DeleteView):
    model = Product
    success_url = reverse_lazy('product_list')
Please let me know what could be done.
 
     
     
    