How to solve UndefinedColumn error in Django

Question

I am new to Django and trying to set up a couple of models, but have run into an error I can't seem to find a fix for.

This is the error that I am getting: psycopg2.errors.UndefinedColumn: column carts_cartitem.cart_id does not exist LINE 1: SELECT "carts_cartitem"."id", "carts_cartitem"."cart_id", "c...

This is my views file:

from django.shortcuts import render, HttpResponseRedirect
from django.urls import reverse

from products.models import Product

from .models import Cart, CartItem 

def view(request):
    try:
        the_id = request.session['cart_id']
    except:
        the_id = None
    if the_id:
        cart = Cart.objects.get(id=the_id)
        context = {'cart': cart}
    else:
        empty_message = 'Your cart is empty!'
        context = {'empty': True, 'empty_message': empty_message}

    template = 'cart/view.html'
    return render(request, template, context)

def update_cart(request, slug):
    try:
        the_id = request.session['cart_id']
    except:
        #create a cart 
        new_cart = Cart()
        new_cart.save()
        request.session['cart_id'] = new_cart.id
        the_id = new_cart.id 

    cart = Cart.objects.get(id=the_id)

    try:
        product = Product.objects.get(slug=slug)
    except Product.DoesNotExist:
        pass
    except:
        pass
    cart_item, created = CartItem.objects.get_or_create(cart=cart, product=product)
    if created:
        print('created')
    new_total = 0.00
    for item in cart.cartitem_set.all():
        line_total = float(item.product.price) * item.quantity
        new_total += line_total
    request.session['items_total'] = cart.cartitem_set.count() #count products
    cart.total = new_total
    cart.save()

    return HttpResponseRedirect(reverse('cart'))

These are my models:

from django.db import models

class Product(models.Model):
    title = models.CharField(max_length=120)
    description = models.TextField(null=True, blank=True)
    price = models.DecimalField(decimal_places=2, max_digits=100, default=29.99)
    sale_price = models.DecimalField(decimal_places=2, max_digits=100, null=True, blank=True)
    slug = models.SlugField(unique=True)
    timestamp = models.DateTimeField(auto_now_add= True, auto_now=False)
    updated = models.DateTimeField(auto_now_add= False, auto_now=True)
    active = models.BooleanField(default=True)

    def __str__(self):
        return self.title

    class Meta:
        unique_together = ('title', 'slug')

    def get_absolute_url(self):
        return reverse('single_product', kwargs={'slug': self.slug})

class Cart(models.Model):
    total = models.DecimalField(max_digits=100, decimal_places=2, default=0.00)
    timestamp = models.DateTimeField(auto_now_add= True, auto_now=False)
    updated = models.DateTimeField(auto_now_add= False, auto_now=True)
    active = models.BooleanField(default=True)

    def __str__(self):
        return "Cart id: %s" %(self.id)

class CartItem(models.Model):
    cart = models.ForeignKey(Cart, on_delete = models.CASCADE, blank=True, null=True)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    quantity = models.IntegerField(default=1)
    line_total = models.DecimalField(default=10.99, max_digits=1000, decimal_places=2)
    timestamp = models.DateTimeField(auto_now_add= True, auto_now=False)
    updated = models.DateTimeField(auto_now_add= False, auto_now=True)

    def __str__(self):
        return self.product.title

Traceback:

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/cart/slug_one/

Django Version: 2.2.1
Python Version: 3.6.1
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'products',
 'carts']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

The above exception (column carts_cartitem.cart_id does not exist
LINE 1: SELECT "carts_cartitem"."id", "carts_cartitem"."cart_id", "c...
                                      ^
) was the direct cause of the following exception:

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/Users/me/Desktop/farmacia.testing/carts/views.py" in update_cart
  44.     cart_item, created = CartItem.objects.get_or_create(cart=cart, product=product)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/manager.py" in manager_method
  82.                 return getattr(self.get_queryset(), name)(*args, **kwargs)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/query.py" in get_or_create
  538.             return self.get(**kwargs), False

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/query.py" in get
  402.         num = len(clone)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/query.py" in __len__
  256.         self._fetch_all()

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/query.py" in _fetch_all
  1242.             self._result_cache = list(self._iterable_class(self))

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/query.py" in __iter__
  55.         results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in execute_sql
  1100.             cursor.execute(sql, params)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in execute
  99.             return super().execute(sql, params)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in execute
  67.         return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute_with_wrappers
  76.         return executor(sql, params, many, context)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/utils.py" in __exit__
  89.                 raise dj_exc_value.with_traceback(traceback) from exc_value

File "/Users/me/.local/share/virtualenvs/farmacia.testing-0E8ur1aw/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

Exception Type: ProgrammingError at /cart/slug_one/
Exception Value: column carts_cartitem.cart_id does not exist
LINE 1: SELECT "carts_cartitem"."id", "carts_cartitem"."cart_id", "c...

First guess: You changed your models and did not run [migrations](https://docs.djangoproject.com/en/2.2/topics/migrations/)? — dhke, May 04 '19 at 06:06
`CartItem` model has no field called `cart_id`. Please show the traceback so we can see cause of error — HenryM, May 04 '19 at 07:09
`CartItem` should have a column `cart_id` generated for the foreign key to `cart` (see https://docs.djangoproject.com/en/2.2/ref/models/fields/#database-representation). `makemigrations` does not report anything? — dhke, May 04 '19 at 08:21
Even when I make changes for some reason if I run python manage.py makemigrations, I get the output 'No changes detected'. I have to run python manage.py app_name to get the migrations to appear any reason for this? As I used to be able to run without app_name and it would show the migrations. — cisco, May 04 '19 at 22:41

score 0 · Answer 1 · answered May 04 '19 at 23:06

0

Looks like the carts_cartitem table was corrupt. As a few were pointing out that cart_id was not present when I took a look at the table. For some reason I could not get the migrations to update. The fix was to delete the database and run the migrations newly and is now working as intended.

answered May 04 '19 at 23:06

cisco

101
2
13

6

but what if you are in production stage, then would you prefer to delete your database? I am getting the same error, but there should be a proper answer for this, not delete the whole table or database, please if anyone knows the solution then answer it, Thank You in advance – Nikhil Bhardwaj Nov 15 '19 at 04:33
@NikhilBhardwaj did you ever fix it? – Ren Apr 09 '20 at 19:47
1

@Yokhen It can't be one proper way to fix it, but check out this StackOverflow question... https://stackoverflow.com/questions/33681952/django-migration-error-column-does-not-exist may Nexus answer can help you – Nikhil Bhardwaj Apr 11 '20 at 02:57

How to solve UndefinedColumn error in Django

1 Answers1