IntegrityError Primary Key Invalid in django

Question

Something fixed in Order Class of model. and then, I run migrate. But, it is shown an error as

django.db.utils.IntegrityError: The row in table 'core_order' with primary >key '4' has an invalid foreign key: core_order.billing_address_id contains a >value '1' that does not have a corresponding value in core_address.id.

Models.py

from django.conf import settings
from django.db import models
from django.db.models import Sum
from django.shortcuts import reverse
from django_countries.fields import CountryField

# Create your models here.
CATEGORY_CHOICES = (
    ('SB', 'Shirts And Blouses'),
    ('TS', 'T-Shirts'),
    ('SK', 'Skirts'),
    ('HS', 'Hoodies&Sweatshirts')
)

LABEL_CHOICES = (
    ('S', 'sale'),
    ('N', 'new'),
    ('P', 'promotion')
)


class Item(models.Model):
    title = models.CharField(max_length=100)
    price = models.FloatField()
    discount_price = models.FloatField(blank=True, null=True)
    category = models.CharField(choices=CATEGORY_CHOICES, max_length=2)
    label = models.CharField(choices=LABEL_CHOICES, max_length=1)
    slug = models.SlugField()
    description = models.TextField()
    image = models.ImageField()

    def __str__(self):
        return self.title

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

    def get_add_to_cart_url(self):
        return reverse("core:add-to-cart", kwargs={
            'slug': self.slug
        })

    def get_remove_from_cart_url(self):
        return reverse("core:remove-from-cart", kwargs={
            'slug': self.slug
        })


class OrderItem(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             on_delete=models.CASCADE)
    ordered = models.BooleanField(default=False)
    item = models.ForeignKey(Item, on_delete=models.CASCADE)
    quantity = models.IntegerField(default=1)

    def __str__(self):
        return f"{self.quantity} of {self.item.title}"

    def get_total_item_price(self):
        return self.quantity * self.item.price

    def get_total_discount_item_price(self):
        return self.quantity * self.item.discount_price

    def get_amount_saved(self):
        return self.get_total_item_price() - self.get_total_discount_item_price()

    def get_final_price(self):
        if self.item.discount_price:
            return self.get_total_discount_item_price()
        return self.get_total_item_price()


class Order(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             on_delete=models.CASCADE)
    ref_code = models.CharField(max_length=20)
    items = models.ManyToManyField(OrderItem)
    start_date = models.DateTimeField(auto_now_add=True)
    ordered_date = models.DateTimeField()
    ordered = models.BooleanField(default=False)
    billing_address = models.ForeignKey(
        'BillingAddress', on_delete=models.SET_NULL, blank=True, null=True)
    payment = models.ForeignKey(
        'Payment', on_delete=models.SET_NULL, blank=True, null=True)
    coupon = models.ForeignKey(
        'Coupon', on_delete=models.SET_NULL, blank=True, null=True)
    being_delivered = models.BooleanField(default=False)
    received = models.BooleanField(default=False)
    refund_requested = models.BooleanField(default=False)
    refund_granted = models.BooleanField(default=False)

    '''
    1. Item added to cart
    2. Adding a BillingAddress
    (Failed Checkout)
    3. Payment
    4. Being delivered
    5. Received
    6. Refunds
    '''

    def __str__(self):
        return self.user.username

    def get_total(self):
        total = 0
        for order_item in self.items.all():
            total += order_item.get_final_price()
        if self.coupon:
            total -= self.coupon.amount
        return total


class BillingAddress(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             on_delete=models.CASCADE)
    street_address = models.CharField(max_length=100)
    apartment_address = models.CharField(max_length=100)
    country = CountryField(multiple=False)
    zip = models.CharField(max_length=100)

    def __str__(self):
        return self.user.username


class Payment(models.Model):
    stripe_charge_id = models.CharField(max_length=50)
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             on_delete=models.SET_NULL, blank=True, null=True)
    amount = models.FloatField()
    timestamp = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.user.username


class Coupon(models.Model):
    code = models.CharField(max_length=15)
    amount = models.FloatField()

    def __str__(self):
        return self.code


class Refund(models.Model):
    order = models.ForeignKey(Order, on_delete=models.CASCADE)
    reason = models.TextField()
    accepted = models.BooleanField(default=False)
    email = models.EmailField()

    def __str__(self):
        return f"{self.pk}"

i undo to Previous code, but primary key error is still showing when i migrate

Answer 1

Deleted all the migration records except __init__.py file.

Also Deleted the db.sqlite3 file.

And Then, run following commands

python manage.py makemigrations core
python manage.py migrate

Hope this Help

Answer 2

For example, given an orders table and a customers table, if you create a column orders.customer_id that references the customers.id primary key:

Each value that is inserted or updated in orders.customer_id must exactly match a value in customers.id , or be NULL.

Values in customers.id that are referenced by orders.customer_id cannot be deleted or updated, unless you have cascading actions. However, values of customers.id that are not present in orders.customer_id can be deleted or updated.

If you made a mistake in a migration, the easiest way to undo it is to do the migration backwards. For example, if you just created the 0003 migration:

manage.py migrate your_app 0002
rm your_app/migrations/0003_*.py

You can also change the state of migrations without actually running them if you have an error:

manage.py migrate --fake your_app 0002

fix your database manually

rm your_app/migrations/0003_*.py

Another way we can solve this problem on sqlite is:

To remove the addresses table, you have to:

Open sqlite.exe program a dbshell terminal will be opened, you see all the tables and schema there by following command:

.databases ( shows all the databases)

.schema * 

the ".schema" command shows the schema for all attached databases. If you only want to see the schema for a single database (perhaps "main") then you can add an argument to ".schema" to restrict its output:

.schema main.* 

Now you can see the database and database index giving trouble. Now you need to: Disable foreign key constraints. Drop the addresses table. Update the address_id in the people table to NULL values. Enable the foreign key constraints.

PRAGMA foreign_keys = OFF;

DROP TABLE addresses;

UPDATE people
SET address_id = NULL;

PRAGMA foreign_keys = ON;

On the above example, you can assume there are two tables People and Addresses. People table uses Address ID as foreign_key from address. Due to foreign_key constraints, we were unable to delete the table or we were unable to modify the table.