Simple Django Model (Add to Cart) - django

Question

This is my first Django project and I am trying to implement add-to-cart features.
What changes should I make in this model so that multiple "Item" can be added into "Order", and also keep track of item quantity?
from django.db import models
from django.utils import timezone
# Create your models here.
class Order(models.Model):
customer = models.ForeignKey('Customer')
ordered_item = models.ForeignKey('OrderQuantity', on_delete=models.CASCADE, null=True)
address = models.TextField()
created_date = models.DateTimeField(default=timezone.now)
class Customer(models.Model):
first_name = models.CharField(max_length=50)
last_name = models.CharField(max_length=50)
email = models.EmailField()
phone = models.CharField(max_length=50)
def __str__(self):
return self.first_name
class Item(models.Model):
name = models.CharField(max_length=50)
price = models.DecimalField(default=0.00, max_digits=100, decimal_places=2)
description = models.TextField(null=True)
summary = models.TextField(null=True)
type = models.CharField(max_length=50, null=True)
brand = models.CharField(max_length=50, null=True)
weight = models.DecimalField(default=0.00, max_digits=100, decimal_places=3)
picture = models.ImageField(null=True, upload_to='images/')
created_date = models.DateTimeField(default=timezone.now)
def __str__(self):
return self.name
class OrderQuantity(models.Model):
product = models.ForeignKey('Item')
quantity = models.PositiveIntegerField()

Answer 1

You need to create ManyToManyField in Order Model
class Order(models.Model):
customer = models.ForeignKey('Customer')
ordered_item = models.ForeignKey('OrderQuantity', on_delete=models.CASCADE, null=True)
address = models.TextField()
created_date = models.DateTimeField(default=timezone.now)
items = models.ManyToManyField(Item)
Then you can add items to order in this way:
someorder.items.add(someItem)

Answer 2

Use ManyToManyField in your Item Model
class Item(models.Model):
orders = models.ManyToManyField(Order)
---
So one item have many orders. You can access it by order.item_set or item.orders

Answer 3

It depends on what your Item model is.
If Item is contains a type of product - you may want to use many-to-many field in your Order model, like so:
class Order(models.Model):
...
items = models.ManyToManyField(Item)
...
If Item describes one real item (not type of items), the proper way would be using ForeignKey in your Item model:
class Item(models.Model):
...
order = models.ForeignKey(Order)
...