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Ecommerce API - ScyllaDB & FastAPI sample application

This is a sample ecommerce application built with ScyllaDB and FastAPI.

Prerequisites

Get started

Clone the repository:

git clone https://github.com/zseta/shopping-cart
cd shopping-cart

Create database schema

Connect to your ScyllaDB Cloud cluster using CQLSH and create the schema:

cqlsh -u scylla -p <YOUR_PASSWORD> -f schema.cql xxxx.xxxx.xxxx.clusters.scylla.cloud

Set up API server

Create a new virtual environment:

virtualenv env
source env/bin/activate

Install Python requirements (FastAPI with Uvicorn server and ScyllaDB driver):

pip install fastapi "uvicorn[standard]" scylla-driver requests

Modify config.py to match your database credentials:

HOST="node-0.aws-us-east-1.xxxx.clusters.scylla.cloud"
USER="scylla"
PASSWORD="xxxxxx"
DATACENTER="AWS_US_EAST_1"
KEYSPACE="ecommerce"

Run the server:

uvicorn main:app --reload

Visit API docs: http://127.0.0.1:8000/docs

fast api docs

Generate sample data

Insert products to the database:

cqlsh <ip_address>
COPY ecommerce.product (id, img, name, price) FROM 'product.csv' with HEADER = TRUE;

Generate user interactions (adding products to cart, checkout):

  1. Run the API server: 
    uvicorn main:app
  2. Run the python script: 
    python generate_requests.py
    Shopping started - User(6773b120-8499-4196-9df8-2c4a60b6f1ac) 
(1) Added to cart: abe0e6dc-6ad1-4c3e-8127-80c6176ce99a 
(2) Added to cart: ee9b125d-c92f-4555-bdb3-35aa260b6f91 
(3) Added to cart: 2bf36d87-9b36-4bd3-a44a-8d167e189ce6 
(4) Added to cart: 0c38b0c8-a792-4128-bff9-64c527366202 
(5) Added to cart: 609ed832-e565-4f46-830b-5fabc120e1d4 
Checkout completed (5 items)! 
-----
(1) Added to cart: e8ce5e13-0a7e-4e6e-8858-252f5b1cb1db 
(2) Added to cart: 3a33f31b-b37c-413e-81a5-1f4b42cedcf6 
(3) Added to cart: ffa5f74c-26f2-4342-a6f4-ee2338dd205f 
(4) Added to cart: ef281712-2169-49e4-880a-8da503b0b6de 
(5) Added to cart: 1e8abb0c-f558-433c-a8c8-e029f12c0d7d 
(6) Added to cart: 609ed832-e565-4f46-830b-5fabc120e1d4 
Checkout completed (6 items)! 
-----
(1) Added to cart: 0015b10c-0842-4796-840a-2e43a6a719d3 
(2) Added to cart: abe0e6dc-6ad1-4c3e-8127-80c6176ce99a 
(3) Added to cart: 0c38b0c8-a792-4128-bff9-64c527366202 
Checkout completed (3 items)! 
-----
    You can run this script from multiple terminals to generate more data.

Change Data Capture (CDC)

Change Data Capture (CDC) is a ScyllaDB feature that records every change (insert, update, delete) that happens in your table. CDC provides real-time and historical insights into user behavior, product performance, and activity.

Here are some example CDC queries that can be useful for an ecommerce application:

How many times do users add more than 2 of the same product to the cart?

SELECT count(*) 
FROM ecommerce.cart_items_scylla_cdc_log 
WHERE "cdc$operation"= 2 AND product_quantity > 2
ALLOW FILTERING;

How many carts contain a particular product?

FROM ecommerce.cart_items_scylla_cdc_log
WHERE "cdc$operation"= 2 AND product_id = dc87a43f-53b2-48a2-9003-2654345b6647
ALLOW FILTERING;

Notice how in both cases we put "cdc$operation"= 2 in the where clause. This is because if the operation is 2 that means it was an INSERT operation. Learn more about ScyllaDB CDC.