Python ORM example application
This SQLAlchemy ORM example, running on Python, implements a basic REST API server for an e-commerce application scenario. Database access in this application is managed through SQL Alchemy ORM.
The source for this application can be found in the python/sqlalchemy
directory of Yugabyte's Using ORMs with YugabyteDB GitHub repository.
Prerequisites
This tutorial assumes that you have:
-
YugabyteDB up and running. Download and install YugabyteDB by following the steps in Quick start.
-
Python 3 is installed
-
the Python packages (dependencies) : SQLAlchemy (
SQLAlchemy
), psycopg2 (psycopg2-binary
) and JSONpickle (jsonpickle
) installed:To install these three packages, run the following command:
$ pip3 install psycopg2-binary sqlalchemy jsonpickle
Clone the "orm-examples" repository
Clone the Yugabyte orm-examples
repository by running the following command.
$ git clone https://github.com/YugabyteDB-Samples/orm-examples.git
Set up the database connection
Update the database settings in the src/config.py
file to match the following. If YSQL authentication is enabled, add the password (default for the yugabyte
user is yugabyte
).
import logging
listen_port = 8080
db_user = 'yugabyte'
db_password = 'yugabyte'
database = 'ysql_sqlalchemy'
schema = 'ysql_sqlalchemy'
db_host = 'localhost'
db_port = 5433
logging.basicConfig(
level=logging.INFO,
format="%(asctime)s:%(levelname)s:%(message)s"
)
Start the REST API server
Run the following Python script to start the server.
python3 ./src/rest-service.py
The REST API server will start and listen for your requests at http://localhost:8080
.
Send requests to the application
Create 2 users.
$ curl --data '{ "firstName" : "John", "lastName" : "Smith", "email" : "jsmith@example.com" }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/users
$ curl --data '{ "firstName" : "Tom", "lastName" : "Stewart", "email" : "tstewart@example.com" }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/users
Create 2 products.
$ curl \
--data '{ "productName": "Notebook", "description": "200 page notebook", "price": 7.50 }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/products
$ curl \
--data '{ "productName": "Pencil", "description": "Mechanical pencil", "price": 2.50 }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/products
Create 2 orders.
$ curl \
--data '{ "userId": "2", "products": [ { "productId": 1, "units": 2 } ] }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/orders
$ curl \
--data '{ "userId": "2", "products": [ { "productId": 1, "units": 2 }, { "productId": 2, "units": 4 } ] }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/orders
Query results
Using the YSQL shell
$ ./bin/ysqlsh
ysqlsh (11.2)
Type "help" for help.
yugabyte=#
yugabyte=# SELECT count(*) FROM users;
count
-------
2
(1 row)
yugabyte=# SELECT count(*) FROM products;
count
-------
2
(1 row)
yugabyte=# SELECT count(*) FROM orders;
count
-------
2
(1 row)
Using the REST API
$ curl http://localhost:8080/users
{
"content": [
{
"userId": 2,
"firstName": "Tom",
"lastName": "Stewart",
"email": "tstewart@example.com"
},
{
"userId": 1,
"firstName": "John",
"lastName": "Smith",
"email": "jsmith@example.com"
}
],
...
}
$ curl http://localhost:8080/products
{
"content": [
{
"productId": 2,
"productName": "Pencil",
"description": "Mechanical pencil",
"price": 2.5
},
{
"productId": 1,
"productName": "Notebook",
"description": "200 page notebook",
"price": 7.5
}
],
...
}
$ curl http://localhost:8080/orders
{
"content": [
{
"orderTime": "2019-05-10T04:26:54.590+0000",
"orderId": "999ae272-f2f4-46a1-bede-5ab765bb27fe",
"user": {
"userId": 2,
"firstName": "Tom",
"lastName": "Stewart",
"email": "tstewart@example.com"
},
"userId": null,
"orderTotal": 25,
"products": []
},
{
"orderTime": "2019-05-10T04:26:48.074+0000",
"orderId": "1598c8d4-1857-4725-a9ab-14deb089ab4e",
"user": {
"userId": 2,
"firstName": "Tom",
"lastName": "Stewart",
"email": "tstewart@example.com"
},
"userId": null,
"orderTotal": 15,
"products": []
}
],
...
}