Create REST API to perform CRUD Operations using FastAPI and MySQL

In this tutorial, you will learn how to create REST API to perform CRUD operations using FastAPI with MySQL.

Follow the steps below to complete this tutorial:

1. Start by creating a new project folder:

mkdir sample_fastapi_mongodb_app

2. Navigate to your newly created project folder:

cd sample_fastapi_mongodb_app

3. Create a virtual environment inside the project root directory using the following command:
Windows:

py -m venv env

Unix/macOs:

python3 -m venv env

4. Activate the virtual environment using the command:
Windows:

.\env\Scripts\activate

Unix/macOs:

source env/bin/activate

5. Install FastAPI:

pip install fastapi

6. Install uvicorn:

pip install uvicorn

7. Install pydantic to validate email:

pip install pydantic[email]

8. Install PyMySQL. It is a pure Python MySQL client library:

pip install PyMySQL

9. Install SQLAlchemy. It is a Python SQL Object Relational Mapper that provides complete SQL capability and flexibility to application developers. It provides a collection of well-known enterprise-level persistence patterns for fast and high-performance database access:

pip install SQLAlchemy

10. Create a database using the following MySQL command:

CREATE DATABASE my_test_db;

11. Create product table using the following MySQL command:

USE my_test_db;
CREATE TABLE IF NOT EXISTS product(
	id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(1024),
    price BIGINT DEFAULT 0,
    is_available BOOLEAN DEFAULT FALSE,
    seller_email VARCHAR(512),
    deleted BOOLEAN DEFAULT FALSE,
    created_by INT NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_by INT NULL,
    updated_at TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE = INNODB;

12. Create a directory structure for your FastAPI project. A common structure should look like this:

├── sample_fastapi_mysql_app
│   │── env
│   │── db
│   │    └── database.py
│   │
│   ├── endpoints
│   │     └── product.py
│   │     └── user.py
│   │
│   ├── models
│   │     └── models.py
│   │     └── request.py
│   │     └── response.py
│   │
│   ├── routes
│   │     └── api.py
│   │
│   ├── __init__.py
│   ├── main.py

13. Create a model file named models.py in the src/models directory:

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, INTEGER, String, TIMESTAMP, BIGINT, BOOLEAN, text

Base = declarative_base()

class Product(Base):
    __tablename__ = "product"
    id = Column(INTEGER, primary_key=True)
    name = Column(String(1024), nullable=False)
    price = Column(BIGINT)
    is_available = (Column(BOOLEAN, default=True))
    seller_email = (Column(String(512), nullable=True))
    deleted = (Column(BOOLEAN, default=False))
    created_by = Column(INTEGER, nullable=True)
    created_at = Column(TIMESTAMP, nullable=False,
                        server_default=text("CURRENT_TIMESTAMP"))
    updated_by = Column(INTEGER, nullable=True)
    updated_at = Column(TIMESTAMP, nullable=True,
                        server_default=text("CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP"))


class User(Base):
    __tablename__ = "user"
    id = Column(INTEGER, primary_key=True)
    first_name = Column(String(512), nullable=False)
    last_name = Column(String(512), nullable=False)
    deleted = (Column(BOOLEAN, default=False))
    created_by = Column(INTEGER, nullable=True)
    created_at = Column(TIMESTAMP, nullable=False,
                        server_default=text("CURRENT_TIMESTAMP"))
    updated_by = Column(INTEGER, nullable=True)
    updated_at = Column(TIMESTAMP, nullable=True,
                        server_default=text("CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP"))

14. Create a request.py file in the src/models directory:

from pydantic import BaseModel, EmailStr, Field
from typing import Optional


class ProductRequest(BaseModel):
    name: str = Field(
        None, title="Product Name", max_length=1000
    )
    price: float = Field(..., gt=0,
                         description="Price of the product")
    is_available: bool = Field(
        False, description="Value must be either True or False")
    seller_email: EmailStr = Field(None, title="Seller Email")
    created_by: int = Field(None, title="User Id")


class ProductUpdateRequest(BaseModel):
    product_id: int
    name: str = Field(
        None, title="Product Name", max_length=1000
    )
    price: float = Field(..., gt=0,
                         description="The price must be greater than zero")
    is_available: bool = Field(
        False, description="Value must be either True or False")
    seller_email: Optional[EmailStr] = Field(None, title="Updater Email")
    updated_by: int = Field(None, title="Updater Id")

15. Create a response.py file in the src/models directory:

def Response(data, code, message, error):
    return {
        "data": data,
        "code": code,
        "message": message,
        "error": error
    }

16. Create a file named database.py in the db directory:

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

db_host = "localhost"
db_port = "3306"
db_username = "your-username"
db_password = "your-password"
db_name = "test_database"

MYSQL_URL = "mysql+pymysql://{db_username}:{db_password}@{db_host}:{db_port}/{db_name}?charset=utf8"
POOL_SIZE = 20
POOL_RECYCLE = 3600
POOL_TIMEOUT = 15
MAX_OVERFLOW = 2
CONNECT_TIMEOUT = 60

class Database():
    def __init__(self) -> None:
        self.connection_is_active = False
        self.engine = None

    def get_db_connection(self):
        if self.connection_is_active == False:
            connect_args = {"connect_timeout":CONNECT_TIMEOUT}
            try:
                self.engine = create_engine(MYSQL_URL, pool_size=POOL_SIZE, pool_recycle=POOL_RECYCLE,
                        pool_timeout=POOL_TIMEOUT, max_overflow=MAX_OVERFLOW, connect_args=connect_args)
                return self.engine
            except Exception as ex:
                print("Error connecting to DB : ", ex)
        return self.engine

    def get_db_session(self,engine):
        try:
            Session = sessionmaker(bind=engine)
            session = Session()
            return session
        except Exception as ex:
            print("Error getting DB session : ", ex)
            return None

17. Create a file named product_service.py in the src/endpoints directory:

from fastapi import APIRouter
from models.request import ProductRequest, ProductUpdateRequest
from models.response import Response
from models.models import Product
from db.database import Database
from sqlalchemy import and_, desc

# APIRouter creates path operations for product module
router = APIRouter(
    prefix="/products",
    tags=["Product"],
    responses={404: {"description": "Not found"}},
)

database = Database()
engine = database.get_db_connection()


@router.post("/add", response_description="Product data added into the database")
async def add_product(product_req: ProductRequest):
    new_product = Product()
    new_product.name = product_req.name
    new_product.price = product_req.price
    new_product.seller_email = product_req.seller_email
    new_product.is_available = product_req.is_available
    new_product.created_by = product_req.created_by
    new_product_id = None
    session = database.get_db_session(engine)
    session.add(new_product)
    session.flush()
    # get id of the inserted product
    session.refresh(new_product, attribute_names=['id'])
    data = {"product_id": new_product.id}
    session.commit()
    session.close()
    return Response(data, 200, "Product added successfully.", False)


@router.put("/update")
async def update_product(product_update_req: ProductUpdateRequest):
    product_id = product_update_req.product_id
    session = database.get_db_session(engine)
    try:
        is_product_updated = session.query(Product).filter(Product.id == product_id).update({
            Product.name: product_update_req.name, Product.price: product_update_req.price,
            Product.seller_email: product_update_req.seller_email,
            Product.is_available: product_update_req.is_available,
            Product.updated_by: product_update_req.updated_by
        }, synchronize_session=False)
        session.flush()
        session.commit()
        response_msg = "Product updated successfully"
        response_code = 200
        error = False
        if is_product_updated == 1:
            # After successful update, retrieve updated data from db
            data = session.query(Product).filter(
                Product.id == product_id).one()

        elif is_product_updated == 0:
            response_msg = "Product not updated. No product found with this id :" + \
                str(product_id)
            error = True
            data = None
        return Response(data, response_code, response_msg, error)
    except Exception as ex:
        print("Error : ", ex)


@router.delete("/{product_id}/delete")
async def delete_product(product_id: str):
    session = database.get_db_session(engine)
    try:
        is_product_updated = session.query(Product).filter(and_(Product.id == product_id, Product.deleted == False)).update({
            Product.deleted: True}, synchronize_session=False)
        session.flush()
        session.commit()
        response_msg = "Product deleted successfully"
        response_code = 200
        error = False
        data = {"product_id": product_id}
        if is_product_updated == 0:
            response_msg = "Product not deleted. No product found with this id :" + \
                str(product_id)
            error = True
            data = None
        return Response(data, response_code, response_msg, error)
    except Exception as ex:
        print("Error : ", ex)


@router.get("/{product_id}")
async def read_product(product_id: str):
    session = database.get_db_session(engine)
    response_message = "Product retrieved successfully"
    data = None
    try:
        data = session.query(Product).filter(
            and_(Product.id == product_id, Product.deleted == False)).one()
    except Exception as ex:
        print("Error", ex)
        response_message = "Product Not found"
    error = False
    return Response(data, 200, response_message, error)


@router.get("/")
async def read_all_products(created_by: str, page_size: int, page: int):
    session = database.get_db_session(engine)
    data = session.query(Product).filter(and_(Product.created_by == created_by, Product.deleted == False)).order_by(
        desc(Product.created_at)).limit(page_size).offset((page-1)*page_size).all()
    return Response(data, 200, "Products retrieved successfully.", False)

18. Create a file named user_service.py in the src/endpoints directory for user API endpoints. We are not saving user data in the database in this example:

from fastapi import APIRouter

# APIRouter creates path operations for product module
router = APIRouter(
    prefix="/users",
    tags=["User"],
    responses={404: {"description": "Not found"}},
)

@router.get("/")
async def read_user():
    return {"name": "John", "email": "john@example.com"}

19. Create api.py file in the routes directory to handle API routing:

from fastapi import APIRouter
from endpoints import product_service, user_service

router = APIRouter()
router.include_router(product_service.router)
router.include_router(user_service.router)

20. Create a main file named main.py in the project's root directory:

import uvicorn
from fastapi.middleware.cors import CORSMiddleware
from fastapi import FastAPI
from routes.api import router as api_router

app = FastAPI()

origins = ["http://localhost:8000"]

app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

app.include_router(api_router)

if __name__ == '__main__':
    uvicorn.run("main:app", host='127.0.0.1', port=8000, log_level="info", reload = True)
    print("running")

21. Run the application:

python main.py

To test the endpoints, go to your browser and open http://localhost:8000/docs. You will see list of APIs that you can test.