mre.py
```
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from db import db

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

@app.middleware("http")
async def add_process_time_header(request, call_next):
    if db.is_closed():
        db.connect()

    response = await call_next(request)

    return response

@app.get("/")
async def root():
    return {"message": f"Hello World!"}
```

db.py
```
import os
from dotenv import load_dotenv
from peewee import MySQLDatabase

load_dotenv()

username = os.getenv('USERNAME')
password = os.getenv('PASSWORD')
hostname = os.getenv('HOSTNAME')
database = os.getenv('DATABASE')

DATABASE_URL = "mysql://{username}:{password}@{host}/{db_name}"

db = MySQLDatabase(
    database, user=username,
    password=password, host=hostname, port=3306
)
```