🔌 Connecting FastAPI to MySQL

Now that our database is fully set up, it’s time to connect our FastAPI backend to MySQL.

This is a major backend milestone — we’re officially moving from SQLite (development) to a production-style MySQL database.

📦 Step 1: Install the Required Dependency

<aside> 💡

Make sure Virtual Environment is active and You are in TodoApp

</aside>

To connect FastAPI (via SQLAlchemy) to MySQL, we need a driver.

Run:

pip install pymysql

We are installing PyMySQL, which allows Python to communicate with MySQL.

Once installed, you're ready to update your configuration.

🗂️ Step 2: Update database.py

Open your database.py file.

We are replacing SQLite with MySQL.

🔄 Change the Database URL

From (SQLite):

SQLALCHEMY_DATABASE_URL = 'sqlite:///./todosapp.db'

To (MySQL):

SQLALCHEMY_DATABASE_URL = 'mysql+pymysql://root:test1234!@127.0.0.1:3306/TodoApplicationDatabase'

Let’s break this down:

• mysql+pymysql → Database type + driver

• root → Username

• test1234! → Password (your passoword)

• 127.0.0.1:3306 → Local machine + default MySQL port

• TodoApplicationDatabase → Our schema name

This tells SQLAlchemy to connect to our MySQL database instead of SQLite.

⚙️ Step 3: Update create_engine

Previously (for SQLite), we had:

engine = create_engine(SQLALCHEMY_DATABASE_URL, connect_args={'check_same_thread': False})

The check_same_thread argument is required only for SQLite.

Since we are now using MySQL, remove it:

engine = create_engine(SQLALCHEMY_DATABASE_URL)

Much cleaner. ✅

🚀 Step 4: Start the Application

Open your terminal and run:

uvicorn main:app --reload

Now your FastAPI backend is connected to MySQL.

🧪 Step 5: Test the Connection

👤 Create two User

Go to your browser → Swagger UI → Create a user.

Click Execute.

You should see:

• Status Code → 201

• Response Body → null

This means the request succeeded.

{
	"username": "codeveda",
	"email": "codeveda@gmail.com",
	"first_name": "code",
	"last_name": "veda",
	"password": "test123",
	"role": ""
}
{
	"username": "testuser",
	"email": "test@gmail.com",
	"first_name": "test",
	"last_name": "user",
	"password": "test123",
	"role": ""
}

🔎 Verify Users

Open MySQL Workbench and run:

SELECT * FROM users;

You should now see two records inside your MySQL database.

🎉 That confirms FastAPI is writing directly to MySQL.

📝 Verify Todos

Now check todos:

SELECT * FROM todos;

You’ll see:

No records yet.

Perfect.

✅ Create a Todo

Go back to your browser and create a todo.

Click Execute → You’ll get:

• Status Code → 201

• Response Body → null

Now return to MySQL and run:

SELECT * FROM todos;

You should now see your new todo record.