Complete Guide on Creating a Python API Using FastAPI

In this tutorial, I will show you step by step how to create a Python API using FastAPI, a modern web framework for building APIs with Python. FastAPI is fast, simple to use, and easy to learn, making it a great choice for building web services or APIs.

Before we begin, make sure you have Python installed on your machine. You can download Python from the official website (https://www.python.org/). Once you have Python installed, you can proceed with the following steps to create your Python API with FastAPI.

Step 1: Create a new Python virtual environment
To keep your project dependencies isolated and organized, it’s a good practice to create a new virtual environment for each project. To create a new virtual environment, open your terminal or command prompt and run the following command:

$ python -m venv myenv

This command will create a new virtual environment named myenv. You can replace myenv with any name you prefer.

Step 2: Activate the virtual environment
Once the virtual environment is created, you need to activate it. To activate the virtual environment, run the following command:

For Windows:

$ source myenv/Scripts/activate

For MacOS or Linux:

$ source myenv/bin/activate

Step 3: Install FastAPI and Uvicorn
Next, you need to install the FastAPI framework and Uvicorn, a lightning-fast ASGI server. To install FastAPI and Uvicorn, run the following command:

$ pip install fastapi uvicorn

Step 4: Create a new Python file for your API
Create a new Python file in your project directory. You can name the file main.py or any other name you prefer. Open the file in your favorite code editor and start building your API.

Step 5: Define your API endpoints
In your main.py file, import FastAPI and create an instance of the FastAPI class. Define your API endpoints using the @app.get() or @app.post() decorators. Here is an example of a simple API endpoint that returns a JSON response:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def read_root():
    return {"message": "Hello, World!"}

Step 6: Run your API using Uvicorn
To run your API, use the Uvicorn ASGI server. In your terminal, navigate to the directory where your main.py file is located and run the following command to start the server:

$ uvicorn main:app --reload

This command tells Uvicorn to run your main.py file with the app instance created using FastAPI. The --reload flag enables automatic reloading of the server when changes are made to your code.

Step 7: Test your API
Once your API is running, open your web browser and go to http://127.0.0.1:8000/ to test your API endpoint. You should see the JSON response returned by your API, like {"message": "Hello, World!"}.

Congratulations! You have now created a Python API using FastAPI. You can further enhance your API by adding more endpoints, handling request parameters, connecting to a database, and much more. FastAPI provides comprehensive documentation that covers all the features and functionalities of the framework. You can refer to the official FastAPI documentation (https://fastapi.tiangolo.com/) for more information and examples.

I hope this tutorial has been helpful in getting you started with building APIs using FastAPI. Happy coding!