With FastAPI, you can easily validate input data using Pydantic’s schema system, automatically convert between JSON and Python objects, and document your APIs with OpenAPI. Additionally, FastAPI provides interactive documentation web interfaces directly for ease of use.
FastAPI is designed to be fast by leveraging the power of asynchronous processing from the ground up. It clgoals to be one of the fastest Python web frameworks today, making it suitable for high-traffic web applications that must handle real-time data. Moreover, FastAPI’s syntax is concise and expressive, which makes writing code cheaper to maintain.
To use FastAPI, you can install it using pip: `pip install fastapi`. Once installed, you can create a new Python file with the following content:
# Importing necessary modules
from fastapi import FastAPI # Importing FastAPI module for creating web applications
import uvicorn # Importing uvicorn module for running the application
# Creating an instance of FastAPI
app = FastAPI() # Creating an instance of FastAPI class and assigning it to the variable 'app'
# Defining a route for the root endpoint
@app.get("/") # Using the decorator 'app.get' to define a route for the root endpoint
async def read_root(): # Defining an asynchronous function for handling requests to the root endpoint
return {"Hello": "World"} # Returning a dictionary as the response with the key "Hello" and value "World"
# Running the application
if __name__ == "__main__": # Checking if the script is being run directly
uvicorn.run(app, host="0.0.0.0", port=8000) # Running the application using uvicorn with the specified host and port
This code creates a new FastAPI instance and defines an endpoint at the root URL (`/`) that returns a simple JSON response with “Hello” and “World”. To run this example, save it as `main.py`, navigate to its directory in your terminal or command prompt, and execute:
# This code creates a new FastAPI instance
# and defines an endpoint at the root URL (`/`)
# that returns a simple JSON response with "Hello" and "World".
# Import the necessary modules for creating a FastAPI instance
from fastapi import FastAPI
# Import the necessary modules for creating a JSON response
from fastapi.responses import JSONResponse
# Create a new FastAPI instance
app = FastAPI()
# Define an endpoint at the root URL (`/`)
@app.get("/")
# Create a function that returns a simple JSON response with "Hello" and "World"
def hello_world():
# Create a dictionary with the desired response
response = {"message": "Hello World"}
# Return the response as a JSON object
return JSONResponse(content=response)
# To run this example, save it as `main.py`,
# navigate to its directory in your terminal or command prompt,
# and execute:
# python main.py
This will start the FastAPI server on port 8000, which you can access using a web browser at http://localhost:8000/. You should see the following output in your terminal or command prompt:
# This line starts the FastAPI server on port 8000 and provides the URL to access it.
# The server can be accessed using a web browser at http://localhost:8000/.
# The server will display its output in the terminal or command prompt.
# This line indicates that Uvicorn is running on the specified URL.
# Uvicorn is a lightning-fast ASGI server implementation, used to run the FastAPI server.
# The URL is the local IP address (127.0.0.1) and the port number (8000).
# This line provides instructions to quit the server by pressing CTRL+C.
# This is a common command used to stop a running process in the terminal or command prompt.
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO: 127.0.0.1:8000 (Press CTRL+C to quit)
To learn more about FastAPI, you can check out its official documentation at https://fastapi.tiangolo.com/.