Table of Contents
- Introduction
- Prerequisites
- Installation
- Creating a FastAPI App
- Defining Routes
- Creating Models
- Handling Requests and Responses
- Running the App
- Conclusion
Introduction
In this tutorial, you will learn how to build high-performance web applications using Python and FastAPI. FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.7+ based on standard Python type hints. By the end of this tutorial, you will be able to create a basic web app with routes, models, and request handling using FastAPI.
Prerequisites
To follow along with this tutorial, you should have the following:
- Basic knowledge of Python programming language
- Python 3.7 or higher installed on your machine
- Basic understanding of web development concepts
Installation
Before we start building our FastAPI app, let’s make sure we have FastAPI and other necessary dependencies installed.
You can install FastAPI and other dependencies using the following command:
pip install fastapi uvicorn
Creating a FastAPI App
To create a FastAPI app, we need to create a new Python file. Let’s call it main.py. Open your favorite text editor and create the main.py file.
Now, let’s import the necessary modules and create our FastAPI app: ```python from fastapi import FastAPI
app = FastAPI()
``` ## Defining Routes
Routes define the endpoints or URLs for your web application. Let’s create a simple route that returns a “Hello, World!” message.
To define a route, we use the @app.route() decorator and specify the HTTP method and the route URL pattern. Inside the decorated function, we can define the logic for that route.
python
@app.get("/")
def read_root():
return {"message": "Hello, World!"}
Here, we defined a GET request route for the root URL (“/”). The function read_root() returns a JSON response with the message “Hello, World!”.
Creating Models
Models in FastAPI are used to define the structure and validation of data transmitted by your web application. Let’s create a simple model for a user. ```python from pydantic import BaseModel
class User(BaseModel):
name: str
age: int
email: str
``` Here, we imported `BaseModel` from the `pydantic` module and created a `User` model with three fields: `name`, `age`, and `email`.
Handling Requests and Responses
FastAPI provides built-in support for handling request data and generating responses. Let’s modify our route to accept a request body and return a personalized message.
python
@app.post("/greet")
def greet(user: User):
return {"message": f"Hello, {user.name}!"}
In the modified route, we changed the HTTP method to POST and added a user parameter of type User. FastAPI will automatically parse the request body into a User object. We can then access the fields of the User object, in this case, the name field, to personalize the greeting message.
Running the App
To run the FastAPI app, we need to use a server. FastAPI recommends using Uvicorn. Let’s start the server and run our app.
uvicorn main:app --reload
Here, main refers to the main.py file, and app is the instance of the FastAPI app we created.
Once the server is running, you can access your app at http://localhost:8000/ in your web browser. You should see the “Hello, World!” message or use an API testing tool like Postman to test the greet route with a JSON payload.
Conclusion
In this tutorial, you learned how to build high-performance web applications using Python and FastAPI. We covered the basics of creating a FastAPI app, defining routes, creating models, handling requests and responses, and running the app. FastAPI offers many more features and options for building robust web applications, so make sure to explore their official documentation for more advanced usage.
By combining the power of Python and FastAPI, you can build efficient and scalable web apps in no time!
Happy coding!