1. Introduction to FastAPI
FastAPI is a modern and high-performance web framework for building APIs with Python. It is based on the Starlette framework and the Pydantic library, which provide fast and easy data validation, serialization, and documentation.
Some of the main features of FastAPI are:
- It supports OpenAPI and JSON Schema standards for API documentation and validation.
- It has built-in support for asynchronous I/O and concurrency, which make it suitable for high-performance and scalable applications.
- It has a simple and expressive syntax that makes it easy to define and use API endpoints.
- It has a rich ecosystem of extensions and integrations, such as SQLAlchemy, MongoDB, JWT, Docker, and more.
In this tutorial, you will learn how to install FastAPI and create your first web API endpoint using Python and Uvicorn server. Uvicorn is an ASGI server that runs FastAPI applications and provides high performance and concurrency.
By the end of this tutorial, you will be able to:
- Install FastAPI and Uvicorn using Pip.
- Create a simple Hello World endpoint that returns a JSON response.
- Run and test your endpoint using Uvicorn and a web browser.
Are you ready to get started with FastAPI? Let’s go!
2. Setting up the Environment
Before you can start creating your first web API endpoint with FastAPI, you need to set up your environment with the necessary tools and packages. In this section, you will learn how to install Python and Pip, which are the basic requirements for working with FastAPI. You will also learn how to install FastAPI and Uvicorn, which are the core components of your web application.
Python is a popular and versatile programming language that is widely used for web development, data science, machine learning, and more. Pip is a package manager that allows you to install and manage Python packages from the Python Package Index (PyPI).
FastAPI is a web framework that makes it easy to create web APIs with Python. Uvicorn is an ASGI server that runs FastAPI applications and provides high performance and concurrency.
To install Python and Pip, you can follow the official instructions for your operating system from the Python website. Make sure you have the latest version of Python 3 installed, as FastAPI does not support Python 2.
To install FastAPI and Uvicorn, you can use Pip from your terminal or command prompt. Simply run the following command:
pip install fastapi uvicorn
This will install the latest versions of FastAPI and Uvicorn, along with their dependencies. You can check the installation by running the following commands:
python -c "import fastapi; print(fastapi.__version__)" python -c "import uvicorn; print(uvicorn.__version__)"
You should see the version numbers of FastAPI and Uvicorn printed on your screen. If you encounter any errors, make sure you have Python and Pip installed correctly and try again.
Congratulations, you have successfully set up your environment for FastAPI development! You are now ready to create your first web API endpoint.
2.1. Installing Python and Pip
Python and Pip are the basic requirements for working with FastAPI. Python is a popular and versatile programming language that is widely used for web development, data science, machine learning, and more. Pip is a package manager that allows you to install and manage Python packages from the Python Package Index (PyPI).
To install Python and Pip, you need to follow the official instructions for your operating system from the Python website. Make sure you have the latest version of Python 3 installed, as FastAPI does not support Python 2. You can check your Python version by running the following command in your terminal or command prompt:
python --version
You should see something like this:
Python 3.9.1
If you see a lower version number or an error message, you need to update or install Python 3.
Pip is usually included with Python 3, but you can also check if you have it installed by running the following command:
pip --version
You should see something like this:
pip 21.0.1 from /usr/local/lib/python3.9/site-packages/pip (python 3.9)
If you see an error message or a lower version number, you need to update or install Pip.
Once you have Python and Pip installed, you are ready to install FastAPI and Uvicorn, which are the core components of your web application.
2.2. Installing FastAPI and Uvicorn
FastAPI and Uvicorn are the core components of your web application. FastAPI is a web framework that makes it easy to create web APIs with Python. Uvicorn is an ASGI server that runs FastAPI applications and provides high performance and concurrency.
To install FastAPI and Uvicorn, you can use Pip from your terminal or command prompt. Simply run the following command:
pip install fastapi uvicorn
This will install the latest versions of FastAPI and Uvicorn, along with their dependencies. You can check the installation by running the following commands:
python -c "import fastapi; print(fastapi.__version__)" python -c "import uvicorn; print(uvicorn.__version__)"
You should see the version numbers of FastAPI and Uvicorn printed on your screen. If you encounter any errors, make sure you have Python and Pip installed correctly and try again.
Once you have FastAPI and Uvicorn installed, you are ready to create your first web API endpoint.
3. Creating a Hello World Endpoint
In this section, you will learn how to create your first web API endpoint with FastAPI. A web API endpoint is a URL that accepts and responds to HTTP requests, such as GET, POST, PUT, or DELETE. You can use web API endpoints to expose data and functionality from your web application to other applications or users.
FastAPI makes it easy to define and use web API endpoints with a simple and expressive syntax. You just need to create a FastAPI object, decorate a function with the @app.get() or @app.post() decorator, and specify the path of the endpoint. The function will handle the requests and return the response.
To create a Hello World endpoint, you need to write the following code in a file named main.py:
#import FastAPI
from fastapi import FastAPI
#create a FastAPI object
app = FastAPI()
#define a Hello World endpoint
@app.get("/")
def hello_world():
return {"message": "Hello World"}
This code does the following:
- It imports the FastAPI class from the fastapi module.
- It creates a FastAPI object named app, which is the main entry point of your web application.
- It defines a function named hello_world, which will handle the requests to the root path (“/”) of your web application.
- It decorates the function with the @app.get() decorator, which tells FastAPI that this function is a web API endpoint that accepts GET requests.
- It returns a JSON object with a message key and a value of “Hello World”. This is the response that will be sent to the client.
That’s it! You have created your first web API endpoint with FastAPI. You can now run and test your endpoint using Uvicorn and a web browser.
3.1. Writing the Code
In this section, you will learn how to write the code for your Hello World endpoint with FastAPI. You will use a simple and expressive syntax that allows you to define and use web API endpoints with Python functions.
To write the code for your Hello World endpoint, you need to create a file named main.py in your project folder. You can use any text editor or IDE of your choice, such as Visual Studio Code, PyCharm, or Sublime Text.
In the main.py file, you need to write the following code:
#import FastAPI
from fastapi import FastAPI
#create a FastAPI object
app = FastAPI()
#define a Hello World endpoint
@app.get("/")
def hello_world():
return {"message": "Hello World"}
This code does the following:
- It imports the FastAPI class from the fastapi module.
- It creates a FastAPI object named app, which is the main entry point of your web application.
- It defines a function named hello_world, which will handle the requests to the root path (“/”) of your web application.
- It decorates the function with the @app.get() decorator, which tells FastAPI that this function is a web API endpoint that accepts GET requests.
- It returns a JSON object with a message key and a value of “Hello World”. This is the response that will be sent to the client.
That’s it! You have written the code for your first web API endpoint with FastAPI. You can now run and test your endpoint using Uvicorn and a web browser.
3.2. Running the Server
After writing the code for your Hello World endpoint, you need to run your web application using Uvicorn. Uvicorn is an ASGI server that runs FastAPI applications and provides high performance and concurrency.
To run your web application using Uvicorn, you need to use the following command in your terminal or command prompt:
uvicorn main:app --reload
This command does the following:
- It invokes the uvicorn executable.
- It specifies the name of the file and the FastAPI object to run. In this case, the file is main.py and the object is app.
- It adds the –reload option, which enables auto-reloading of the server when the code changes. This is useful for development purposes, but not for production.
Once you run the command, you should see something like this:
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit) INFO: Started reloader process [1] using statreload INFO: Started server process [3] INFO: Waiting for application startup. INFO: Application startup complete.
This means that your web application is running on your local machine at the address http://127.0.0.1:8000. You can now test your endpoint using a web browser.
3.3. Testing the Endpoint
After running your web application using Uvicorn, you can test your Hello World endpoint using a web browser. A web browser is a software application that allows you to access and view web pages on the internet. You can use any web browser of your choice, such as Google Chrome, Mozilla Firefox, or Microsoft Edge.
To test your Hello World endpoint using a web browser, you need to follow these steps:
- Open your web browser and type the address of your web application in the address bar. In this case, the address is http://127.0.0.1:8000. This is the same address that Uvicorn showed you when you ran your web application.
- Press the enter key or click the go button to send the request to your web application.
- Wait for the response from your web application. You should see a web page with a JSON object that contains the message key and the value of “Hello World”. This is the same response that your hello_world function returned.
Congratulations, you have successfully tested your first web API endpoint with FastAPI! You have created a web application that can accept and respond to HTTP requests, and you have verified that it works as expected.
4. Conclusion and Next Steps
In this tutorial, you have learned how to get started with FastAPI, a modern and high-performance web framework for building APIs with Python. You have learned how to install FastAPI and Uvicorn, how to create a Hello World endpoint, how to run and test your endpoint, and how to write the code for your web application.
FastAPI is a powerful and easy-to-use tool that can help you create web APIs with minimal code and maximum performance. It supports OpenAPI and JSON Schema standards for API documentation and validation, asynchronous I/O and concurrency for scalability, and a simple and expressive syntax for defining and using endpoints.
By following this tutorial, you have taken the first step towards becoming a FastAPI developer. You have gained the basic knowledge and skills that you need to create your own web APIs with FastAPI.
But this is just the beginning. There is much more to learn and explore with FastAPI. Some of the topics that you can dive deeper into are:
- How to use different HTTP methods, such as POST, PUT, or DELETE, to create CRUD (Create, Read, Update, Delete) endpoints.
- How to use path and query parameters, request bodies, and response models to validate and serialize data.
- How to use dependencies, security, and authentication to add functionality and protection to your endpoints.
- How to use databases, background tasks, and middleware to store, process, and manage data.
- How to use extensions and integrations, such as SQLAlchemy, MongoDB, JWT, Docker, and more, to enhance and customize your web application.
You can find more information and resources about FastAPI from the official website, the official tutorial, and the GitHub repository.
We hope you enjoyed this tutorial and found it useful. If you have any questions, feedback, or suggestions, please let us know in the comments section below. Thank you for reading and happy coding!
