To create modern and efficient APIs using Python, FastAPI is recommended; it is based on standard Python type prompts and can automatically generate documents, with excellent performance. After installing FastAPI and ASGI server uvicorn, you can write interface code. By defining routes, writing processing functions, and returning data, APIs can be quickly built. FastAPI supports a variety of HTTP methods and provides an automatically generated Swagger UI and ReDoc document system. URL parameters can be captured through path definition, while query parameters can be implemented by setting default values ??for function parameters. The rational use of Pydantic models can help improve development efficiency and accuracy.
Want to use Python to make a modern and efficient API? FastAPI is a good choice. It is based on standard Python type prompts, can automatically generate documents, and has good performance, making it suitable for back-end services. The following sections are all about what you need to know most when you get started.

Install FastAPI and Uvicorn
To start using FastAPI, you must first install it and an ASGI server. It is recommended to use uvicorn
, which is the default development server for FastAPI.
You can install it like this:

-
pip install fastapi
-
pip install uvicorn
After installing, you can write the first interface. It will be more convenient to add --reload
(automatically restart in the development environment) when starting.
Write a simple API interface
Create a new Python file, such as main.py
, and then try writing a few lines:

from fastapi import FastAPI app = FastAPI() @app.get("/") def read_root(): return {"Hello": "World"}
Save and run:
uvicorn main:app --reload
Open the browser and visit http://ipnx.cn/link/596239013dbdab4591cefef9be5a5f58 to see the returned JSON. This example is simple, but has shown the most basic structure of FastAPI: defining routes, writing processing functions, and returning data.
How to use automatically generated documents?
A highlight of FastAPI is its own document system. After running, visit directly:
- Swagger UI: http://ipnx.cn/link/596239013dbdab4591cefef9be5a5f58/docs
- ReDoc: http://ipnx.cn/link/596239013dbdab4591cefef9be5a5f58/redoc
These two pages will automatically generate API documentation based on your code. For example, if you add a POST interface with parameters, the corresponding input boxes and examples will automatically appear in the document.
There is no need to write additional comments to have documents, but if you add some description information, the interface will look clearer.
How to deal with routing and request parameters?
FastAPI supports various HTTP methods, such as .get()
, .post()
, .put()
, and .delete()
, which can correspond to different URLs.
The URL parameters can be written like this:
@app.get("/items/{item_id}") def read_item(item_id: int): return {"item_id": item_id}
Querying parameters is also very simple, just add the default value to the function parameters:
@app.get("/search") def search_items(q: str = None, limit: int = 10): return {"query": q, "limit": limit}
Call /search?q=book&limit=5
in this way and you can get the corresponding parameters.
Basically that's it. When you first started, you can figure out these pieces and you can write a decent API. The type prompt is not complicated but easy to ignore. Don't just write it as str
or int
. Use Pydantic models rationally can save you a lot of debugging time.
The above is the detailed content of Python FastAPI tutorial. For more information, please follow other related articles on the PHP Chinese website!

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