FastAPI 备忘清单

FastAPI 是一个用于构建 API 的现代、快速（高性能）的 web 框架，使用 Python 3.6+ 并基于标准的 Python 类型提示。Python: 3.9.5 FastAPI: 0.103.1

入门

最小程序

下面代码会直接启动http服务，也可以使用 uvicorn main:app --reload

from fastapi import FastAPI
import uvicorn

app = FastAPI()

# http://127.0.0.1:8000/
@app.get("/")
async def root():
    return {"message": "Hello World"}

if __name__ == '__main__':
    uvicorn.run(app='main:app', reload=True)

路径参数

最基本的路径参数 

# http://127.0.0.1:8000/items/1
@app.get("/items/{item_id}")
async def read_item(item_id):
    return {"item_id": item_id} # item_id自定义

多个路径参数 

# http://127.0.0.1:8000/items/1/2
@app.get("/items/{item_id}/{user_id}")
async def read_item(item_id, user_id):
    return {"item_id": item_id, "user_id": user_id}

有类型的路径参数 

# http://127.0.0.1:8000/items/1
@app.get("/items/{item_id}")
async def read_item(item_id: int):
    return {"item_id": item_id}

文件路径参数 

# http://127.0.0.1:8000/file//home/my/my.txt
@app.get("/file/{file_path:path}")
async def read_item(file_path):
    return {"file_path": file_path}

查询参数

带默认值的查询参数 

# http://127.0.0.1:8000/items/?skip=0&limit=2
fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]
@app.get("/items/")
async def read_item(skip: int = 0, limit: int = 10):
    return fake_items_db[skip: skip + limit]

可选查询参数 

# http://127.0.0.1:8000/items/1?q=admin
from typing import Union
@app.get("/items/{item_id}")
async def read_item(item_id: str, q: Union[str, None] = None):
    if q:
        return {"item_id": item_id, "q": q}
    return {"item_id": item_id}

多路径多查询参数 

# http://127.0.0.1:8000/users/1/items/2
# or 
# http://127.0.0.1:8000/users/1/items/2?q=query&short=true
@app.get("/users/{user_id}/items/{item_id}")
async def read_user_item(
        user_id: int, item_id: str, q: Union[str, None] = None, short: bool = False
):
    item = {"item_id": item_id, "owner_id": user_id}
    if q:
        item.update({"q": q})
    if not short:
        item.update(
            {"description": "This is an amazing item that has a long description"}
        )
    return item

必需查询参数 

# http://127.0.0.1:8000/items/123?needy=yes
@app.get("/items/{item_id}")
async def read_user_item(item_id: str, needy: str):
    item = {"item_id": item_id, "needy": needy}
    return item

请求体 

from pydantic import BaseModel
from typing import Union
class Item(BaseModel):
    name: str = '小明'
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
@app.post("/items/")
async def create_item(item: Item):
    print(item.name)
    return item

调用 

curl -X 'POST' \
  'http://127.0.0.1:8000/items/' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "name": "小明",
  "description": "string",
  "price": 0,
  "tax": 0
}'

查询参数和字符串校验 

from fastapi import Query
@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=None, max_length=50)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

参数列表

参数 含义 类型
default 默认值 任意类型或...
max_length 最大长度 int
min_length 最小长度 int
pattern 正则匹配 string
alias 别名参数 string
deprecated 准备弃用参数 bool

多个相同的查询参数 

# http://127.0.0.1:8000/items/?q=foo&q=bar
@app.get("/items/")
async def read_items(q: Union[List[str], None] = Query(default=None)):
    query_items = {"q": q}
    return query_items

路径参数和数值校验

Path用法基本和Query相同，参考：FastAPI官方文档

导入 Path 

from fastapi import FastAPI, Path, Query
from typing_extensions import Annotated

声明元数据 

@app.get("/items/{item_id}")
async def read_items(
    item_id: Annotated[int, Path(title="The ID of the item to get")],
    q: Annotated[Union[str, None], Query(alias="item-query")] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    return results

参数列表

参数 含义 类型
... 和Query具有相同参数 ...
ge 大于等于 int float
gt 大于 int float
le 小于等于 int float
le 小于等于 int float
title api文档的标题 string

其他参数

都具有Query的参数，max_length、min_length等

Cookie参数 

from fastapi import Cookie
@app.get("/items/")
async def read_items(ads_id: Annotated[Union[str, None], Cookie()] = None):
    return {"ads_id": ads_id}

Header 参数 

from fastapi import Header
@app.get("/items/")
async def read_items(user_agent: Annotated[Union[str, None], Header()] = None,items_id: Annotated[Union[int, None], Header(ge=1)] = None):
    return {"User-Agent": user_agent, "items_id": items_id}

表单数据

接收的不是 JSON，而是表单字段时，要使用 Form。

安装

pip install python-multipart

HTML 

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
</head>
<body>
<form method="post" action="http://127.0.0.1:8000/login">
    <span>账号：</span><input type="text" name="username">
    <br>
    <span>密码：</span><input type="password" name="password">
    <br>
    <input type="submit" value="登录">
</form>
</body>
</html>

FastAPI 

from fastapi import FastAPI, Form
import uvicorn
app = FastAPI()
@app.post("/login/")
async def login(username: str = Form(), password: str = Form()):
    return {"username": username}
if __name__ == '__main__':
    uvicorn.run(app='main:app', reload=True)

文件上传 

from fastapi import FastAPI, UploadFile
from fastapi.responses import HTMLResponse
@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile):
    print(file.file.read().decode())
    return {"filenames": file.filename, "type": str(type(file.file))}
@app.get("/")
async def main():
    content = """<body>
<form action="/uploadfile/" enctype="multipart/form-data" method="post">
<input name="file" type="file" multiple>
<input type="submit">
</form>
</body>"""
    return HTMLResponse(content=content)

UploadFile属性

属性名 含义 返回
filename 文件名 上传的文件名
content_type 内容类型 MIME 类型
file 文件 SpooledTemporaryFile具有read，write方法

UploadFile async方法

方法名 含义
write(data) 把 data 写入文件
read(size) 按指定数量的字节读取文件内容
seek(offset) 移动至文件 offset （int）字节处的位置
close() 关闭文件

依赖项

依赖项使用场景

  • 共享业务逻辑（复用相同的代码逻辑）
  • 共享数据库连接
  • 实现安全、验证、角色权限
  • 等……

创建依赖项 

from typing import Union

from fastapi import Depends, FastAPI

app = FastAPI()

# read_items和read_users方法依赖common_parameters
# 白话就是read_items和read_users都需要q，skip，limit查询参数
async def common_parameters(
    q: Union[str, None] = None, skip: int = 0, limit: int = 100
):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/items/")
async def read_items(commons: dict = Depends(common_parameters)):
    return commons


@app.get("/users/")
async def read_users(commons: dict = Depends(common_parameters)):
    return commons

类作为依赖项 

from typing import Union

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit

# read_itemsx接收一个commons参数，类型是CommonQueryParams
# CommonQueryParams接收三个参数，这三个参数是调用api的时候传
@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends(CommonQueryParams)):
    response = {}
    if commons.q:
        response.update({"q": commons.q})
    items = fake_items_db[commons.skip : commons.skip + commons.limit]
    response.update({"items": items})
    return response

还可以简写 

@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends()): # 这里的Depends没有传参，FastAPI会自动使用CommonQueryParams
    response = {}
    if commons.q:
        response.update({"q": commons.q})
    items = fake_items_db[commons.skip : commons.skip + commons.limit]
    response.update({"items": items})
    return response

子依赖项 

from typing import Union

from fastapi import Cookie, Depends, FastAPI

app = FastAPI()


def query_extractor(q: Union[str, None] = None):
    return q


def query_or_cookie_extractor(
    q: str = Depends(query_extractor),
    last_query: Union[str, None] = Cookie(default=None),
):
    if not q:
        return last_query
    return q

# read_query函数依赖query_or_cookie_extractor函数
# query_or_cookie_extractor函数又依赖query_extractor函数
# 就是说依赖项可以依赖其他依赖项，只要你不晕，可以无数次套娃
@app.get("/items/")
async def read_query(query_or_default: str = Depends(query_or_cookie_extractor)):
    return {"q_or_cookie": query_or_default}

不使用缓存 

# 使用use_cache = False参数不使用缓存数据
# 不使用use_cache = False,value和value1是一样的
def result_value():
    value = randint(1, 99)
    return value

def get_value(value: int = Depends(result_value, use_cache=False), value1: int = Depends(result_value, use_cache=False)):
    return value, value1

@app.get('/value/')
async def needy_dependency(value: tuple = Depends(get_value)):
    return {"value": value}

全局依赖项 

from fastapi import Depends, FastAPI, Header, HTTPException


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key

# 全局依赖项很有用，后面的安全性就可以使用全局依赖项
app = FastAPI(dependencies=[Depends(verify_token), Depends(verify_key)])


@app.get("/items/")
async def read_items():
    return [{"item": "Portal Gun"}, {"item": "Plumbus"}]


@app.get("/users/")
async def read_users():
    return [{"username": "Rick"}, {"username": "Morty"}]

安全性

待更新

参考