名称: fastapi开发 描述: 使用FastAPI构建异步API，包括端点、依赖注入、验证和测试。适用于创建REST API、Web后端或微服务。
FastAPI开发
快速开始
创建一个基础的FastAPI应用：
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
async def read_root():
return {"Hello": "World"}
@app.get("/items/{item_id}")
async def read_item(item_id: int, q: str | None = None):
return {"item_id": item_id, "q": q}
运行命令：
uv run uvicorn main:app --reload
常用模式
使用Pydantic模型进行验证
from pydantic import BaseModel
from typing import Optional
class Item(BaseModel):
name: str
description: Optional[str] = None
price: float
tax: Optional[float] = None
@app.post("/items/")
async def create_item(item: Item):
return item
依赖注入
from typing import Annotated
from fastapi import Depends
async def common_parameters(
q: str | None = None,
skip: int = 0,
limit: int = 100
):
return {"q": q, "skip": skip, "limit": limit}
CommonsDep = Annotated[dict, Depends(common_parameters)]
@app.get("/items/")
async def read_items(commons: CommonsDep):
return commons
带清理功能的数据库依赖
async def get_db():
db = connect_to_database()
try:
yield db
finally:
db.close()
@app.get("/query/")
async def query_data(db: Annotated[dict, Depends(get_db)]):
return {"data": "query results"}
错误处理
from fastapi import HTTPException
@app.get("/items/{item_id}")
async def read_item(item_id: int):
if item_id < 1:
raise HTTPException(status_code=404, detail="Item not found")
return {"item_id": item_id}
路径和查询参数验证
from typing import Annotated
from fastapi import Path, Query
@app.get("/items/{item_id}")
async def read_item(
item_id: Annotated[int, Path(gt=0, le=1000)],
q: Annotated[str, Query(max_length=50)] = None
):
return {"item_id": item_id, "q": q}
响应模型
from pydantic import BaseModel
class ItemPublic(BaseModel):
id: int
name: str
price: float
@app.get("/items/{item_id}", response_model=ItemPublic)
async def read_item(item_id: int):
return ItemPublic(id=item_id, name="Laptop", price=999.99)
使用TestClient进行测试
from fastapi.testclient import TestClient
client = TestClient(app)
def test_read_root():
response = client.get("/")
assert response.status_code == 200
assert response.json() == {"Hello": "World"}
def test_read_item():
response = client.get("/items/42?q=test")
assert response.status_code == 200
assert response.json() == {"item_id": 42, "q": "test"}
依赖要求
uv add fastapi uvicorn
uv add "fastapi[all]" # 包含所有可选依赖
核心概念
- 异步/等待：对I/O操作使用
async def - 自动验证：使用Pydantic进行请求/响应验证
- 依赖注入：通过
Depends在端点间共享逻辑 - 类型提示：完整的编辑器支持和验证
- 交互式文档：在
/docs自动生成Swagger/OpenAPI文档 - 后台任务：使用
BackgroundTasks在响应后运行任务