FastAPI（高性能Web框架）

from pydantic import BaseModel, Field
from typing import Optional

class UserCreate(BaseModel):
    username: str = Field(..., min_length=2, max_length=50)  # 必填，2-50 字符
    email: str                                                # 必填
    age: Optional[int] = Field(None, ge=0, le=150)           # 可选，0-150 之间

# 传入合法数据 → 自动通过验证
user = UserCreate(username="alice", email="alice@test", age=25)
print(user.model_dump())
# {'username': 'alice', 'email': 'alice@test', 'age': 25}

# 传入非法数据 → 自动抛出详细错误信息
# UserCreate(username="a", email="bad", age=200)  → ValidationError

from fastapi import FastAPI

app = FastAPI()

# 异步路由：适合有 I/O 等待的场景
@app.get("/async-hello")
async def async_hello():
    return {"message": "异步响应"}

# 同步路由：FastAPI 自动放到线程池执行，不阻塞事件循环
@app.get("/sync-hello")
def sync_hello():
    return {"message": "同步响应"}

from fastapi import Depends, HTTPException

# 定义一个依赖：模拟认证
async def get_current_user(token: str = ""):
    if token != "secret-token":
        raise HTTPException(status_code=401, detail="未授权")
    return {"user_id": 1, "name": "alice"}

# 路由函数通过 Depends 自动获取当前用户
@app.get("/me")
async def read_me(user: dict = Depends(get_current_user)):
    return user

pip install fastapi uvicorn

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel, Field
from typing import Optional

app = FastAPI(title="待办事项 API")

# 数据模型
class Todo(BaseModel):
    id: int
    title: str = Field(..., min_length=1, max_length=100)
    done: bool = False

# 内存存储
todos: dict[int, Todo] = {}

@app.get("/")
async def root():
    return {"message": "待办事项 API 运行中"}

@app.post("/todos/", response_model=Todo, status_code=201)
async def create_todo(todo: Todo):
    """创建一条待办事项"""
    if todo.id in todos:
        raise HTTPException(status_code=400, detail="ID 已存在")
    todos[todo.id] = todo
    return todo

@app.get("/todos/", response_model=list[Todo])
async def list_todos():
    """获取所有待办事项"""
    return list(todos.values())

@app.get("/todos/{todo_id}", response_model=Todo)
async def get_todo(todo_id: int):
    """根据 ID 获取待办事项"""
    if todo_id not in todos:
        raise HTTPException(status_code=404, detail="不存在")
    return todos[todo_id]

@app.delete("/todos/{todo_id}", status_code=204)
async def delete_todo(todo_id: int):
    """删除待办事项"""
    if todo_id not in todos:
        raise HTTPException(status_code=404, detail="不存在")
    del todos[todo_id]

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000)

INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Application startup complete.

# 测试创建
$ curl -X POST http://localhost:8000/todos/ -H "Content-Type: application/json" -d '{"id":1,"title":"学FastAPI"}'
{"id":1,"title":"学FastAPI","done":false}

# 测试列表
$ curl http://localhost:8000/todos/
[{"id":1,"title":"学FastAPI","done":false}]

# 浏览器打开 http://localhost:8000/docs 可看到自动生成的 Swagger 交互文档