Python Fastapi实现统一处理各种异常

from fastapi import FastAPI, Request, status
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse

app = FastAPI()

@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(
        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
        content={
            "code": 422,
            "message": "参数校验失败",
            "errors": exc.errors()
        },
    )

# 示例路由
@app.get("/items/{item_id}")
async def read_item(item_id: int, q: str):
    return {"item_id": item_id, "q": q}

@app.exception_handler(RequestValidationError)
async def custom_validation_handler(request: Request, exc: RequestValidationError):
    simplified_errors = []
    for error in exc.errors():
        # 提取关键信息
        simplified_errors.append({
            "field": "->".join(str(loc) for loc in error["loc"]),  # 错误字段路径
            "msg": error["msg"],
            "type": error["type"]
        })
    
    return JSONResponse(
        status_code=422,
        content={
            "error": "ValidationError",
            "detail": simplified_errors
        }
    )

from pydantic import BaseModel, Field

class Item(BaseModel):
    name: str = Field(..., min_length=3)
    price: float = Field(gt=0)

@app.post("/items/")
async def create_item(item: Item):
    return item

# 测试无效请求
# curl -X POST 'http://localhost:8000/items/' \
# -H 'Content-Type: application/json' \
# -d '{"name": "AB", "price": -1}'

from fastapi import HTTPException

@app.exception_handler(HTTPException)
async def http_exception_handler(request: Request, exc: HTTPException):
    return JSONResponse(
        status_code=exc.status_code,
        content={"error": exc.detail}
    )

{
  "loc": ["body", "price"],
  "msg": "ensure this value is greater than 0",
  "type": "value_error.number.not_gt"
}

import os

@app.exception_handler(RequestValidationError)
async def handler(...):
    if os.getenv("ENV") == "prod":
        return JSONResponse(status_code=422, content={"error": "Invalid params"})
    else:
        # 返回完整错误

{
  "code": 422,
  "message": "参数校验失败",
  "errors": [
    {
      "field": "body->name",
      "msg": "ensure this value has at least 3 characters",
      "type": "value_error.any_str.min_length"
    },
    {
      "field": "body->price",
      "msg": "ensure this value is greater than 0",
      "type": "value_error.number.not_gt"
    }
  ]
}