那些遇到过的问题

FastAPI - Pydantic - 值错误引发内部服务器错误

Raj*_*eer 17 python python-3.x pydantic fastapi

我正在将 FastAPI 与 Pydantic 结合使用。

我的问题 - 我需要使用 Pydantic 引发 ValueError

from fastapi import FastAPI
from pydantic import BaseModel, validator
from fastapi import Depends, HTTPException

app = FastAPI()

class RankInput(BaseModel):

    rank: int

    @validator('rank')
    def check_if_value_in_range(cls, v):
        """
        check if input rank is within range
        """
        if not 0 < v < 1000001:

            raise ValueError("Rank Value Must be within range (0,1000000)")
            #raise HTTPException(status_code=400, detail="Rank Value Error") - this works But I am looking for a solution using ValueError
        return v

def get_info_by_rank(rank):
    return rank

@app.get('/rank/{rank}')
async def get_rank(value: RankInput = Depends()):
    result = get_info_by_rank(value.rank)
    return result
Run Code Online (Sandbox Code Playgroud)

这段代码Internal Server Error在引发 ValueError 时给出

INFO:     127.0.0.1:59427 - "GET /info/?rank=-1 HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/uvicorn/protocols/http/h11_impl.py", line 396, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
    return await self.app(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/applications.py", line 199, in __call__
    await super().__call__(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/applications.py", line 111, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/middleware/errors.py", line 181, in __call__
    raise exc from None
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/exceptions.py", line 82, in __call__
    raise exc from None
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/exceptions.py", line 71, in __call__
    await self.app(scope, receive, sender)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 566, in __call__
    await route.handle(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 227, in handle
    await self.app(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 41, in app
    response = await func(request)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/routing.py", line 195, in app
    dependency_overrides_provider=dependency_overrides_provider,
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/dependencies/utils.py", line 550, in solve_dependencies
    solved = await run_in_threadpool(call, **sub_values)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/concurrency.py", line 34, in run_in_threadpool
    return await loop.run_in_executor(None, func, *args)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "pydantic/main.py", line 400, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for GetInput
rank
  ValueError() takes no keyword arguments (type=type_error)
ERROR:uvicorn.error:Exception in ASGI application
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/uvicorn/protocols/http/h11_impl.py", line 396, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
    return await self.app(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/applications.py", line 199, in __call__
    await super().__call__(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/applications.py", line 111, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/middleware/errors.py", line 181, in __call__
    raise exc from None
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/exceptions.py", line 82, in __call__
    raise exc from None
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/exceptions.py", line 71, in __call__
    await self.app(scope, receive, sender)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 566, in __call__
    await route.handle(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 227, in handle
    await self.app(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/routing.py", line 41, in app
    response = await func(request)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/routing.py", line 195, in app
    dependency_overrides_provider=dependency_overrides_provider,
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/fastapi/dependencies/utils.py", line 550, in solve_dependencies
    solved = await run_in_threadpool(call, **sub_values)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/starlette/concurrency.py", line 34, in run_in_threadpool
    return await loop.run_in_executor(None, func, *args)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "pydantic/main.py", line 400, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for GetInput
rank
  ValueError() takes no keyword arguments (type=type_error)
Run Code Online (Sandbox Code Playgroud)

我还检查了https://github.com/tiangolo/fastapi/issues/2180。

但我无法找到解决方案。

我需要做的是ValueError使用自定义状态代码来提高。

注意 - 我知道我可以通过提高 来完成工作HTTPException。

但我正在寻找使用的解决方案ValueError

你能告诉我哪里出错了吗？

还在 Github 上发布了此问题 - https://github.com/tiangolo/fastapi/issues/3761

Ben*_*Ben 14

如果您没有引发，HTTPException那么通常任何其他未捕获的异常都会生成 500 响应（Internal Server Error）。如果您的目的是在引发特定异常时响应一些其他自定义错误消息和 HTTP 状态 - 例如ValueError- 那么您可以使用向您的应用程序添加全局异常处理程序：

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse


@app.exception_handler(ValueError)
async def value_error_exception_handler(request: Request, exc: ValueError):
    return JSONResponse(
        status_code=400,
        content={"message": str(exc)},
    )
Run Code Online (Sandbox Code Playgroud)

这将给出 400 响应（或者您可以将状态代码更改为您喜欢的任何内容），如下所示：

{
    "message": "Value Must be within range (0,1000000)"
}
Run Code Online (Sandbox Code Playgroud)

  • 好的，谢谢，您的模型正在用作依赖项。DI 系统将处理模型验证器引发的 HTTPException，但任何其他情况都会根据设计导致 500。[参见此处](https://fastapi.tiangolo.com/tutorial/handling-errors/#requestvalidationerror-vs-validationerror) 如果您希望您的应用程序以自定义方式从模型响应而不使用 HTTPException，我的唯一方法我知道的是引发自定义异常并向返回自定义响应的应用程序添加自定义异常处理程序。但您无法直接从模型返回响应。 (2认同)

Pau*_*l P 10

请注意，pydantic期望验证器提出一个ValueError, TypeError, 或AssertionError（参见文档），它将pydantic转换为ValidationError.

此外，根据FastAPI 的文档：

当请求包含无效数据时，FastAPI 会在内部引发RequestValidationError.

和

RequestValidationError是 Pydantic 的子类ValidationError。

这样做的结果是，在 的 模型验证Validation期间引发的标准错误pydantic将被转换为422 Unprocessable Entity，并且响应正文将包含有关验证失败原因的详细信息。

（附带说明：pydantic带有约束类型，允许约束基本数据类型，而无需编写显式验证器。）

如果上述方法不令人满意并且您想更改行为，我将采用以下方法（有关处理的详细信息，请参阅此处ValidationError）：

from fastapi import Depends, FastAPI, Request, status
from fastapi.exceptions import RequestValidationError
from fastapi.exception_handlers import request_validation_exception_handler
from fastapi.responses import JSONResponse
from pydantic import BaseModel, conint

class RankInput(BaseModel):
    # Constrained integer, must be greater than or equal to 0
    # and less than or equal to 1 million.
    rank: conint(ge=0, le=1_000_000)

async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):

    validation_errors = exc.errors()
    for err in validation_errors:
        # You could check for other things here as well, e.g. the error type.
        if "rank" in err["loc"]:
            return JSONResponse(
                status_code=status.HTTP_400_BAD_REQUEST,
                content={"message": "Rank must be in range [0, 1000000]."}
            )

    # Default response in every other case.
    return await request_validation_exception_handler(request, exc)

def get_info_by_rank(rank):
    return rank


app = FastAPI(
    exception_handlers={RequestValidationError: rank_out_of_bound_handler},
)

@app.get('/rank/{rank}')
async def get_rank(value: RankInput = Depends()):
    result = get_info_by_rank(value.rank)
    return result
Run Code Online (Sandbox Code Playgroud)

现在对端点的调用给出：

$ curl -i "http://127.0.0.1:8000/rank/1"
HTTP/1.1 200 OK
date: Sat, 28 Aug 2021 20:47:58 GMT
server: uvicorn
content-length: 1
content-type: application/json

1
Run Code Online (Sandbox Code Playgroud) 
$  curl -i "http://127.0.0.1:8000/rank/-1"
HTTP/1.1 400 Bad Request
date: Sat, 28 Aug 2021 20:48:24 GMT
server: uvicorn
content-length: 49
content-type: application/json

{"message":"Rank must be in range [0, 1000000]."}
Run Code Online (Sandbox Code Playgroud) 
$ curl -i "http://127.0.0.1:8000/rank/1000001"
HTTP/1.1 400 Bad Request
date: Sat, 28 Aug 2021 20:48:51 GMT
server: uvicorn
content-length: 49
content-type: application/json

{"message":"Rank must be in range [0, 1000000]."}
Run Code Online (Sandbox Code Playgroud)

如果您要添加使用相同模型的不同端点，异常处理程序也会自动处理此问题，例如：

@app.get('/other-rank/{rank}')
async def get_other_rank(value: RankInput = Depends()):
    result = get_info_by_rank(value.rank)
    return result
Run Code Online (Sandbox Code Playgroud) 
$ curl -i "http://127.0.0.1:8000/other-rank/-1"
HTTP/1.1 400 Bad Request
date: Sat, 28 Aug 2021 20:54:16 GMT
server: uvicorn
content-length: 49
content-type: application/json

{"message":"Rank must be in range [0, 1000000]."}
Run Code Online (Sandbox Code Playgroud)

如果这不是您想要的，您能解释一下为什么您想提出 吗ValueError？

归档时间：

查看次数：

29026 次

最近记录：

2 年，8 月 前
相关归档
如何在pandas数据帧中执行字符串的左,右和中间 47
Python ValueError错误消息 42
在Python 3.2中使用"Counter" 19
在python 3中用urllib打开一个url 18
了解zip功能 14
如何使logging.logger表现得像print 7
如何为pip设置默认的python版本？ 6
Celery vs RQ 基准测试 6
如何在 FastAPI 中将 RedirectResponse 从 POST 发送到 GET 路由？ 5
FastAPI 中的部分更新 4
难疑归档
"px","dip","dp"和"sp"之间有什么区别？ 5676
是否可以将CSS应用于角色的一半？ 2717
一次捕获多个异常？ 2015
NPM vs. Bower vs. Browserify vs. Gulp vs. Grunt vs. Webpack 1811
如何修复java.lang.UnsupportedClassVersionError:不支持的major.minor版本 1532
在视图控制器之间传递数据 1340
为什么在允许某些Unicode字符的注释中执行Java代码？ 1326
如何从GET参数中获取值？ 1255
如何使用AngularJS在浏览器控制台中访问$ scope变量？ 1220
Vim最有效的捷径是什么？ 1127