class ModelA(BaseModel):
    name: str
    description: Optional[str] = None
    model_b: ModelB

    @validator("name")
    def lower_username(cls, name: str, values):
        if not name.endswith("A"):
            raise ValueError("name must end in A")
        return name


async def get_model_c() -> ModelC:
    return ModelC(username="test-user", password="test-password")


@app.get("/model/{name}", response_model=ModelA)

Und Sie möchten diese Exception global mit FastAPI handhaben.

Sie könnten einen benutzerdefinierten Exceptionhandler mittels `@app.exception_handler()` hinzufügen:

```Python hl_lines="5-7  13-18  24"
{!../../docs_src/handling_errors/tutorial003.py!}
```

Wenn Sie nun `/unicorns/yolo` anfragen, `raise`d die *Pfadoperation* eine `UnicornException`.

            except yaml.YAMLError as ex:
                print(ex)

        return res
    except KeyError as ke:
        if 'kind' in str(ke) or 'data' in str(ke):
            return res

        raise


def normalize_ports(res):
    try:
        spec = res["spec"]
        if spec is None:
            return res
        ports = sorted(spec['ports'], key=lambda x: x["port"])
        spec['ports'] = ports

    async def __call__(self, request: Request) -> Optional[str]:
        api_key = request.query_params.get(self.model.name)
        if not api_key:
            if self.auto_error:
                raise HTTPException(
                    status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                )
            else:
                return None
        return api_key

        content={"message": f"Oops! {exc.name} did something. There goes a rainbow..."},
    )


@app.get("/unicorns/{name}")
async def read_unicorn(name: str):
    if name == "yolo":
        raise UnicornException(name=name)

        )
        logging.error(response.text)
        raise RuntimeError(response.text)
    data = response.json()
    if "errors" in data:
        logging.error(f"Errors in response, after: {after}, category_id: {category_id}")
        logging.error(response.text)
        raise RuntimeError(response.text)
    return cast(Dict[str, Any], data)

    except Exception as e:
        ok = bool(
            await anyio.to_thread.run_sync(
                cm.__exit__, type(e), e, None, limiter=exit_limiter
            )
        )
        if not ok:
            raise e
    else:
        await anyio.to_thread.run_sync(
            cm.__exit__, None, None, None, limiter=exit_limiter

                                          preload_content=True,
                                          )
            if response.status != 200:
                message = "Credential refresh failed, response: %s"
                raise CredentialRetrievalError(
                    provider=method,
                    error_msg=message % response.status,
                )

            creds = json.loads(response.data)

            query = {}

    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username

        if not isinstance(v, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(v)}")
        return v

    @classmethod
    def _validate(cls, __input_value: Any, _: Any) -> "UploadFile":
        if not isinstance(__input_value, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(__input_value)}")