<img src="/img/tutorial/custom-response/image01.png">

## Available responses

Here are some of the available responses.

Keep in mind that you can use `Response` to return anything else, or even create a custom sub-class.

!!! note "Technical Details"
    You could also use `from starlette.responses import HTMLResponse`.

        )
        self.exception_handlers: Dict[
            Any, Callable[[Request, Any], Union[Response, Awaitable[Response]]]
        ] = {} if exception_handlers is None else dict(exception_handlers)
        self.exception_handlers.setdefault(HTTPException, http_exception_handler)
        self.exception_handlers.setdefault(
            RequestValidationError, request_validation_exception_handler

        dependant.request_param_name = param_name
        return True
    elif lenient_issubclass(type_annotation, WebSocket):
        dependant.websocket_param_name = param_name
        return True
    elif lenient_issubclass(type_annotation, HTTPConnection):
        dependant.http_connection_param_name = param_name
        return True
    elif lenient_issubclass(type_annotation, Response):

        if field_info.description:
            parameter["description"] = field_info.description
        if field_info.openapi_examples:
            parameter["examples"] = jsonable_encoder(field_info.openapi_examples)
        elif field_info.example != Undefined:
            parameter["example"] = jsonable_encoder(field_info.example)
        if field_info.deprecated:
            parameter["deprecated"] = True
        parameters.append(parameter)

class RoleEnum(Enum):
    admin = "admin"
    normal = "normal"


class ModelWithConfig(BaseModel):
    role: Optional[RoleEnum] = None

    if PYDANTIC_V2:
        model_config = {"use_enum_values": True}
    else:

        class Config:
            use_enum_values = True


class ModelWithAlias(BaseModel):
    foo: str = Field(alias="Foo")


class ModelWithDefault(BaseModel):
    foo: str = ...  # type: ignore

        if not api_key:
            if self.auto_error:
                raise HTTPException(
                    status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                )
            else:
                return None
        return api_key


class APIKeyHeader(APIKeyBase):
    """
    API key authentication using a header.

    return user


def create_access_token(data: dict, expires_delta: timedelta | None = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

        @app.post("/items/")
        async def read_items(
            q: Annotated[str | None, Form(regex="^fixedquery$")] = None,
        ):
            if q:
                return f"Hello {q}"
            else:
                return "Hello World"

    client = TestClient(app)
    return client


@needs_py310
def test_no_query():
    client = get_client()
    response = client.post("/items/")

# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

So, a Python class is also a **callable**.

Then, in **FastAPI**, you could use a Python class as a dependency.

What FastAPI actually checks is that it is a "callable" (function, class or anything else) and the parameters defined.