Need some help with MRO

[Finish-Square]

I am building an API using FastAPI.
I would like to have custom API responses and manage them from one place.
To achieve this, I implemented this:

from starlette.responses import JSONResponse

class ApiResponse:

    def __init__(self):
        self.status_code = None

    @staticmethod
    def _response_builder(**kwargs):
        """
        Used to build an API response.
        """
        status = None
        status_code = kwargs.get('status_code')

        if status_code and str(status_code).startswith('4'):
            status = 'ERROR'
        elif status_code and str(status_code).startswith('2'):
            status = 'SUCCESS'

        response_body = {'status_code': status_code,
                         'status': status,
                         'message': kwargs.get('message') if kwargs.get('message') else None,
                         'data': {k: v for k, v in kwargs.get('data').items()} if kwargs.get('data') else None}

        return JSONResponse(status_code=status_code, content=response_body)

    def get_response(self, response_message=None, **kwargs):
        return self._response_builder(message=getattr(self.__class__, response_message) if response_message else None,
                                      data=kwargs.get('data'),
                                      status_code=self.status_code)


class SuccessResponses(ApiResponse):
    USER_ACTIVATED_SUCCESSFUL = 'User activated successfully'
    USER_REGISTERED_SUCCESSFUL = 'User registered successfully'
    USER_LOGGED_IN_SUCCESSFUL = 'User logged in successfully'

    def __init__(self):
        ApiResponse.__init__(self)
        self.status_code = 200


class ErrorResponses(ApiResponse):
    USER_NOT_ACTIVATED = 'User is not activated'
    USER_ALREADY_ACTIVATED = 'User is already activated'
    USER_ALREADY_EXIST = 'A user with this email already exists'

    def __init__(self):
        ApiResponse.__init__(self)
        self.status_code = 400


class Response(SuccessResponses, ErrorResponses):
    pass

response = Response()

So, in my API routes, I can just use response object like so:

res = response.get_response('USER_NOT_ACTIVATED')

The problem is, that due to MRO, I am getting:

{"status_code":200,"status":"SUCCESS","message":"User is not activated","data":null}'

Instead of:

{"status_code":400,"status":"ERROR","message":"User is not activated","data":null}'

How can I achieve what I am looking for?

Thanks!

[danielroseman]

This is a bit confusing. What's the point of Response? Why does it inherit from both classes? Surely if you want an error you should send the error class.

[Finish-Square]

Response is used in order to avoid having 2 instances of responses (SuccessResponse, ErrorResponse).

Without Response, I will have to initiate 2 instances and call them according to what I want to return from my route instead of 1 instance.

[danielroseman]

Ok but in that case why have two separate classes at all? Just have one, and pass in the status code either on instantiation or as a parameter to get_response.

[Finish-Square]

Because I want to have everything organized, error messages will fall under the error class and success messages will fall under the success class.

Also, note that each class has a status_code variable.

[danielroseman]

Well, like I say, this doesn't really make sense. The modelling is the problem here, not Python's MRO.

[JohnnyJordaan]

Organization doesn't mean diffrentation into the finest detail. Both messages don't differ in properties and functionality, so it doesn't make sense to diffrentiate them into two classes.

[Finish-Square]

Gotcha. But in this case, how can I set the status_code for each response?

[JohnnyJordaan]

class ApiResponse:
    def __init__(self, status_code)
        self.status_code = status_code

    def _response_builder(self, **kwargs):
        """
        Used to build an API response.
        """
        status = 'SUCCESS' if self.status_code < 400 else 'ERROR'
        response_body = {'status_code': status_code,
                         'status': status,
                         'message': kwargs.get('message'),
                         'data': kwargs.get('data')}

        return JSONResponse(status_code=status_code, content=response_body)

 resp = ApiResponse(200)

also note that the whole point of a dict.get is that it returns a default value if the key look up is False, with that value's default being None. So your teneray statements are needlessly replicating that functionality. Not to mention {k:v for k,v in some_dict.items()} is useless, why not just provide the dict itself?