User Exceptions raised in predict function of a wrapper class needs to be handled via flask exception handler

[klalit]

In https://github.com/SeldonIO/seldon-core/blob/master/python/seldon_core/wrapper.py the handler is present for SeldonMicroserviceException but not for user exception. I'm thinking to have a handler created for "Exception" and the function to handle it can be defined in the user model. Please let me know the thoughts or a better way to accomplish the requirement

[klalit]

I'm planning to use flask Blueprint so that application developers can integrate in a flexible and cleaner way. Here is the example

Model wrapper

class UserObject(SeldonComponent):

 ** The variable defined for the wrapper.py to consider dusring flask app initialization **
    model_error_handler = flask.Blueprint('error_handlers', __name__)

 ** Register the exception handler **
    @model_error_handler.app_errorhandler(UserCustomException)
    def handleCustomError(error):
        response = jsonify(error.to_dict())
        response.status_code = error.status_code
        return response

    def __init__(self, metrics_ok=True, ret_nparray=False, ret_meta=False):
        pass

    def predict(self, X, features_names, **kwargs):
        raise UserCustomException('Test-Error-Msg',1402,402)
        return X

User exception

class UserCustomException(Exception):
    status_code = 404

    def __init__(self, message, application_error_code,http_status_code):
        Exception.__init__(self)
        self.message = message
        if http_status_code is not None:
            self.status_code = http_status_code
        self.application_error_code = application_error_code

    def to_dict(self):
        rv = {"status": {"status": self.status_code, "message": self.message,
                         "app_code": self.application_error_code}}
        return rv