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Handlers

BaseHandler

BaseHandler is only an abstract base class. You can't use it directly.

Let's Take a look at some of its functions:

BaseHandler
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class BaseHandler(abc.ABC):

    def preprocess(self, data: object, parameters: object = None):
        return data # (1)

    def postprocess(self, data: object, parameters: object = None):
        return data # (2)

    def predict(self, data: object):
        if not getattr(self, "model", None):
            raise Exception("Model is not loaded.")
        predict_func = ( # (3)
            getattr(self.model, self.entrypoint)
            if self.entrypoint
            else self.model
        )
        return predict_func(data)

    @abc.abstractmethod
    def load_model(self):
        return NotImplemented # (4)

  1. The default codes do nothing. You can override this function to provide your own pre-processing codes.

  2. The default codes do nothing. You can override this function to provide your own post-processing codes.

  3. Get predict function from entrypoint name and the model object. Model can be accessed by self.model, the entrypoint registered can be accessed by self.entrypoint.

  4. You need to implement this function. Model path can be accessed by self.model_path

PickleHandler

The default handler is PickleHandler.

PickleHandler
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class PickleHandler(BaseHandler):
    """Pickle Handler for Models Saved through Pickle"""

    def load_model(self):
        if not getattr(self, "model_path", None):
            raise Exception("Model path not provided.")
        with open(self.model_path, "rb") as f:
            return pickle.load(f)