I have used mlflow and got my model served through REST API. It work fine when all model features are provided. But my use case is that only a single feature (the primary key) will be provided by the consumer application, and my code has to lookup the other features from a database based on that key and then use the model.predict to return the prediction. I tried researching but understood that the REST endpoints will simply invoke the model.predict function. How can I make it invoke a data massaging function before predicting?