process.py

def run():
    with beam.Pipeline(options=options) as p:
        raw_values = (
            p 
            | "ReadTable" >> beam.io.Read(source) 
            | "cleanup" >> beam.ParDo(ElementCleanup())
            | "writeTable" >> beam.io.Write(target)
            )
        # pipeline
        # parDo for all values in PCollection: process
        # each element: define a target datatype and a set of cleanup functions for each


class ElementCleanup(beam.DoFn):
    """
    tasker uses the %VAR_NAME syntax to construct JSON. Sometimes, values aren't replaced. In these cases, the string starts with a "%". If this is the case, simply replace it with a None
    """
    
    def __init__(self):
        self.transforms = self.make_transform_map()
    def make_transform_map(self):
        return {
            "battery_status":    [self.trim, self.percent_cleaner, self.to_int],
            "bluetooth_status":  [self.trim, self.percent_cleaner, ],
            "cell_id":           [self.trim, self.percent_cleaner, ],
            "cell_strength":     [self.trim, self.percent_cleaner, self.to_int],
            "gps_status":        [self.trim, self.percent_cleaner, ],
            "last_app":          [self.trim, self.percent_cleaner, ],
            "location_gps":      [self.trim, self.percent_cleaner, ], #keeping encoding as "LAT,LON" as data studio likes this
            "location_net":      [self.trim, self.percent_cleaner, ], #keeping encoding as "LAT,LON" as data studio likes this
            "location_accuracy": [self.trim, self.percent_cleaner, self.to_float],
            "altitude":          [self.trim, self.percent_cleaner, self.to_float],
            "speed":             [self.trim, self.percent_cleaner, self.to_float],
            "location_seconds":  [self.trim, self.percent_cleaner, ],
            "timestamp":         [self.trim, self.percent_cleaner, self.to_int],
        }

    def process(self, row):
        #process receives the object and (must) return an iterable (in case of breaking objects up into several)
        return [self.handle_row(row, self.transforms)]


    def handle_row(self, row, transforms):
        fixed = {}
        for key in row.keys():
            val = row[key]
            for func in transforms[key]:
                val = func(val)
            fixed[key] = val
        return fixed

    def percent_cleaner(self, value: str):
        if isinstance(value, str) and value.startswith("%"):
            return None
        else:
            return value

    def trim(self, val:str):
        return val.strip()

    def to_int(self, val: str):
        return (int(val) if val != None else None)

    def to_float(self, val: str):
        return (float(val) if val != None else None)


if __name__ == "__main__":
    run()