learning/katas/python/Streaming/Timestamps/Add Timestamps/task.py

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# beam-playground:
#   name: WindowingParDo
#   description: Task from katas to assign each element a timestamp based on the `Event.timestamp`.
#   multifile: false
#   context_line: 52
#   categories:
#     - Streaming
#   complexity: MEDIUM
#   tags:
#     - timestamp
#     - event

import datetime
import pytz

import apache_beam as beam
from apache_beam.transforms import window


class Event:
    def __init__(self, id, event, timestamp):
        self.id = id
        self.event = event
        self.timestamp = timestamp

    def __str__(self) -> str:
        return f'Event({self.id}, {self.event}, {self.timestamp})'


class AddTimestampDoFn(beam.DoFn):
    def process(self, element, **kwargs):
        unix_timestamp = element.timestamp.timestamp()
        yield window.TimestampedValue(element, unix_timestamp)


with beam.Pipeline() as p:
  (p | beam.Create([
          Event('1', 'book-order', datetime.datetime(2020, 3, 4, 0, 0, 0, 0, tzinfo=pytz.UTC)),
          Event('2', 'pencil-order', datetime.datetime(2020, 3, 5, 0, 0, 0, 0, tzinfo=pytz.UTC)),
          Event('3', 'paper-order', datetime.datetime(2020, 3, 6, 0, 0, 0, 0, tzinfo=pytz.UTC)),
          Event('4', 'pencil-order', datetime.datetime(2020, 3, 7, 0, 0, 0, 0, tzinfo=pytz.UTC)),
          Event('5', 'book-order', datetime.datetime(2020, 3, 8, 0, 0, 0, 0, tzinfo=pytz.UTC)),
       ])
     | beam.ParDo(AddTimestampDoFn())
     | beam.LogElements(with_timestamp=True))