learning/tour-of-beam/learning-content/windowing/adding-timestamp/python-example/task.py

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# beam-playground:
#   name: adding-timestamp
#   description: Adding-timestamp example.
#   multifile: false
#   context_line: 68
#   categories:
#     - Quickstart
#   complexity: ADVANCED
#   tags:
#     - hellobeam


import datetime
import pytz

import apache_beam as beam
from apache_beam import window


class Output(beam.PTransform):
    class _OutputFn(beam.DoFn):
        def __init__(self, prefix=''):
            super().__init__()
            self.prefix = prefix

        def process(self, element):
            print(self.prefix+str(element))

    def __init__(self, label=None,prefix=''):
        super().__init__(label)
        self.prefix = prefix

    def expand(self, input):
        input | beam.ParDo(self._OutputFn(self.prefix))

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())
     | 'Log words' >> Output())