如何使用ApacheBeam Python将输出写入动态路径

Question

我是阿帕奇·比姆的新手。我的场景如下所示

我有多个json格式的事件。在每个事件中，event_time列指示该事件的创建时间，我使用event_time计算它们的创建日期。 我想把这些事件分别写在它们的日期分区下。我的代码是

import apache_beam as beam
from apache_beam.io import WriteToText
from apache_beam.pvalue import TaggedOutput
import json
import time


class EventFormatter(beam.DoFn):

  def process(self, element, *args, **kwargs):
    tmp_dict = {}
    for i in range(len(element['properties'])):
        tmp_dict['messageid'] = element['messageid']
        tmp_dict['userid'] = element['userid']
        tmp_dict['event_time'] = element['event_time']
        tmp_dict['productid'] = element['properties'][i]['productid']

        yield tmp_dict


class DateParser(beam.DoFn):

    def process(self, element, *args, **kwargs):
        key = time.strftime('%Y-%m-%d', time.localtime(element.get('event_time')))
        print(key, element)
        yield TaggedOutput(time.strftime('%Y-%m-%d', time.localtime(element.get('event_time'))), element)


with beam.Pipeline() as pipeline:
  events = (
      pipeline
      | 'Sample Events' >> beam.Create([
          {"messageid": "6b1291ea-e50d-425b-9940-44c2aff089c1", "userid": "user-78", "event_time": 1598516997, "properties": [{"productid": "product-173"}]},
          {"messageid": "b8b14eb3-8e39-42a3-9528-a323b10a7686", "userid": "user-74", "event_time": 1598346837, "properties": [{"productid": "product-143"},{"productid": "product-144"}]}
        ])
      | beam.ParDo(EventFormatter())
      | beam.ParDo(DateParser())
  )


  output = events | "Parse Date" >> WriteToText('/Users/oguz.aydin/Desktop/event_folder/date={}/'.format(....))

我找不到应该如何完成格式块。当我运行代码打印结果时，它给出

('2020-08-27', {'productid': 'product-173', 'userid': 'user-78', 'event_time': 1598516997, 'messageid': '6b1291ea-e50d-425b-9940-44c2aff089c1'})
('2020-08-25', {'productid': 'product-143', 'userid': 'user-74', 'event_time': 1598346837, 'messageid': 'b8b14eb3-8e39-42a3-9528-a323b10a7686'})
('2020-08-25', {'productid': 'product-144', 'userid': 'user-74', 'event_time': 1598346837, 'messageid': 'b8b14eb3-8e39-42a3-9528-a323b10a7686'})

例如。我想在date=2020-08-25文件夹下写两个事件，另一个是date=2020-08-27

在一天结束时，我想把每个事件写在他们的创建日期文件夹下

我该怎么做

谢谢你的帮助

奥古斯

Answer 1

具体地说，要为每个键编写几个元素，可以执行以下操作

class WriteByKey(apache_beam.DoFn):
    def process(self, kvs):
         # All values with the same key will come in at once.
         key, values = kvs
         with beam.io.gcp.gcsio.GcsIO().open(f'gs://bucket/path/{key}.extension', 'w') as fp:
             for value in values:
                 fp.write(value)
                 fp.write('\n')

with beam.Pipeline() as pipeline:
  events = (
      pipeline
      | ...
      | beam.ParDo(EventFormatter())
      | beam.ParDo(DateParser())
  )
  output = events | beam.GroupByKey() | beam.ParDo(WriteByKey())

请注意，运行程序可能需要在失败时重试元素，因此更安全的方法不是直接写入输出，而是写入临时文件，然后在成功时自动重命名它，例如

class WriteByKey(apache_beam.DoFn):
    def process(self, kvs):
         # All values with the same key will come in at once.
         key, values = kvs
         nonce = random.randint(1, 1e9)
         path = f'gs://bucket/path/{key}.extension'
         temp_path = f'{path}-{nonce}'
         with beam.io.gcp.gcsio.GcsIO().open(temp_path, 'w') as fp:
             for value in values:
                 fp.write(value)
                 fp.write('\n')
         beam.io.gcp.gcsio.GcsIO().rename(temp_path, path)

Answer 2

在代码中，您使用了多个输出。 这意味着将一个DoFn（ParDo）的输出连接到另一个DoFn，这对于整个管道来说是静态的

如果您希望根据所拥有的内容将数据转储到不同的文件中，则必须实现一个DoFn，以便进行写入

大概是这样的：

class WriteByKey(apache_beam.DoFn):
   def process(self, kv):
        key, value = kv
        with beam.io.gcp.gcsio.GcsIO().open(f'gs://bucket/path/{key}.extension', 'a') as fp:
            fp.write(value)

     

您应该更改DataParser DoFn以生成一个元组（日期、值）而不是TaggedOut，并将管道更改为如下内容：

with beam.Pipeline() as pipeline:
  events = (
      pipeline
      | 'Sample Events' >> beam.Create([
          {"messageid": "6b1291ea-e50d-425b-9940-44c2aff089c1", "userid": "user-78", "event_time": 1598516997, "properties": [{"productid": "product-173"}]},
          {"messageid": "b8b14eb3-8e39-42a3-9528-a323b10a7686", "userid": "user-74", "event_time": 1598346837, "properties": [{"productid": "product-143"},{"productid": "product-144"}]}
        ])
      | beam.ParDo(EventFormatter())
      | beam.ParDo(DateParser()) | beam.ParDo(WriteByKey())
  )