我正在尝试从 GCS 存储桶读取 XML 文件的集合并处理它们，其中集合中的每个元素都是代表整个文件的字符串，但我找不到关于如何完成此操作的合适示例，我也无法理解它来自 Apache Beam 文档，主要是关于 Java 版本的。
我当前的管道如下所示：
p = beam.Pipeline(options=PipelineOptions(pipeline_args))
(p
| 'Read from a File' >> beam.io.Read(training_files_folder)
| 'String To BigQuery Row' >> beam.Map(lambda s:
data_ingestion.parse_method(s))
| 'Write to BigQuery' >> beam.io.Write(
beam.io.BigQuerySink(
known_args.output,
schema='title:STRING,text:STRING,id:STRING',
create_disposition=beam.io.BigQueryDisposition.CREATE_IF_NEEDED,
write_disposition=beam.io.BigQueryDisposition.WRITE_TRUNCATE)))
p.run().wait_until_finish()
我收到的错误消息是：
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.2.1\helpers\pydev\pydevd.py", line 1664, in <module>
main()
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.2.1\helpers\pydev\pydevd.py", line 1658, in main
globals = debugger.run(setup['file'], None, None, is_module)
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.2.1\helpers\pydev\pydevd.py", line 1068, in run
pydev_imports.execfile(file, globals, locals) # execute the script
File "C:/Users/Tomer/PycharmProjects/hyperpartisan/cloud-version/data_ingestion.py", line 135, in <module>
run()
File "C:/Users/Tomer/PycharmProjects/hyperpartisan/cloud-version/data_ingestion.py", line 130, in run
p.run().wait_until_finish()
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\direct_runner.py", line 421, in wait_until_finish
self._executor.await_completion()
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\executor.py", line 398, in await_completion
self._executor.await_completion()
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\executor.py", line 444, in await_completion
six.reraise(t, v, tb)
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\executor.py", line 341, in call
finish_state)
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\executor.py", line 366, in attempt_call
side_input_values)
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\transform_evaluator.py", line 109, in get_evaluator
input_committed_bundle, side_inputs)
File "C:\Users\Tomer\anaconda\envs\hyperpartisan\lib\site-packages\apache_beam\runners\direct\transform_evaluator.py", line 283, in __init__
self._source.pipeline_options = evaluation_context.pipeline_options
AttributeError: 'str' object has no attribute 'pipeline_options'
非常感谢任何帮助。
谢谢
托默
解决了第一个问题：事实证明这不适用于 DirectRunner，将运行器更改为 DataFlowRunner 并替换Read with 从文本读取解决了异常：
p = 束.Pipeline(选项=PipelineOptions(pipeline_args))
(p
| 'Read from a File' >> beam.io.ReadFromText(training_files_folder)
| 'String To BigQuery Row' >> beam.Map(lambda s:
data_ingestion.parse_method(s))
| 'Write to BigQuery' >> beam.io.Write(
beam.io.BigQuerySink(
known_args.output,
schema='title:STRING,text:STRING,id:STRING',
create_disposition=beam.io.BigQueryDisposition.CREATE_IF_NEEDED,
write_disposition=beam.io.BigQueryDisposition.WRITE_TRUNCATE)))
p.run().wait_until_finish()
但现在我看到这种方法为我提供了每个文件中的一行作为管道元素，而我希望将整个文件作为字符串作为每个元素。
不知道该怎么做。我发现这个帖子 https://stackoverflow.com/questions/45920895/read-a-file-from-gcs-in-apache-beam/45946643#45946643但它是用java编写的，不确定它如何与python和gcs版本一起工作。
所以看起来 ReadFromText 不适用于我的用例，而且我不知道如何创建文件管道。
解决方案：
感谢 Ankur 的帮助，我修改了代码以包含从 MatchResult 对象列表转换所需的步骤，这是 GCSFileSystem 返回的字符串 pCollection，每个字符串代表一个文件。
p = beam.Pipeline(options=PipelineOptions(pipeline_args))
gcs = GCSFileSystem(PipelineOptions(pipeline_args))
gcs_reader = GCSFileReader(gcs)
(p
| 'Read Files' >> beam.Create([m.metadata_list for m in gcs.match([training_files_folder])])
| 'metadata_list to filepath' >> beam.FlatMap(lambda metadata_list: [metadata.path for metadata in metadata_list])
| 'string To BigQuery Row' >> beam.Map(lambda filepath:
data_ingestion.parse_method(gcs_reader.get_string_from_filepath(filepath)))
| 'Write to BigQuery' >> beam.io.Write(
beam.io.BigQuerySink(
known_args.output,
schema='title:STRING,text:STRING,id:STRING',
# Creates the table in BigQuery if it does not yet exist.
create_disposition=beam.io.BigQueryDisposition.CREATE_IF_NEEDED,
# Appends data to the BigQuery table
write_disposition=beam.io.BigQueryDisposition.WRITE_APPEND)))
p.run().wait_until_finish()
该代码使用此帮助程序类来读取 gcs 文件：
class GCSFileReader:
"""Helper class to read gcs files"""
def __init__(self, gcs):
self.gcs = gcs
def get_string_from_filepath(self,filepath):
with self.gcs.open(filepath) as reader:
res = reader.read()
return res
