Source code for apache_beam.yaml.yaml_io

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"""This module contains the Python implementations for the builtin IOs.

They are referenced from standard_io.py.

Note that in the case that they overlap with other (likely Java)
implementations of the same transforms, the configs must be kept in sync.
"""

import os

import yaml

import apache_beam as beam
import apache_beam.io as beam_io
from apache_beam.io import ReadFromBigQuery
from apache_beam.io import WriteToBigQuery
from apache_beam.io.gcp.bigquery import BigQueryDisposition
from apache_beam.typehints.schemas import named_fields_from_element_type
from apache_beam.yaml import yaml_provider


[docs]def read_from_text(path: str): # TODO(yaml): Consider passing the filename and offset, possibly even # by default. return beam_io.ReadFromText(path) | beam.Map(lambda s: beam.Row(line=s))
[docs]@beam.ptransform_fn def write_to_text(pcoll, path: str): try: field_names = [ name for name, _ in named_fields_from_element_type(pcoll.element_type) ] except Exception as exn: raise ValueError( "WriteToText requires an input schema with exactly one field.") from exn if len(field_names) != 1: raise ValueError( "WriteToText requires an input schema with exactly one field, got %s" % field_names) sole_field_name, = field_names return pcoll | beam.Map( lambda x: str(getattr(x, sole_field_name))) | beam.io.WriteToText(path)
[docs]def read_from_bigquery( query=None, table=None, row_restriction=None, fields=None): if query is None: assert table is not None else: assert table is None and row_restriction is None and fields is None return ReadFromBigQuery( query=query, table=table, row_restriction=row_restriction, selected_fields=fields, method='DIRECT_READ', output_type='BEAM_ROW')
[docs]def write_to_bigquery( table, *, create_disposition=BigQueryDisposition.CREATE_IF_NEEDED, write_disposition=BigQueryDisposition.WRITE_APPEND, error_handling=None): class WriteToBigQueryHandlingErrors(beam.PTransform): def default_label(self): return 'WriteToBigQuery' def expand(self, pcoll): write_result = pcoll | WriteToBigQuery( table, method=WriteToBigQuery.Method.STORAGE_WRITE_API if error_handling else None, create_disposition=create_disposition, write_disposition=write_disposition, temp_file_format='AVRO') if error_handling and 'output' in error_handling: # TODO: Support error rates. return { 'post_write': write_result.failed_rows_with_errors | beam.FlatMap(lambda x: None), error_handling['output']: write_result.failed_rows_with_errors } else: if write_result._method == WriteToBigQuery.Method.FILE_LOADS: # Never returns errors, just fails. return { 'post_write': write_result.destination_load_jobid_pairs | beam.FlatMap(lambda x: None) } else: # This should likely be pushed into the BQ read itself to avoid # the possibility of silently ignoring errors. def raise_exception(failed_row_with_error): raise RuntimeError(failed_row_with_error.error_message) _ = write_result.failed_rows_with_errors | beam.Map(raise_exception) return { 'post_write': write_result.failed_rows_with_errors | beam.FlatMap(lambda x: None) } return WriteToBigQueryHandlingErrors()
[docs]def io_providers(): with open(os.path.join(os.path.dirname(__file__), 'standard_io.yaml')) as fin: return yaml_provider.parse_providers(yaml.load(fin, Loader=yaml.SafeLoader))