| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you under the Apache License, Version 2.0 (the |
| # "License"); you may not use this file except in compliance |
| # with the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| import apache_beam as beam |
| |
| |
| class LogElements(beam.PTransform): |
| |
| class _LoggingFn(beam.DoFn): |
| |
| def __init__(self, prefix=''): |
| super(LogElements._LoggingFn, self).__init__() |
| self.prefix = prefix |
| |
| def process(self, element, **kwargs): |
| print(self.prefix + str(element)) |
| yield element |
| |
| def __init__(self, label=None, prefix=''): |
| super(LogElements, self).__init__(label) |
| self.prefix = prefix |
| |
| def expand(self, input): |
| input | beam.ParDo(self._LoggingFn(self.prefix)) |