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Dian Fu commented on FLINK-25513: --------------------------------- [~atptour2017] Thanks for reporting this issue. Would you like to take it? > CoFlatMapFunction requires both two flat_maps to yield something > ---------------------------------------------------------------- > > Key: FLINK-25513 > URL: https://issues.apache.org/jira/browse/FLINK-25513 > Project: Flink > Issue Type: Bug > Components: API / Python > Affects Versions: 1.13.3 > Reporter: chendan > Priority: Major > > When I used CoFlatMapFunction is pyflink, I found out that I must put yield > something in both flat_map1 and flat_map2. Otherwise, it will raise an > exception: TypeError: 'NoneType' object is not iterable. > In pyflink source code: datastream.py, the process_element2 of > KeyedCoMapCoProcessFunction class in ConnectedStreams class has only one > sentence: > {color:#cc7832}yield > {color}{color:#94558d}self{color}._underlying.map2(value). if the flat_map2 > has not yield something it will result in exception. So it should judge > whether the {color:#94558d}self{color}._underlying.map2(value) is None or not > firstly. -- This message was sent by Atlassian Jira (v8.20.1#820001)