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Richard Yu edited comment on KAFKA-4217 at 9/1/17 2:29 AM: ----------------------------------------------------------- [~guozhang] The flatTransform method that you mentioned earlier suggests that there is no mapper in the the method input parameters. If the method does not have a mapper, it will be the same as the regular transform method. Should there be a default mapper, or is one given to the method? was (Author: yohan123): [~guozhang] The flatTransform method that you mentioned earlier suggests that there is no mapper in the the method input parameters. If the method does not have a mapper, it will be the same as the regular transfer method. Should there be a default mapper, or is one given to the method? > KStream.transform equivalent of flatMap > --------------------------------------- > > Key: KAFKA-4217 > URL: https://issues.apache.org/jira/browse/KAFKA-4217 > Project: Kafka > Issue Type: Improvement > Components: streams > Affects Versions: 0.10.0.1 > Reporter: Elias Levy > Labels: api, needs-kip, newbie > > {{KStream.transform}} gives you access to state stores while allowing you to > return zero or one transformed {{KeyValue}}. Alas, it is unclear what method > you should use if you want to access state stores and return zero or multiple > {{KeyValue}}. Presumably you can use {{transform}}, always return {{null}}, > and use {{ProcessorContext.forward}} to emit {{KeyValues}}. > It may be good to introduce a {{transform}}-like {{flatMap}} equivalent, or > allow store access from other {{KStream}} methods, such as {{flatMap}} itself. -- This message was sent by Atlassian JIRA (v6.4.14#64029)