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https://issues.apache.org/jira/browse/KAFKA-7052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16939744#comment-16939744
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Gunnar Morling commented on KAFKA-7052:
---------------------------------------
Looking into this, and it's an interesting case. The problem arises when the
SMT gets one of the [schema change
events|https://debezium.io/documentation/reference/0.9/connectors/mysql.html#schema-change-topic]
from the Debezium MySQL connector which don't have the primary key structure
as for instance your customers table. So I think actually it's not your
intention to apply the SMT to these messages to begin with.
Question is how to deal with this case; I could see these options when
encountering a message which doesn't have the given field:
* raise a more meaningful exception than NPE (pretty disruptive)
* return null
* leave the key/value unchanged
I think for your use case, the last option is the most useful one. But
returning null might also make sense in others. This might require an option
perhaps?
> ExtractField SMT throws NPE - needs clearer error message
> ---------------------------------------------------------
>
> Key: KAFKA-7052
> URL: https://issues.apache.org/jira/browse/KAFKA-7052
> Project: Kafka
> Issue Type: Improvement
> Components: KafkaConnect
> Reporter: Robin Moffatt
> Priority: Major
>
> With the following Single Message Transform:
> {code:java}
> "transforms.ExtractId.type":"org.apache.kafka.connect.transforms.ExtractField$Key",
> "transforms.ExtractId.field":"id"{code}
> Kafka Connect errors with :
> {code:java}
> java.lang.NullPointerException
> at
> org.apache.kafka.connect.transforms.ExtractField.apply(ExtractField.java:61)
> at
> org.apache.kafka.connect.runtime.TransformationChain.apply(TransformationChain.java:38){code}
> There should be a better error message here, identifying the reason for the
> NPE.
> Version: Confluent Platform 4.1.1
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