# Why foreignKeyExtractor does not accept key?

**URL:** <https://forum.confluent.io/t/why-foreignkeyextractor-does-not-accept-key/12427>\
**Category:** Kafka Streams\
**Created:** [25 October 2024 16:04 UTC](https://forum.confluent.io/t/why-foreignkeyextractor-does-not-accept-key/12427 "2024-10-25T16:04:00Z")\
**Posts on this page:** 1\
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**Author:** ![mjsax](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.confluent.io/mjsax/32/3113_2.png) [@mjsax](https://forum.confluent.io/u/mjsax)\
**Post date:** [25 October 2024 17:24 UTC](https://forum.confluent.io/t/why-foreignkeyextractor-does-not-accept-key/12427/2 "2024-10-25T17:24:39Z")

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Good point. I think it’s just a oversight in the design of FK join. I don’t see any reason why we would need to limit the FK-extractor to only user the value as input.

Can you file a Jira ticket for this?

I cannot think of any other workaround right now, but believe what you do (duplicate the FK key column into the value) is the only way to make it work right now.

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