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How to use avro native decoder when using a PollableMessageSource input in spring cloud stream?

I’m using a PollableMessageSource input to read from a Kafka topic. Messages on that topic are in Avro. use-native-decoding was set to true when those messages were published.

This is how I’m polling:

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pollableChannels is just an injected instance of this interface:

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After seeing that the TypeClassName is not being formed properly (it’s nested objects are set to null by mistake), I started debugging the poll method and I found that it’s relying on the contentType header to select a converter, and since this has not been set (because the messages have been encoded natively), it’s falling back to using the ApplicationJsonMessageMarshallingConverter which is clearly not the right option.

If I use a regular streamListener, the use-native-decoding config property is honored fine, so the messages seem to be published ok.

Therefore, my primary question here is how to force native decoding when using pollable consumers? My borader question could be asking if properties under spring.cloud.stream.bindings.channel-name.consumer are respected at all when using a pollable consumer?

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Update:

Relevant config:

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Answer

The ParameterzedTypeReference. argument is intended to help the message converter to convert the payload to the required type. When using native decoding, the “conversion” is done by the deserializer instead and conversion is not necessary.

So, just remove the second argument to the poll() method and conversion will be skipped.

That said, starting with version 3.0.8 (and Spring Framework 5.2.9), the conversion is a no-op, as can be seen in the example below.

However, it’s still more efficient to omit the argument to avoid any attempt at conversion.

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I just tested it without any problems (tested on 3.0.8, but I don’t believe there have been any changes in this area). In fact, you don’t even need useNativeDecoding for this case.

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