CODEWITHSUNDEEP
apache-kafkaapache-kafka-streams
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Reputation: 111

Missing key when writing to topic

Using the Java Kafka Streams API. I want to select a new key for a topic I'm consuming. The new key will be of a different type. When I use the console consumer to consume the topic with the new key, I can only see the values.

valueStream
    .map((key, value) -> new KeyValue(value.getBook_id(), value))
    .peek((key, value) -> {
        System.out.println("key: " + key); // prints key as expected
        System.out.println("value: " + value); // prints value as expected
    })
    .to("foobartopic", 
        Produced.with(Serdes.Integer(),bookValueIntSerde));

Result of consuming "foobartopic" actual result

The expected result is the same but with a non blank key.

Upvotes: 1

Views: 733

Answers (1)

Bartosz Wardziński
Bartosz Wardziński

Reputation: 6593

Your producer uses Serdes.Integer for key serialization, so to print key in user friendly format by kafka-console-consumer you have to set --key-deserializer to appropriate value. In your case it is org.apache.kafka.common.serialization.IntegerDeserializer.

./kafka/bin//kafka-console-consumer.sh --bootstrap-server :9092 --property print.key=true --from-beginning --topic foobartopic --key-deserializer=org.apache.kafka.common.serialization.IntegerDeserializer

Upvotes: 2

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