Kafka Connect ChangeTopicCase SMT Usage Reference for Confluent Cloud

The ChangeTopicCase Single Message Transform (SMT) allows you to automatically modify the case (uppercase, lowercase) of the Kafka topic name before the record is produced or consumed. This SMT converts a topic name, for example, KAFKA_TOPIC to kafkaTopic, or kafka_topic.

Note

The ChangeTopicCase SMT is supported on the JDBC Source, CDC Source, and MongoDB Source connectors.

To apply the ChangeTopicCase SMT, add the following to your connector configuration. Update the placeholders to specify the topic’s current casing (transforms.changeTopicCase.from) and the required output casing (transforms.changeTopicCase.to).

{
  "transforms" : "changeTopicCase",
  "transforms.changeTopicCase.type" : "com.github.jcustenborder.kafka.connect.transform.common.ChangeTopicCase",
  "transforms.changeTopicCase.from" : "<VALID_CASE_NAME>",
  "transforms.changeTopicCase.to" : "<TARGET_CASE_TYPE>"
 }

Examples

The example below shows how to use ChangeTopicCase SMT to convert LOWER_CAMEL to UPPER_UNDERSCORE .

• Before:

  {
    "topic" : "topicName",
    "kafkaPartition" : 1,
    "timestampType" : "NO_TIMESTAMP_TYPE",
    "offset" : 12345,
    "headers" : [ ]
  }
  

• Adding the SMT to your connector configuration:

  To apply the ChangeTopicCase SMT, add the following to your connector configuration:

  {
    "transforms" : "changeTopicCase",
    "transforms.changeTopicCase.type" : "com.github.jcustenborder.kafka.connect.transform.common.ChangeTopicCase",
    "transforms.changeTopicCase.from" : "LOWER_CAMEL",
    "transforms.changeTopicCase.to" : "UPPER_UNDERSCORE"
  }
  

• After:

  After the ChangeTopicCase SMT applies, the value transforms as follows:

  {
    "topic" : "TOPIC_NAME",
    "kafkaPartition" : 1,
    "timestampType" : "NO_TIMESTAMP_TYPE",
    "offset" : 12345,
    "headers" : [ ]
  }
  

Properties

Name	Description	Type	Default	Valid Values	Importance
from	The format of the incoming topic name.	STRING		LOWER_HYPHEN, LOWER_UNDERSCORE, LOWER_CAMEL, UPPER_CAMEL, UPPER_UNDERSCORE	HIGH
to	The format of the outgoing topic name.	STRING		LOWER_HYPHEN, LOWER_UNDERSCORE, LOWER_CAMEL, UPPER_CAMEL, UPPER_UNDERSCORE	HIGH

Predicates

Transformations can be configured with predicates so that the transformation is applied only to records which satisfy a condition. You can use predicates in a transformation chain and, when combined with the Kafka Connect Filter (Kafka) SMT Usage Reference for Confluent Cloud, predicates can conditionally filter out specific records. For details and examples, see Predicates.