Important

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ExtractTopic

The following provides usage information for the Confluent SMT io.confluent.connect.transforms.ExtractTopic.

Description

Extract data from a message and use it as the topic name. You can either use the entire key/value (which should be a string), or use a field from a map or struct. Use the concrete transformation type designed for the record key (io.confluent.connect.transforms.ExtractTopic$Key) or value (io.confluent.connect.transforms.ExtractTopic$Value).

Installation

This transformation is developed by Confluent and does not ship by default with Apache Kafka® or Confluent Platform. You can install this transformation via the Confluent Hub Client:

confluent-hub install confluentinc/connect-transforms:latest

Examples

The configuration snippet below shows how to use and configure the ExtractTopic SMT.

transforms=KeyExample, ValueFieldExample, KeyFieldExample, FieldJsonPathExample

Use the key of the message as the topic name.

transforms.KeyExample.type=io.confluent.connect.transforms.ExtractTopic$Key

Extract a required field named f2 from the value, and use it as the topic name.

transforms.ValueFieldExample.type=io.confluent.connect.transforms.ExtractTopic$Value
transforms.ValueFieldExample.field=f2

Extract a field named f3 from the key, and use it as the topic name. If the field is null or missing, leave the topic name as-is.

transforms.KeyFieldExample.type=io.confluent.connect.transforms.ExtractTopic$Value
transforms.KeyFieldExample.field=f3
transforms.KeyFieldExample.skip.missing.or.null=true

Extract the value of a field named f3 in the f1 field in the key, and use it as the topic name. Here the format of the field is defined with JSON Path (e.g., ["f1"]["f3"]). If the field is null or missing, leave the topic name as-is.

transforms.FieldJsonPathExample.type=io.confluent.connect.transforms.ExtractTopic$Value
transforms.FieldJsonPathExample.field=$["f1"]["f3"]
transforms.FieldJsonPathExample.field.format=JSON_PATH
transforms.FieldJsonPathExample.skip.missing.or.null=true

Properties

Name	Description	Type	Default	Valid Values	Importance
field	Field name to use as the topic name. If left blank, the entire key or value is used (and assumed to be a string).	string	“”		medium
field.format	Specify field path format. Currently two formats are supported: JSON_PATH and PLAIN. If set to JSON_PATH, the transformer will interpret the field with JSON path intepreter, which supports nested field extraction. If left blank or set to PLAIN, the transformer will evaluates field config as non-nested field name.	string	“PLAIN”	“JSON_PATH”, “PLAIN”	medium
skip.missing.or.null	How to handle missing fields and null fields, keys, and values. By default, this transformation will throw an exception if a field specified via the field configuration is missing or null, or if no field is specified but the message’s key or value is null. If this configuration is set to true, the transformation will instead silently ignore these conditions and allow the record to pass through unaltered.	boolean	false		low