Kafka Connect Cast SMT Usage Reference for Confluent Platform¶
The following provides usage information for the Apache Kafka® SMT org.apache.kafka.connect.transforms.Cast.
Description¶
Cast fields (or the entire key or value) to a specific type, updating the schema if one is present. For example, this can be used to force an integer field into an integer of smaller width. Only simple primitive types are supported, such as integer, float, boolean, and string.
Use the concrete transformation type designed for the record key (org.apache.kafka.connect.transforms.Cast$Key) or value (org.apache.kafka.connect.transforms.Cast$Value).
Examples¶
Cast can transform an entire primitive key/value or one or more fields of a
complex (Struct or Map) key or value. The two configuration snippet examples
below show how to use Cast in these two scenarios.
Cast Value¶
This example shows how to use Cast to transform a 64-bit floating point
value into a string.
"transforms": "Cast",
"transforms.Cast.type": "org.apache.kafka.connect.transforms.Cast$Value",
"transforms.Cast.spec": "string"
Before: 63521704.02
After: "63521704.02"
Cast Comma-Separated Values¶
This example shows how to use Cast with a complex key or value. It shows a
comma-separated field:type pair, where field is the name of the field to
cast and type is the type to cast the field into.
"transforms": "Cast",
"transforms.Cast.type": "org.apache.kafka.connect.transforms.Cast$Value",
"transforms.Cast.spec": "ID:string,score:float64"
The before and after example below shows a Map or Struct with an ID field of
46290 and a score field of 4761. The ID field is cast into a
string and the score field is cast into a 64-bit floating point value.
Before:
{"ID": 46920,"score": 4761}
After:
{"ID": "46290","score": 4761.0}
Tip
For additional examples, see Cast for managed connectors.
Properties¶
| Name | Description | Type | Default | Valid Values | Importance |
|---|---|---|---|---|---|
spec |
A single type to cast the entire value, or for Maps and Structs the comma-separated list of field names and the type to which they should be cast, of the form field1:type1,field2:type2. Valid types are int8, int16, int32, int64, float32, float64, boolean, and string. |
list | comma-separated list of colon-delimited pairs of field:type, e.g. foo:int32,bar:string |
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 Platform, predicates can conditionally filter out specific records. For details and examples, see Predicates.