Flatten

The flatten transform function converts structured, nested data into a new single-hierarchy-level structured data.
The names of the new fields are built by concatenating the intermediate level field names.
The step name is flatten, and the UserConfig is controlled here: UserConfig: {"steps": [{"type": "flatten"}]}.

Parameters:

Parameter Description

Parameter	Description
delimiter	The delimiter to use when concatenating the field names (default: _)
part	when used with KeyValue data, defines if the transform function is done on the `key` or on the `value`. If `null` or absent the transform function applies to both the key and the value.

delimiter

The delimiter to use when concatenating the field names (default: _)

part

when used with KeyValue data, defines if the transform function is done on the key or on the value. If null or absent the transform function applies to both the key and the value.

Example

Produce an AVRO message with the payload: {field1: {field11: value11, field12: value12}}.

AVRO
Result

{"field1": {"field11": "value11", "field12": "value12"}}

{"field1_field11": "value11", "field1_field12": "value12"}

The function flattens the fields with the default delimiter between values, and outputs {field1_field11: value11, field1_field12: value12} to the output topic.

What’s next?

For more, see Transform Functions or the Pulsar documentation.