Workato format_map issue: null returned as string instead of JSON null

shaked — Mon, 25 May 2026 09:14:21 GMT

I’m working with a dynamic list in Workato and building a JSON string using format_map.

My current formula looks like this:

='{' +
( _dp('...ResponseBody...') == null ? '' :
  _dp('...ResponseBody...').format_map('"%{Key}":"%{Value}"').join(',')
) +
'}'

The issue is that when the value is null, the output becomes:

{"data":"null"}

However, I need it to be valid JSON, like this:

{"data":null}

In addition, I need proper type handling:

Strings should be wrapped in quotes
Numbers and booleans should not be wrapped in quotes
Null values should be actual JSON null (without quotes)

Is there a recommended way in Workato to handle this type-aware formatting inside format_map, or any other approach to correctly build a valid JSON object from a dynamic list?

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Workato format_map issue: null returned as string instead of JSON null