#try

Evaluates an expression, and if it fails, evaluates a lambda with the exception and returns that result instead.

#try(expression, @e: fallback)

Category Control flowValid in Property value

Parameters

Name	Type	Description
expression	any	The expression to attempt.
fallback	lambda	Receives the error as @e (with message, exceptionType and, for errors raised by Jolt, a code such as JLT563) and returns the replacement value.

Returns

any

Examples

Fall back to a default

source.json

{
    "stringValue": "not a number",
    "defaultValue": 0
}

transformer.json

{
    "result": "#try(#valueOf($.stringValue)->#toInteger(), @e: #valueOf($.defaultValue))"
}

output.json

{
    "result": 0
}

Try it in the playground →

Choose a fallback by error code

source.json

{
    "name": "Jolt"
}

transformer.json

{
    "result": "#try(#toUpperCase($.nickname), @e: #if(@e.code == 'JLT563', 'no nickname', 'invalid nickname'))"
}

output.json

{
    "result": "no nickname"
}

Try it in the playground →

Related

#toInteger