You can enter the functions at last of a path, the input to a function is the output of the path expression. The function output transcripts the function itself to use the function place after the path and argument, to pass the functions. For example: $

Following table contains all the functions supported by the JSON Path library:
Function Description Return type
min() Provide the min value of an array of numbers. Double
max() Provide the max value of an array of numbers. Double
avg() Provide the average value of an array of numbers. Double
stddev() Provide the standard deviation value of an array of numbers. Double
length() Provide the length of an array. Integer
sum() Provide the sum value of an array of numbers. Double
keys() Provide the property keys (An alternative for terminal tilde ~). Set<E>
concat(X) Provide a concatenated version of the path output with a new item. Same as input
append(X) Add an item to the json path output array. Same as input

Custom Functions

A custom function for date transform is present in the Kafka Mapper, which takes a String input parameter which denotes the source date format use of the function $.timestamp.transform_date(\"yyyy-MM-dd HH:mm\").

If the date format is present in the JSON data itself, then use $.timestamp.transform_date($.dateFormat)

For example, some of the supported date time formats:
Format Example
yyyy-MM-dd*HH:mm:ss 2022-07-04*13:23:55
yyyy-MM-dd*HH:mm:ss:SSS 2022-10-30*02:47:33:899
yy-MM-dd HH:mm:ss SSS 22-06-26 02:31:29 573
yyyy MMM dd HH:mm:ss.SSS*zzz 2018 Apr 13 22:08:13.211*PDT
Note: Other supported and pre-defined date time formats are present in the Java 11 date time library.