DataWeave 2.2 is compatible and bundled with Mule 4.2. Standard Support for Mule 4.2 ended on May 2, 2021, and this version of Mule will reach its End of Life on May 2, 2023, when Extended Support ends.

Deployments of new applications to CloudHub that use this version of Mule are no longer allowed. Only in-place updates to applications are permitted.

MuleSoft recommends that you upgrade to the latest version of Mule 4 that is in Standard Support so that your applications run with the latest fixes and security enhancements.

sumBy(Array<T>, (T) -> Number): Number

Returns the sum of the values of the elements in an array.


Name Description


The input array.


A DataWeave selector that selects the values of the numbers in the input array.


This example calculates the sum of the values of elements some arrays. Notice that both of the sumBy function calls produce the same result.


 %dw 2.0
 import * from dw::core::Arrays
 output application/json
  "sumBy" : [
    [ { a: 1 }, { a: 2 }, { a: 3 } ] sumBy $.a,
    sumBy([ { a: 1 }, { a: 2 }, { a: 3 } ], (item) -> item.a)


{ "sumBy" : [ 6, 6 ] }

Was this article helpful?

💙 Thanks for your feedback!

Edit on GitHub
Submit your feedback!
Share your thoughts to help us build the best documentation experience for you!
Take our latest survey!