DataWeave 2.1 is compatible with Mule 4.1. Standard Support for Mule 4.1 ended on November 2, 2020, and this version of Mule will reach its End of Life on November 2, 2022, 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.

mergeWith(T, V): ?

Appends any key-value pairs from a source object to a target object.

If source and target objects have the same key, the function appends that source object to the target and removes that target object from the output.


Name Description


The object to append to the target.


The object to which the source object is appended.


This example appends the source objects to the target. Notice that "a" : true, is removed from the output, and "a" : false is appended to the target.


%dw 2.0
import mergeWith from dw::core::Objects
output application/json
{ "mergeWith" : { "a" : true, "b" : 1} mergeWith { "a" : false, "c" : "Test"} }


"mergeWith": {
    "b": 1,
    "a": false,
    "c": "Test"

mergeWith(Null, T): T

Helper method to make mergeWith null friendly.

mergeWith(T, Null): T

Helper method to make mergeWith null friendly.

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