Extending JSONata with my own functions

dubnemo · 5 December 2025 15:55

Is there a way in Node-RED to register my own functions so they can be accessed within a JSONata transformation? Other tools like Mulesoft allow you to extend DataWeave by add a jar file containing public Java methods, and I am hoping to do the same with JSONata. There are a number date format, include JDEdwards 'Julian' date, that I would like to perform within the context of JSONata for readability, vs referencing a function node that sets flow context and referencing that via $flowContext.

I am reading this in the JSONata documentation but is not clear. It seems like the registerFunction is the approach, but it would be best to put this in perspective of Node-RED.

Thoughts?

TotallyInformation · 5 December 2025 16:36

I believe that the JSONata implementation in Node-RED is already extended and there is (currently anyway) no option for user extensions.

A possible work-around would be to use JSONata in a function node which I think is possible though I've not tried it myself.

AllanOricil · 5 December 2025 20:39

@dubnemo

create a client-side only plugin and do something like below

github.com/node-red/node-red

packages%2Fnode_modules%2F%40node-red%2Futil%2Flib%2Futil.js

master


      
          function prepareJSONataExpression(value,node) {
              var expr = jsonata(value);
              expr.assign('flowContext', function(val, store) {
                  if (node) {
                      return node.context().flow.get(val, store);
                  }
                  return "";
              });
              expr.assign('globalContext', function(val, store) {
                  if (node) {
                      return node.context().global.get(val, store);
                  }
                  return "";
              });
              expr.assign('env', function(name) {
                  var val = getSetting(node, name, node ? node._flow : null);
                  if (typeof val !== 'undefined') {
                      return val;
                  } else {
                      return "";

This file has been truncated. show original

jsonata seems to be in the global context. Open node-red editor in a browser and see if you can get a reference of jsonata using the browser's console. If you can, then you have to build your plugin and set jsonata as "external" in rollup/vite/webpack

Topic		Replies	Views
Feature Request: Register JSONata function Feature Requests	9	1327	7 March 2019
Revisiting custom functions in Jsonata Feature Requests	14	957	30 August 2022
Documentation for Jsonata usage in common Node-RED nodes Feature Requests documentation , jsonata	9	513	19 June 2023
Jsonata expressions from a separate file? Feature Requests	18	275	29 January 2024
The use of JSONata General	15	7635	31 March 2021

Extending JSONata with my own functions

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