Shred JSON into context variables

extractJsonToContextVars.js

// extractJsonToContextVars.js
// ------------------------------------------------------------------
//
// For a JSON payload, set context vars for all fields.
//
/* global context, properties */

var what = Object.prototype.toString;

function walkObj(obj, path, fn) {
  var wo = what.call(obj), p;
  path = path || '';

  if (wo == "[object Object]") {
    Object.keys(obj).forEach(function(key){
      var item = obj[key], w = what.call(item);
      var pathelts = path.split('.');
      pathelts.push(key);
      var newpath = pathelts.join('.');
      if (w == "[object Object]" || w == "[object Array]") {
        walkObj(item, newpath, fn);
      }
      else {
        fn(newpath, item);
      }
    });
  }
  else if (wo == "[object Array]") {
    obj.forEach(function(item, ix){
      var w = what.call(item);
      var pathelts = path.split('.');
      pathelts.push('['+ix+']');
      var newpath = pathelts.join('.');
      if (w == "[object Object]" || w == "[object Array]") {
        walkObj(item, newpath, fn);
      }
      else {
        fn(newpath, item);
      }
    });
  }
  else {
    var msg  = "Unknown object to convert: " + wo + "("+ JSON.stringify(obj, null, 2).slice(0, 34) +")";
    //console.log(msg);
    throw {error: true, message: msg };
  }
}

var sourceVariable = properties.source || 'message.content';
var outputVarPrefix = properties['output-prefix'] || 'json';
try {
  var obj = JSON.parse(context.getVariable(sourceVariable));
  walkObj(obj,
          outputVarPrefix,
          function(name, value) {
            context.setVariable(name, value);
          });
}
catch (e) {
  context.setVariable(outputVarPrefix + '.error', "bad inbound message");
  context.setVariable(outputVarPrefix + '.exception', e.toString());
}

JS-ShredJSON.xml

<Javascript name='JS-ShredJSON' timeLimit='200' >
  <Properties>
    <Property name='output-prefix'>private</Property>
    <Property name='source'>ContextVariableContainingJSON</Property>
  </Properties>
  <ResourceURL>jsc://extractJsonToContextVars.js</ResourceURL>
</Javascript>