ExecuteScript - flowFile with new attributes not sent to next processor

[#1]

I have a GenerateFlowFile processor that sends a flowFile to the ExecuteScript processor. In the ExecuteScript processor, I added a new attribute and value to the incoming flowFIle. But this updated flowFIle is not output to the next processor

Incoming FlowFile content from GenerateFlowFile

{'name':'myName'}

ExecuteScript script body

var flowFile = session.get();
if (flowFile != null) {
	try {
		flowFile = session.putAttribute(flowFile, 'gender', 'male');
		session.transfer(flowFile, REL_SUCCESS);
	} catch (e) {
		session.transfer(flowFile, REL_FAILURE);
	}
}

Output to next processor

{'name':'myName'}

Am I missing something??

[#2]

Hello,

in your script body you dont manipulate the content.

You add an Attribute to your flowfile (which works 😀) 

Maybe you can have a look at https://community.cloudera.com/t5/Community-Articles/ExecuteScript-Cookbook-part-2/ta-p/249018/page/...

But in case you don´t need to do it via ExecuteScript Processor, you could use JoltTransformJSON Processor.

On conficuration you can set for the property Jolt Specification following value:

[
  {
    "operation": "default",
    "spec": {
      "gender": "male"
    }
  }
]

 After that your JSON should be extended with your key-value-pair.

Greetings

[#3 · Accepted solution]

Hi,

Thank you for pointing that out. It has certaintly speed up my development.

This is a short snippet to my solution:

var StreamCallback =  Java.type("org.apache.nifi.processor.io.StreamCallback");
var IOUtils = Java.type("org.apache.commons.io.IOUtils");
var StandardCharsets = Java.type("java.nio.charset.StandardCharsets");

var flowFile = session.get();
if(flowFile != null) {
	try {
	  // Create a new StreamCallback, passing in a function to define the interface method
	  flowFile = session.write(flowFile,
	    new StreamCallback(function(inputStream, outputStream) {
	        var text = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
					var obj = JSON.parse(text);
					obj["gender"] = "Male";
					outputStream.write(JSON.stringify(obj).getBytes(StandardCharsets.UTF_8));
	    }));
		session.transfer(flowFile, REL_SUCCESS);
	} catch (e) {
			log.error(e.message)
			session.transfer(flowFile, REL_FAILURE);
	}
}

Something to point out for those using javascript. If your using GenerateFlowFile processor to generate sample JSON content, the JSON content in Custom Text must use double quotes ( " ), not single quotes ( ' ). I spent an hour debugging why my JSON.parse(text) didn't work.

Custom Text

{'name':'myName'}

It should be

{"name":"myName"}