How to use JMeter's internal methods (vars.get(), etc.) in Groovy class in JSR223

Question

I write Groovy script in my JSR223 PreProcessor like this

import groovy.json.JsonSlurper;

class jmeter {

   
    def parsingJSON(String fileName){
        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        vars.put("myVar",  object.event_id)

        return object.event_id
    }
}

		def running = new jmeter()
        running.parsingJSON( "C:/Users/payload.json")

this will return exception

ERROR o.a.j.m.JSR223PreProcessor: Problem in JSR223 script, JSR223 PreProcessor Dummy javax.script.ScriptException: javax.script.ScriptException: groovy.lang.MissingPropertyException: No such property: vars for class: jmeter

But when I remove the class , so it looks like this

import groovy.json.JsonSlurper;

    def parsingJSON(String fileName){
        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        vars.put("myVar",  object.event_id)

        return object.event_id
    }
    
        parsingJSON( "C:/Users/payload.json")

It will run without any issue.

My question: I understand vars is JMeter internal API , but can't we use vars.put() or vars.get() in Groovy script using class{} in JSR223 Sampler / PreProcessor in JMeter?

[UPDATE after getting input 1 Jul 19]:

I write the codes in Intellij and looks like this. It runs perfectly fine.

import groovy.json.JsonSlurper
import org.apache.jmeter.threads.JMeterVariables


class jmeter {

    JMeterVariables vars;
    jmeter(JMeterVariables vars) {
        this.vars = vars;
    }

    def parsingJSON(String fileName){
        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        vars.put("myVar",  object.event_id)
        println("My Var " + vars.get("myVar"))

        return object.event_id
    }
}


class runTest {
    static void main(String[] args) {
        JMeterVariables vars = new JMeterVariables();
        def running = new jmeter(vars)
        running.parsingJSON( "C:/Users/payload")
    }
}

The code basically put the value to parameter myVar , so I can use it in my HTTP Request Sampler. I copy paste it to JMeter JSR223 PreProcessor, then create HTTP Request sampler and put ${myVar} in the Body Data

I expect the value of "myVar" will be reflected in the Body Data. But after I run it , I see the parameter ${myVar} in Result Tree Listener , instead of the value.

[UPDATE after getting input from Dmitry 3 July 2019]

I use IntelliJ and write the code like this

import groovy.json.JsonSlurper
import org.apache.jmeter.threads.JMeterVariables

class Global {
    static vars = [:]
}

Global.vars.jmeterVars = vars



class jmeter {

        def parsingJSON(String fileName){
        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        Global.vars.jmeterVars.put("myVar",  object.event_id)  //This will return java.lang.NullPointerException: Cannot invoke method put() on null object
        println("My Var " + vars.get("myVar"))

        return object.event_id
    }
}


class runTest {
    static void main(String[] args) {

        def running = new jmeter()
        running.parsingJSON( "C:/Users/payload")

    }
}

This time even IntelliJ returns me an error

Exception in thread "main" java.lang.NullPointerException: Cannot invoke method put() on null object at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:91) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:43) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.NullCallSite.call(NullCallSite.java:34) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:135) at jmeter.parsingJSON(jmeter.groovy:21) at jmeter$parsingJSON.call(Unknown Source) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127) at runTest.main(jmeter.groovy:38) Basically, the error is caused by Global.vars.jmeterVars.put("myVar", object.event_id)

[UPDATE] : 17 July 2019 with input from user7294900

I wrote the code like this in IntelliJ

import groovy.json.JsonSlurper
import org.apache.jmeter.threads.JMeterVariables


class jmeter2 {

    JMeterVariables vars;

    jmeter2(JMeterVariables vars) {
        this.vars = vars;
    }

    public addvar(String VarName, String value) {
        vars.put(VarName, value);
    }


    def parsingJSON(String fileName) {
        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        addvar("myVar", object.event_id)
        println("My Var " + vars.get("myVar"))

        return object.event_id
    }
}


class runTest {
    static void main(String[] args) {
        
        JMeterVariables vars = new JMeterVariables();
        def running = new jmeter2(vars)
        running.parsingJSON( "C:/Users/payload.json")

    }
}

It works perfectly fine in Intellij. I just need to add some jar dependencies to Intellij (slf4j-simple-1.7.2 , apachejmeter_core , logkit-1.2.2 ). IntelliJ will return the result. So far so good.

I copied paste the code to JMeter , by creating JSR223 sampler , debug sampler , and Results Tree listener.

I can't see any myVar created by JSR223 sampler in the Listener.

JMeter log also doesn't show any issue

2019-07-17 12:33:15,806 INFO o.a.j.s.SampleEvent: List of sample_variables: [] 2019-07-17 12:33:15,806 INFO o.a.j.g.u.JMeterMenuBar: setRunning(true, *local*) 2019-07-17 12:33:15,812 INFO o.a.j.e.StandardJMeterEngine: Starting ThreadGroup: 1 : Thread Group 2019-07-17 12:33:15,812 INFO o.a.j.e.StandardJMeterEngine: Starting 1 threads for group Thread Group. 2019-07-17 12:33:15,812 INFO o.a.j.e.StandardJMeterEngine: Thread will continue on error 2019-07-17 12:33:15,812 INFO o.a.j.t.ThreadGroup: Starting thread group... number=1 threads=1 ramp-up=1 delayedStart=false 2019-07-17 12:33:15,813 INFO o.a.j.t.ThreadGroup: Started thread group number 1 2019-07-17 12:33:15,813 INFO o.a.j.e.StandardJMeterEngine: All thread groups have been started 2019-07-17 12:33:15,813 INFO o.a.j.t.JMeterThread: Thread started: Thread Group 1-1 2019-07-17 12:33:15,825 INFO o.a.j.t.JMeterThread: Thread is done: Thread Group 1-1 2019-07-17 12:33:15,825 INFO o.a.j.t.JMeterThread: Thread finished: Thread Group 1-1 2019-07-17 12:33:15,825 INFO o.a.j.e.StandardJMeterEngine: Notifying test listeners of end of test 2019-07-17 12:33:15,825 INFO o.a.j.g.u.JMeterMenuBar: setRunning(false, *local*)

The file payload.json only contains a very simple json

{
"event_id": "01DE95CRARFQ4X9WEKXACQYHVX",
"event_type": "form_response"
}

I am not sure why JMeter doesn't like the script. Any idea maybe? Thanks.

Answer 1

If you want to add variable(s) you need to pass current JMeterVariables object to jmeter object,

The following code add variable aaa to existing JMeter variables

import org.apache.jmeter.threads.JMeterVariables;
class jmeter {
      JMeterVariables vars;
      jmeter(JMeterVariables vars) {
         this.vars = vars;
      }
public addvar() {
    vars.put("aaa","bbb");
}
}

def running = new jmeter(vars);
running.addvar();

So Intellij recognize JMeterVariables you will have to add ApacheJMeter_core.jar from JMeter's lib\ext folder

Answer 2

If you want to keep your code structure with minimal changes consider introducing a separate class holding static variables which will be accessible everywhere in your Groovy script.

Something like:

import groovy.json.JsonSlurper

class Global {
    static vars = [:]
}

Global.vars.jmeterVars = vars

class jmeter {


    def parsingJSON(String fileName) {

        def payload = new File(fileName).getText();
        def jsonSlurper = new JsonSlurper()
        def object = jsonSlurper.parseText(payload)

        Global.vars.jmeterVars.put("myVar", object.event_id)

        return object.event_id
    }
}

def running = new jmeter()
running.parsingJSON("C:/Users/payload.json")

More information:

• Groovy Goodness: Variable Scope in Scripts
• Groovy: Object orientation
• Top 8 JMeter Java Classes You Should Be Using with Groovy