How to run the request based on previous request response data - jmeter

Question

I have test plan with following request in sequence with 2 loops.
ApiHttp request
Mqtt request
I need to run 1st loop & verify API reaponse is true or false:
If it's true, run Mqtt request , else start the 2nd loop and same verify the API response, if it's true run Mqtt else stop.
In above scenarios, I put beanshell to read the API response:
vars.put("response", new String(data));
But don't know how to verify of its true or false & execute the Mqtt. Any help pls.

Answer 1

Add If Controller as the very first test element under the Thread Group and use the __groovy() function as the condition:
${__groovy(vars.getIteration() <= 2,)}
Put ApiHttp request as a child of the If Controller
Add another If Controller after the ApiHttp request and use the following __groovy() function as the condition:
${__groovy(ctx.getPreviousResult().getResponseDataAsString().contains('true'))}
Add Mqtt request as a child of the If Controller
Add Flow Control Action sampler after the Mqtt request and configure it like:

Answer 2

First switch from Beanshell to JSR223 Test elements and use Groovy.
Use If Controller and just put in it:
${response}
To stop the test based on iteration number, be aware that a Loop Controller exposes iteration as a variable based on name of variable, for example if your LoopController is named LC, then you can access iteration as:
vars["__jm__LC__idx"].toInteger()
And to stop a test from Groovy using JSR223 Assertion you can throw:
throw new org.apache.jorphan.util.JMeterStopTestException();
See:
https://jmeter.apache.org/api/org/apache/jorphan/util/JMeterStopTestException.html