JMeter BeanShell PreProcessor modify request

Question

I have a JMeter HTTP-Request element which performs a POST call like:

{
  "id" : 1,
  "name" : "me"
}

I want to load this request body on a BeanShell PreProcessor and modify the name field, how can I achieve this?

Answer 1

Answering my own question:

1. Get Request Body:

   String requestBody = sampler.getArguments().getArgument(0).getValue();

2. Modify request(In my case I modified it as a parsed JSONObject)

3. Set the modified request body into the current request:

   sampler.getArguments().getArgument(0).setValue(modifiedRequestObject.toString());

Answer 2

Since JMeter 3.1 you're supposed to be using JSR223 Test Elements and Groovy language for scripting so I would recommend re-considering your "Beanshell" approach.

Here is a piece of sample Groovy code showing how you can amend the request:

def payload = new groovy.json.JsonSlurper().parseText(sampler.getArguments().getArgument(0).getValue())

payload.name = 'some new name'

sampler.getArguments().clear()
sampler.addNonEncodedArgument('', new groovy.json.JsonBuilder(payload).toPrettyString(), '')
sampler.setPostBodyRaw(true)

More information:

• Apache Groovy - Parsing and producing JSON
• Apache Groovy - Why and How You Should Use It