Using Streams in Gatling repeat blocks

Question

I've come across the following code in a Gatling scenario (modified for brevity/privacy):

val scn = scenario("X")
  .repeat(numberOfLoops, "loopName") {
      exec((session : Session) => {
        val loopCounter = session.getTypedAttribute[Int]("loopName")
        session.setAttribute("xmlInput", createXml(loopCounter))
      })
      .exec(
        http("X")
         .post("/rest/url")
         .headers(headers)
         .body("${xmlInput}"))
      )
  }

It's naming the loop in the repeat block, getting that out of the session and using it to create a unique input XML. It then sticks that XML back into the session and extracts it again when posting it.

I would like to do away with the need to name the loop iterator and accessing the session. Ideally I'd like to use a Stream to generate the XML.

But Gatling controls the looping and I can't recurse. Do I need to compromise, or can I use Gatling in a functional way (without vars or accessing the session)?

Answer 1

As I see it, neither numberOfLoops nor createXml seem to depend on anything user related that would have been stored in the session, so the loop could be resolved at build time, not at runtime.

import com.excilys.ebi.gatling.core.structure.ChainBuilder

def addXmlPost(chain: ChainBuilder, i: Int) =
    chain.exec(
        http("X")
            .post("/rest/url")
            .headers(headers)
            .body(createXml(i))
    )

def addXmlPostLoop(chain: ChainBuilder): ChainBuilder =
    (0 until numberOfLoops).foldLeft(chain)(addXmlPost)

Cheers,

Stéphane

PS: The preferred way to ask something about Gatling is our Google Group: https://groups.google.com/forum/#!forum/gatling