How to increment a variable in Gatlling Loop - gatling

Question

I am trying to write a Gatling script where I read a starting number from a CSV file and loop through, say 10 times. In each iteration, I want to increment the value of the parameter.
It looks like some Scala or Java math is needed but could not find information on how to do it or how and where to combine Gatling EL with Scala or Java.
Appreciate any help or direction.
var numloop = new java.util.concurrent.atomic.AtomicInteger(0)
val scn = scenario("Scenario Name")
.asLongAs(_=> numloop.getAndIncrement() <3, exitASAP = false){
feed(csv("ids.csv")) //read ${ID} from the file
.exec(http("request")
.get("""http://finance.yahoo.com/q?s=${ID}""")
.headers(headers_1))
.pause(284 milliseconds)
//How to increment ID for the next iteration and pass in the .get method?
}

Answer 1

You copy-pasted this code from Gatling's Google Group but this use case was very specific.
Did you first properly read the documentation regarding loops? What's your use case and how doesn't it fit with basic loops?
Edit: So the question is: how do I get a unique id per loop iteration and per virtual user?
You can compute one for the loop index and a virtual user id. Session already has a unique ID but it's a String UUID, so it's not very convenient for what you want to do.
// first, let's build a Feeder that set an numeric id:
val userIdFeeder = Iterator.from(0).map(i => Map("userId" -> i))
val iterations = 1000
// set this userId to every virtual user
feed(userIdFeeder)
// loop and define the loop index
.repeat(iterations, "index") {
// set an new attribute named "id"
exec{ session =>
val userId = session("userId").as[Int]
val index = session("index").as[Int]
val id = iterations * userId + index
session.set("id", id)
}
// use id attribute, for example with EL ${id}
}

Answer 2

Here is my answer to this:
Problem Statement: I had to repeat the gatling execution for configured set of times, and my step name has to be dynamic.
object UrlVerifier {
val count = new java.util.concurrent.atomic.AtomicInteger(0)
val baseUrl = Params.applicationBaseUrl
val accessUrl = repeat(Params.noOfPagesToBeVisited,"index") {
exec(session=> {
val randomUrls: List[String] = UrlFeeder.getUrlsToBeTested()
session.set("index", count.getAndIncrement).set("pageToTest", randomUrls(session("index").as[Int]))
}
).
exec(http("Accessing Page ${pageToTest}")
.get(baseUrl+"${pageToTest}")
.check(status.is(200))).pause(Params.timeToPauseInSeconds)
}
So basically UrlFeeder give me list of String (urls to be tested) and in the exec, we are using count (AtomicInteger), and using this we are populating a variable named 'index' whose value will start from 0 and will be getAndIncremented in each iteration. This 'index' variable is the one which will be used within repeat() loop as we are specifying the name of counterVariable to be used as 'index'
Hope it helps others as well.