How do I increment a UUID gatling feeder

Question

I am new to gatling and scala, so this is definitely a n00b question but I am struggling to figure this out. I found this great blog post to be able to use a UUID feeder http://www.andrewgorton.uk/blog/gatling-uuid-feeder/

object UuidFeeder {
    val feeder = new Feeder[String] {
        override def hasNext = true

        override def next: Map[String, String] = {
            Map("uuid" -> UUID.randomUUID.toString());
        }
    }
}

This works great, my issue is that I can't figure out how to get a new value, when I put it into a loop.

I am using it like this -

val scn = scenario("Test Scenario")
  .feed(UuidFeeder.feeder)
    .exec(http("get stuff")
                .post("/stuff")
                .body(StringBody(
                """{
                   "uuid": "${uuid}",
                }""")).asJSON
                .check(status.is(201)))

If I use ${uuid} in a subsequent test, it will be the same value. How do I get a new value for the next call?

Flotsam

where do you call UuidFeeder.feeder? can you show us what is before the exec? – Gilda

I added it. it is inside the scenario – Flotsam

I get a "not found: type Feeder" error relating to this piece of code. new Feeder[String] Presumably, I need to import something, but cannot for the life of me find out what. – Tantalus

I found it! :) import io.gatling.core.feeder._ – Tantalus

Answer 1

Your code looks fine to me and should generate different UUIDs for each virtual user every time they reach the feed action.

Official

Seems like this was due to my misunderstanding of how feeds worked, i just needed to call the feed before i used it again it seems. Thanks for the help. – Flotsam

Answer 2

I prefer using the Iterator.continually helper instead like so:

object UuidFeeder {
    val feeder = Iterator.continually(Map("uuid" -> java.util.UUID.randomUUID.toString()))
}

usage would be the same as before.. hope it helps :)

// Usage
//
// scenario("My Scenario")
//      .feed(UuidFeeder.feeder)
//      .exec(http("MyCall"))
//    ...// rest of code

Eddings

Why the down vote.. if I've done something wrong at least let me know.. – Eddings