Feeder value not updated in gatling test

Question

I am new to scala and gatling . I am trying to fetch values from feeder and post zip file to service . but ${extensionId} is not been updated with fetched value instead it remain as ${extensionId} . Could some one please help me know If I miss some thing here .

          def installExtension() =
            exec(http("template - Install Extension")
              .post(url + "/v1/extensions")
              .basicAuth("jack", "password")
              .headers(namespaceHeader)
// using testUtils to get InputStream conte
              .body(InputStreamBody(TestUtils.toStream(hashMap.get("${extensionId}").getOrElse(null))))
              .check(status.is( 201)))


 class extmgrSimulations extends Simulation {

          val extensionIds = csv(s"${Configuration.dataDirectory}/extensionId.csv").circular


          val extMgrScenerio = scenario("extensionMgr - Scenario")
            .during(Configuration.duration) {
              exitBlockOnFail(
                group("load-test") {
                  exec(
                    pace(Configuration.paceFrom, Configuration.paceTo),
                    feed(extensionIds),feed(extensionIds)
                      randomSwitch(
                      50.00 -> group("Install and delete") {
                        exec(
                          extmgrChain.installExtension(),
                          extmgrChain.deleteExtension(),
                        )
                      },
                      50.00 -> extmgrChain.listExtension()
                    )
                  )
                }
              )
            }

Answer 1

That can't work. Gatling EL (the ${} syntax in strings) doesn't magically work anywhere. This is explained in the documentation.

Warning

This Expression Language only works on String values being passed to Gatling DSL methods. Such Strings are parsed only once, when the Gatling simulation is being instantiated.

For example queryParam("latitude", session => "${latitude}") wouldn’t work because the parameter is not a String, but a function that returns a String.

Also, queryParam("latitude", "${latitude}".toInt) wouldn’t because the toInt would happen before passing the parameter to the queryParam method.

The solution here would be to pass a function:

session => session("latitude").validate[Int].