Gatling: loop x times pulling values from a feeder

Question

I'd like to achieve something along these lines

• Load scenario with user from a user feeder
• Perform a login for the user
• Perform a limited number (in a loop) of http calls from another different, random, feeder

Is what I'm asking achievable? With Feeds?? Here is an outline of what I have but without the bit where in each iteration of the loop I can get data from another feed:

val userFeeder = csv( "users.csv" )
val randomPagesFeeder = csv( "pages.csv" ).random

object login {
  val dologin = exec(
    http("login page")
      .get("/login")
      .headers(standardHeaders)
    )
    .exec(
      http("post login form")
        .post("/loginaction")
        .headers(standardHeaders)
        .formParam("loginid","${loginid}")
        .formParam("password", "${password}")
    )

  )
)

object randompages {
  val visitrandom = repeat(10){
     // ??? how to pull from feeder in here so that exec( http ) calls
     // have data from randomPagesFeeder, i.e.:
    exec(
      http("randompage")
        .get("${uriFromAFeeder}")
    )
  }
)

def myload() = {
    feed( userFeeder ).exec( login.dologin, randompages.visitrandom )
}
val scn = scenario( "My scenario" ).exec( myload() )

setUp( scn.inject( rampUsers( userCount ).during( userWarmup.toInt seconds ) ) ).protocols( httpProtocol )

I suspect that this is a simple problem and the answer is in front of me. I have spent a long time with the docs and other tutorials and am hitting a wall of understanding.

Answer 1

The understanding that I was missing was how feeders work. When you call feed( feeder ), you are pulling the next value(s) from the feed into the session to be used in your chain. From the docs:

Every time a virtual user reaches this step, it will pop a record out of the Feeder, which will be injected into the user’s Session, resulting in a new Session instance.

These feed( feeder ) calls can be chained alongside exec(), pause(), each(), etc. This means you can pull the next value from any feed within a loop, for example. This placement of feed( feeder ) calls is harder to find in the docs and was the source of my misunderstanding.

The below code illustrates the use of loops combined with feeds (NOT a full or real test scenario, just meant to illustrate how two feeders can be used in combination):

val usersFeeder = csv( "users.csv" )
val pagesFeeder = csv( "pages.csv" ).random

// ...

feed(userFeeder) // puts the next user from the feed in session
  .exec(
    http("Login page")
      .get("/login")
  )
  .exec(
    http( "Do login" )
      .post( "/loginaction" )
      .formParam("loginid","${loginid}") // loginid from userfeeder
      .formParam("password", "${password}") // password from userfeeder
  )
  .repeat(5) {
    feed(pagesFeeder) // puts the next page from pagesFeeder into session
      .exec(
        http("Visit random page")
          .get("${pageuri}") // pageUrifrom pagesFeeder
      )

  }
// ...