Gatling payload generation using multiple rows from a Feeder file

gargantuan_payload.scala

package performance.simulations.scenarios

import io.gatling.core.Predef._
import io.gatling.http.Predef._
import performance.simulations.lib.JenkinsParam._
import performance.simulations.lib.RandomFeeder._
import performance.simulations.lib.SharedHeaders._

/**
 * Created by nwhit8 on 9/21/15.
 */
class CommandService extends Simulation {
  // feeder file with ReceiverId column 
  val receiverFeeder = csv("temp_pal_receivers.csv").random

// list builder
  def buildListFromSession( session: Session ) : String= {
    // get all keys that match the pattern for this variable
  val kitchenSink = session.attributes.toMap
    val filtered = kitchenSink.filter(( x) => x._1 startsWith("ReceiverId"))
//    prefix="   delimiter=","   suffix="
val myUsers = filtered.values.mkString("\"", "\",\"", "\"")

myUsers
  }

// generates JSON payload 
  def genGargantuanPayload(payloadType: String, recipientApp: String, userIds: String ): String = {

    val gargantuan = """
     {
"payload_type": "category:${Type3}",
"locale_language": "en",
"locale_country": "US",
"recipients": [
${MyList}
] ,
"content": {
  "template": "design8"
}
}

    """
    gargantuan
  }

// request that uses the payload and userId list
  val scnPostHugePayloads = scenario("POST-HUGE-PAYLOADS")
  /// grab 1000 rows from feeder file
      .feed( receiverFeeder,1000 )
      .feed( timestampXB3Feeder )
      
      // set up session attributes that will be used to build the payload
                                .exec( session => {
    session.set("LaunchType", "foo:promo:Holiday")
    .set("RecipientApp", "com.foursquare")
    .set( "MyList", buildListFromSession( session))
  })
    
    // adjust baseURL and resource path to match application being tested
                             .exec({
    val resource = baseURL + "/resource/path/requests"
    
    http("POST-HUGE-PAYLOADS")
   
    .post(resource)
    .body( StringBody(
     genCampaignPayload( "${LaunchType}", "${RecipientApp}", "${MyList}"))).asJSON

    .check( status.is(202))
  })

}