Unable to create different values in map within a repeat

[Robert Hafner]

I'm new to gatling/scala and am running into an issue in which the following repeat section is not creating different values for the definitionProperties map in each iteration. I'm looking for an explanation as to why it doesn't work as well as an alternative way to implement this logic.

.repeat(10) {
  val performanceModel : String = DefinitionUtil.getDefinitionAsString("Performance2")
  val performanceDefinitionId = "WF7FF447E1-AAA5-4ECF-850F-99702FFE3042"

  val headers = Map(
    "Authorization" -> ("${tokenType} ${accessToken}"),
    "Content-Type" -> "application/vnd.workflow.definition+json",
    "Accept" -> "application/vnd.workflow.definition.summary+json"
  )

  var definitionId = "WF".concat(java.util.UUID.randomUUID().toString)
  var name = definitionId
  var comment = "Definition ".concat(definitionId)
  var model = performanceModel.replace(performanceDefinitionId, definitionId).replace("Performance2", name)

  var definitionProperties = Map(
    "id" -> definitionId,
    "name" -> name,
    "comment" -> comment,
    "clientRegistrationId" -> clientRegistrationId,
    "model" -> model
  )

  exec(WorkflowAction.createDefinition(definitionProperties))
}

thanks,

Rob

[Stephan D.]

The variables are only evaluated once at the time the scenario is built. 

I think you have to set the values within a session.

[Robert Hafner]

Thanks for the response Stephan! I have another method (shown below) which is called with different values (for the name parameter) in my scenario and the variables are evaluated for each call. Any idea why these variables are evaluated each time based on the name parameter and the other variables are only evaluated once when the scenario is built.

def createTag(name : String) = {
  var tagProperties: Map[String, String] = Map("name" -> name)
  val body = JsonUtil.mapToJsonString(tagProperties)

  val headers = Map(
    "Authorization" -> ("${tokenType} ${accessToken}"),

    "Content-Type" -> "application/vnd.workflow.tag+json",
    "Accept" -> "application/vnd.workflow.tag+json"
  )
  exec(http("Create Tag")
    .post("/workflow/tags")
    .headers(headers)
    .body(StringBody(body)).asJSON
    .check(status.in(201)))
}

 

[Stephan D.]

With the new method you are starting a new session every time you finished your "post", right? 

But with the first example you are looping within a session. To manipulate a running session you need to use the session api gatling provides. 

Maybe Stephane can verify this answer. I'm not 100% sure and pretty new to scala and gatling too ;)  

[Robert Hafner]

I'm creating my scenario using the following class. I'm not sure I understand where the session is being created. 

I believe the session is associated with each virtual user, however I'm not sure where the session begins/ends. Is the session not created until the duration block?

In the code below the call in the repeat block does not work, however, making multiple calls does. Not sure I understand why after re-reading the documentation.

class BasicWorkflowScenario(durationMinutes: Int, userFeeder: FeederBuilder[String]) extends
  ScenarioCreator {
...

  override def getScenario(): ScenarioBuilder = scenario(name)
      .exec(LoginAction.administratorLogin)
      .feed(userFeeder)
    .exec(LoginAction.switchToWorkflowAdmin)
    .exec(WorkflowAction.createTag("Tag1"))
    .exec(WorkflowAction.createTag("Tag2"))
    ...

    // This results in a http status of 409 b/c it uses the same UUID value for each iteration.
    .repeat(10) {

      exec(WorkflowAction.createDefinition("WF".concat(java.util.UUID.randomUUID().toString), clientRegistrationId))

    }

    // However, if I don't use repeat block, but rather make individual calls it produces unique values.

    exec(WorkflowAction.createDefinition("WF".concat(java.util.UUID.randomUUID().toString), clientRegistrationId))

    exec(WorkflowAction.createDefinition("WF".concat(java.util.UUID.randomUUID().toString), clientRegistrationId))

    ...

    .during(durationMinutes * 60) {
      // call other actions
      pause(1)
    }
  }

}

[Vu Nguyen]

Robert,

I think this thread provides you some guidance

https://groups.google.com/d/msg/gatling/Anl1Kuvbk0A/eWYlcbdNPIMJ

Vu

---

[Robert Hafner]

Thanks Vu. I updated the exec call to specify a session in an attempt to use a lambda. However, the code fails to compile with this change. Any idea what I'm doing wrong here?

07:25:27.269 [ERROR] i.g.c.ZincCompiler$ - C:\workspaces\viya\workflow-test-integration\src\test\scala\com\workflow\test\qa\perf\scenarios.scala:48: type mismatch;
 found   : io.gatling.core.structure.ChainBuilder
 required: io.gatling.commons.validation.Validation[io.gatling.core.session.Session]
07:25:27.269 [ERROR] i.g.c.ZincCompiler$ -       WorkflowAction.createDefinition(
07:25:27.270 [ERROR] i.g.c.ZincCompiler$ -                                      ^
07:25:27.275 [ERROR] i.g.c.ZincCompiler$ - one error found
07:25:27.276 [ERROR] i.g.c.ZincCompiler$ - Compilation crashed
sbt.compiler.CompileFailed: null
        at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:105)
        at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:47)
        at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:41)

...

For reference, here are the code changes I made.

BasicWorkflowScenario.scala:

scenario(name)

.exec( (session:Session) =>
  WorkflowAction.createDefinition(
    "WF".concat(java.util.UUID.randomUUID().toString()),
    clientRegistrationId,
    session
  )
)

WorkflowAction.scala:

def createDefinition(definitionId: String, clientRegistrationId : String, session : Session) = {

 ...

}

[Vu Nguyen]

I think you have two options:

 

Option #1

exec { session =>

  // function to do work

  WorkflowAction.createDefinition()

  // return the original session

  session

}

Option #2

exec { session =>

  // function to do work and return updated session

  WorkflowAction.createDefinition()

}

For more information, please check following topics in documentation

- Most Gatling DSL methods takes Expression[T] parameters, which is a type alias for Session => Validation[T]. They are allowed to return a Session instead of Validation[Session] because of an implicit conversion.

https://gatling.io/docs/current/session/expression_el/

- Gatling DSL exec can also be passed an Expression function.

https://gatling.io/docs/current/general/scenario/#exec

- Session is a virtual user’s state. Session instances are immutable!

https://gatling.io/docs/current/session/session_api/