Returning new session after a non-session setter operation

Gatling (Open-Source)
1

I never understood the following piece of documentation

.exec(session => {
  // print the Session for debugging, don't do that on real Simulations
  println(session)
  session
})
.exec(session =>
  // session.setAttribute returns the new Session, and Scala automatically returns the last assignment
  // braces are omitted as there's only one instruction
  session.setAttribute("foo", "bar")
)

in

http://gatling.io/docs/1.5.6/user_documentation/reference/session.html

Why is there a “session” after the print statement ? does it return the old session or a new session (in case it is altered just before the print statement ).

If I remove the session after the print statement it says type mismatch error.

2

Yes, the first example returns the original Session object. If you were to change it before the print, like this:

.exec(session => {

  session.setAttribute("foo", "bar")
  // print the Session for debugging, don't do that on real Simulations
  println(session)
  session
})



It would return the original object, and the changes would be lost, because set() returns a new Session object. If you want to keep the change, you have to do this:



.exec(session => {

  var newSession = session.setAttribute("foo", "bar")
  // print the Session for debugging, don't do that on real Simulations
  println(newSession)
  newSession
})



You can't remove it because then the session function is missing a return matching the return type.
3

Thanks Michelle

Now I got it. My problem is that the operation before the print statement is an exec(http(“XXXXX”) , had that been a session setter I could have made sure its the last line of the block. Can I assign the output of exec(http(“XXXXX”) , to a session object and return in the last line ?

4

I’m not sure you even can do that inside a session function. Is there any reason your request can’t be before the session function?

I.e. if you’re trying to do this:

.exec(session => {

  var newSession = exec(http("..."))
  // print the Session for debugging, don't do that on real Simulations
  println(newSession)
  newSession
})

Do this instead:

exec(http("..."))

.exec(session => {
  // print the Session for debugging, don't do that on real Simulations
  println(session)
  session
})
5

Michelle is right, you can’t do that in a session function, as executing a http request does not return a new session.
Operations altering the session from a http request (e.g. saving the result of a check using saveAs) are handled internally.

But nothing prevents you to do as Michelle suggested : execute the request first and then use a exec taking a session function to print the session’s content if you like.

6

Yes, I did change my code so that only the session mutation part is in the session function , rest of the code block is outside.

We can close the thread.
Thanks a ton.