Difference between val and def for scenario definition

Gatling (Open-Source)
1

Hi,

I am defining a Gatling scenario and I would like to separate the http calls from the scenario. Instead of coding the whole definition in my scenario, I want to create a package containing all my http calls…
Instead of :
val myScenario = scenario(“Test”)
.exec(
http(“transaction 1”).post("/bla/bla").headers(…).formParam(…)…
)
.exec(
http(“transaction 2”).post("/bla/bla").headers(…).formParam(…)…
)
etc…
I want to define 1 object per http call and use them as I want in my future scenarios, like this:
val myScenario = scenario(“Test”)
.exec(myTransaction1) //defined in another object
.exec(myTransaction2) // same

The question is: what is the best way to declare my object containing the http call ?
object GetIAMToken {
def myTransaction1: HttpRequestBuilder = http(“transaction 1”).post…
}

OR

object GetIAMToken {
val myTransaction1: HttpRequestBuilder = http(“transaction 1”).post…
}

I’m quite new to Scala and I’ve read that val is evaluated when defined, and def is evaluated on call.
Also, I’ve seen this example on internet (for use of val):
Capture.PNG

Does val have the same behaviour if I define an HTTP call using it ? For example if I want to extract an ID in the json response from the server, randomly, I don’t want it to be always the same.

Thanks for your help !

Terry

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2

Hi,

I can understand your confusion, more with the sample you provided.

The sample really defines a function with a return value computed only once.

But as suggested by the type: HttpRequestBuilder (a builder, not a final request), if the code does not depend on external values, you should be good to create a val.
More, exec accepts values as parameters (not functions), it can be a clue that you can use val safely.

But as you said, this is a question about scala itself and not specific to gatling.
Any tutorial or course on scala will you explain it better than I can.

Cheers!

Capture.PNG

3

Again thank you for your answer !

Terry