Gatling 2 - need example of handling dynamic values in json request files using both templates and objects

Gatling (Open-Source)
1

Hi,

I am using Gatling 2

I am working on the task of handling dynamic value in json request file body - as per HTTP template documentation for Gatling1.

json request is recorded in a text files e.g. “request_4.txt”

This is what I have done to change value dynamically using templates (.ssp):

  1. renamed request_4.txt to request_4.ssp (it is under /user-files/request-bodies)
  2. modified the content of request_4.ssp as following:

[
{
“id” : 13183,
“time” : “<%= timevalue %>”,
“login” : 2986,
“objects” : [
{
“id” : -23,
//…
“number” : 1

}
]
}
]

  1. changed code in recorded simulation:

val scn = scenario(“Create Leg”)

//…
.exec(http(“request_4”)

.post("""/api/sync/137/13183""")
.headers(headers_1)
.fileBody(“request_4”, Map(“timevalue” → “1374062413”))
// .body(RawFileBody(“request_4.txt”)) // this is what has been recorded

I get syntax error - it does not like fileBody - that is expected. Having read the Gatling 2 update page I figured out there were changes in the API, I fiddled a little bit but no luck.

It would be great if you could provide me and community with an example of solving this task in gatling 2:

  1. using templates
  2. using objects (as mentioned on the update page) - example at the bottom of this section does not provide enough information to get me started.

Many thanks in advance,
Natalie

2
  • Template:

Probably the easiest solution for non Scala devs.

request_4.txt:

[
{
“id” : 13183,
“time” : “${timevalue}”, // use regular Gatling EL
“login” : 2986,
“objects” : [
{
“id” : -23,
//…
“number” : 1

}
]
}
]

val scn = scenario(“Create Leg”)
//…
.exec(http(“request_4”)

.post("""/api/sync/137/13183""")
.headers(headers_1)
.body(ELFileBody(“request_4.txt”)) // assume that the Session contains a “timevalue” attribute (from feeder, check.saveAs, or else)

  • Programmatically

You have to be familiar with for comprehension and string interpolation in Scala.

val template: Expression[String] = (session: Session) =>
for {
timevalue = session(“timevalue”).validate[String]
} yield s"""[
{
“id” : 13183,
“time” : “$timevalue”, // string interpolation
“login” : 2986,
“objects” : [
{
“id” : -23,
//…
“number” : 1

}
]
}
]"""

val scn = scenario(“Create Leg”)
//…
.exec(http(“request_4”)

.post("""/api/sync/137/13183""")
.headers(headers_1)
.body(StringFileBody(template))

Get it?

Stéphane

3

Thanks Stéphane!

I see you have dropped SSP support so EL is the way to go for me - I want to make it work first than experiment with the string interpolation option later.

The simulation runs fine but cannot find timevalue

“01:19:55.121 [ERROR] i.g.h.a.HttpRequestAction - No attribute named ‘timevalue’ is defined”

I calculate timevalue programatically and need to set this as an attribute to a session I guess.

However this does not work:

val scn = scenario(“Create Leg”)
//…
.exec(session =>
session.set(“timevalue”, “1374062413”))

.exec(http(“request_4”)

.post("""/api/sync/137/13183""")
.headers(headers_1)
.body(ELFileBody(“request_4.txt”)) // assume that the Session contains a “timevalue” attribute (from feeder, check.saveAs, or else)

Thanks,

4

Looks good to me.
Could you paste your template file, please?

5

Hi Stéphane,

actually this code as specified above works now.
(I had to tidy up some other bits and pieces in simulation class).

Thanks so much for your help - it is invaluable.

I will try the other solution in a short while.

—Natalie

6

Great!