# \[Gatling2\] adding random int as query param
**URL:** https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649
**Category:** Gatling (Open-Source)
**Created:** [November 5, 2013, 10:34am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649 "2013-11-05T10:34:03Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Uladzimir\_Kazimirchy](https://community.gatling.io/u/Uladzimir_Kazimirchy)
#### Post date: [November 5, 2013, 10:34am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/1 "2013-11-05T10:34:03Z")
Hi!
I need to avoid server request caching so i decided to add a random int as query param to urls.
I’m trying to add additional parameter via .queryParam(“param”, “value”) and use
_ThreadLocalRandom.current.nextInt(1000)_ as a random number generator. The problem is –
when I add .toString and pass this value to .queryParam I get an error:
type mismatch;
found : () =\> String
required: io.gatling.core.session.Session =\> io.gatling.core.validation.Validation[String]
13:25:58.444 [ERROR] i.g.a.ZincCompiler$ - .queryParam(“testParam”, ThreadLocalRandom.current.nextInt(1000).toString)
What am I doing wrong…?
Thanks.
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### Author:  [@Excilys](https://community.gatling.io/u/Excilys)
#### Post date: [November 5, 2013, 10:54am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/2 "2013-11-05T10:54:49Z")
Hi,
This indeed fails to compile with 2M3a but compiles fine with master, not sure why…
Anyway, this won’t work as you expect because you’re passing a value, not a function, ie it will be only evaluated once, when the scenario is built, not every time a request is built and sent.
long form: .queryParam(“testParam”, (session: Session) =\>ThreadLocalRandom.current.nextInt(1000).toString)
can omit session type as the compiler can infer it: .queryParam(“testParam”, session =\>ThreadLocalRandom.current.nextInt(1000).toString)
session is not used here anyway: .queryParam(“testParam”, \_ =\>ThreadLocalRandom.current.nextInt(1000).toString)
Cheers,
Stéphane
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### Author:  [@Uladzimir\_Kazimirchy](https://community.gatling.io/u/Uladzimir_Kazimirchy)
#### Post date: [November 5, 2013, 11:12am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/3 "2013-11-05T11:12:12Z")
Stéphane,
so I need something like this:
val httpProtocol = http.baseURL(“[http://some.url.com](http://some.url.com)”)
def getRand(i: Int) : String = ThreadLocalRandom.current.nextInt(i).toString
val scn = scenario(“Load test”)
.feed(csv(“test\_data.csv”).random)
.exec(http(“srvc\_call”).get("${url}")
.queryParam(“testParam”, getRand(1000))
.check(status.is(200))
)
Right?
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### Author:  [@Excilys](https://community.gatling.io/u/Excilys)
#### Post date: [November 5, 2013, 11:13am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/4 "2013-11-05T11:13:57Z")
Nope, getRand(1000) will still be evaluated once.
\_ =\> getRand(1000)
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### Author:  [@Uladzimir\_Kazimirchy](https://community.gatling.io/u/Uladzimir_Kazimirchy)
#### Post date: [November 5, 2013, 11:17am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/5 "2013-11-05T11:17:13Z")
and now I get ClassNotFoundException
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at scala\_maven\_executions.MainHelper.runMain(MainHelper.java:164)
at scala\_maven\_executions.MainWithArgsInFile.main(MainWithArgsInFile.java:26)
Caused by: java.lang.ClassNotFoundException: performance.img\_srvc.Img\_perftest.scala
at scala.tools.nsc.interpreter.AbstractFileClassLoader.findClass(AbstractFileClassLoader.scala:69)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at io.gatling.app.SimulationClassLoader$$anonfun$simulationClasses$1.apply(SimulationClassLoader.scala:56)
at io.gatling.app.SimulationClassLoader$$anonfun$simulationClasses$1.apply(SimulationClassLoader.scala:55)
at scala.Option.map(Option.scala:145)
at io.gatling.app.SimulationClassLoader.simulationClasses(SimulationClassLoader.scala:55)
at io.gatling.app.Gatling.start(Gatling.scala:174)
at io.gatling.app.Gatling$.fromMap(Gatling.scala:59)
at io.gatling.app.Gatling$.runGatling(Gatling.scala:80)
at io.gatling.app.Gatling$.main(Gatling.scala:54)
at io.gatling.app.Gatling.main(Gatling.scala)
That drives me crazy 🙂
What could be the reason?
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### Author:  [@Excilys](https://community.gatling.io/u/Excilys)
#### Post date: [November 5, 2013, 11:22am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/6 "2013-11-05T11:22:47Z")
o\_O
Is performance.img\_srvc the expected package name and Img\_perftest the expected Simulation class name?
Is performance/img\_srvc a valid folder hierarchy?
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### Author:  [@Uladzimir\_Kazimirchy](https://community.gatling.io/u/Uladzimir_Kazimirchy)
#### Post date: [November 5, 2013, 11:29am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/7 "2013-11-05T11:29:57Z")
Yes. I guess if it was wrong then I should get the same error earlier(instead of Type Mismatch one).
But when I corrected the error with types in .queryParam - I got this one. That’s strange…
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### Author:  [@Excilys](https://community.gatling.io/u/Excilys)
#### Post date: [November 5, 2013, 11:35am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/8 "2013-11-05T11:35:34Z")
At this point, I can’t help you find out what’s wrong with getting my hands on your files.
Can you share?
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### Author:  [@Uladzimir\_Kazimirchy](https://community.gatling.io/u/Uladzimir_Kazimirchy)
#### Post date: [November 5, 2013, 11:35am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/9 "2013-11-05T11:35:55Z")
My bad, sorry. I added .scala extension to class name when running by maven.
So it was looking for scala class 🙂
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### Author:  [@Excilys](https://community.gatling.io/u/Excilys)
#### Post date: [November 5, 2013, 11:37am UTC](https://community.gatling.io/t/gatling2-adding-random-int-as-query-param/649/10 "2013-11-05T11:37:58Z")
Ahhhhhhh 🙂