# Looping for each char in string
**URL:** https://community.gatling.io/t/looping-for-each-char-in-string/6159
**Category:** Gatling (Open-Source)
**Created:** [June 22, 2021, 7:58am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159 "2021-06-22T07:58:18Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 22, 2021, 7:58am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/1 "2021-06-22T07:58:18Z")
Hi,
I am trying to send a request for each char in a String (in order to test an autocomplete service), but no request is sent:
var tmp = “”
val autocompleteMobile: ChainBuilder = exec(session =\> {
session(“text”).as[String].foreach { c =\>
tmp = tmp.concat(c.toString)
println("Mot: " + tmp)
exec(http(“Autocomplete MOBILE”)
.get(“my\_url/autocomplete?text=${tmp}”)
}
session
})
this ChainBuilder (autocompleteMobile) is called at a scenario level in another file like this:
val mobileAutocomplete: ScenarioBuilder = scenario(“Mobile autocomplete”)
.randomSwitch(
20d → feed(cl1).feed(search\_word).exec(autocompleteMobile),
20d → feed(cl2).feed(search\_word).exec(autocompleteMobile),
20d → feed(cl3).feed(search\_word).exec(autocompleteMobile),
20d → feed(cl4).feed(search\_word).exec(autocompleteMobile),
20d → feed(cl5).feed(search\_word).exec(autocompleteMobile)
)
When I execute this, I can see the expected behaviour but no request is sent:
**logs:**
Simulation simulations.Nominal started…
Mot: p
Mot: pa
Mot: par
Mot: parm
Mot: parme
Mot: parmes
Mot: parmesa
Mot: parmesan
[…] There were no requests sent during the simulation, reports won’t be generated
Any idea on what could have happenned?
Thank you in advance,
Terry
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---
### Author:  [@slandelle](https://community.gatling.io/u/slandelle)
#### Post date: [June 22, 2021, 8:06am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/2 "2021-06-22T08:06:30Z")
That can’t work.
[https://gatling.io/docs/gatling/reference/current/general/scenario/#exec](https://gatling.io/docs/gatling/reference/current/general/scenario/#exec)
Gatling DSL components are immutable `ActionBuilder`(s) that have to be chained altogether and are only built once on startup. The result is a workflow chain of `Action`(s). These builders don’t do anything by themselves, they don’t trigger any side effect, they are just definitions. As a result, creating such DSL components at runtime in functions is completely meaningless. If you want conditional paths in your execution flow, use the proper DSL components (`doIf`, `randomSwitch`, etc)
You have to use a proper Gatling DSL loop, not a scala loop inside a function.
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 22, 2021, 8:24am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/3 "2021-06-22T08:24:38Z")
Thank you Stéphane,
I try doing this in a Gatling’s foreach loop, but I can’t make it work because foreach expects scala.collection.immutable.Seq and I give him a String. I need to loop for each char. I am trying some other stuff.
@sujinsa, thank you too ! But this is not what I want to do.
For a given word (let’s say “banana”), I want to iterate over each char, and send multiple requests sequentially:
req1 with ‘b’
req2 with ‘ba’
req3 with ‘ban’
etc…
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 28, 2021, 7:43am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/4 "2021-06-28T07:43:25Z")
Hi,
I try to find a solution but I still can’t find one.
Is this possible ?
For now I simply try to print a session atrribute but this won’t work:
var tmp = “”
var list: Seq[String] = SeqString
val autocompleteMobile: ChainBuilder = exec { session =\>
session(“text”).as[String].foreach { c =\> //getting value from feeder
tmp = tmp.concat(c.toString)
list = list :+ tmp
}
println("out loop: " + list) // prints : “out loop: List(c, cr, cri, cris, crist, crista, cristal, cristali, cristalin, cristaline)”
session.set(“liste”, list)
println(“Liste:” + session(“liste”).validate[Seq[String]]) // prints nothing =\> Liste:Failure(No attribute named ‘liste’ is defined)
session
}.exec(…)
Any idea why I cannot find the session attribute liste ?
Thank you in advance
---
### Author:  [@slandelle](https://community.gatling.io/u/slandelle)
#### Post date: [June 28, 2021, 7:47am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/5 "2021-06-28T07:47:27Z")
[https://gatling.io/docs/gatling/reference/current/session/session\_api/#setting-attributes](https://gatling.io/docs/gatling/reference/current/session/session_api/#setting-attributes)
`Session` instances are immutable!
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 28, 2021, 8:02am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/6 "2021-06-28T08:02:58Z")
Sorry but I don’t understand why this does not work:
I try to do this:
var tmp = “”
var list: Seq[String] = SeqString // var is for mutable variables
val autocompleteMobile: ChainBuilder = exec { session =\>
session(“text”).as[String].foreach { c =\>
tmp = tmp.concat(c.toString)
list = list :+ tmp
}
val tmp\_list: Seq[String] = list // I create a tmp\_list with keyword ‘val’ which should be immutable
println("out loop: " + list)
session.set(“liste”, tmp\_list)
println(“Liste:” + session(“liste”).validate[Seq[String]])
session
}
This still does not work.
Liste:Failure(No attribute named ‘liste’ is defined)
Immutable means the value does not have to change after declaration right ? I just do session.set and session.get for printing. Can you please enlighten me ?
---
### Author:  [@sbrevet](https://community.gatling.io/u/sbrevet)
#### Post date: [June 28, 2021, 8:27am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/7 "2021-06-28T08:27:17Z")
Hi!
Take care that `session#set` returns a new instance. (as `session` is immutable, a new instance is returned instead).
```auto
exec { session =>
session("text").as[String].foreach { c =>
tmp = tmp.concat(c.toString)
list = list :+ tmp
}
val sessionWithList = session.set("liste", list) // <= new instance is created here!
println("Liste:" + sessionWithList("liste").validate[Seq[String]]) // <= use your new session
sessionWithList
}
```
Cheers!
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 28, 2021, 8:33am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/8 "2021-06-28T08:33:50Z")
That was it ! Thank you very much !
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 28, 2021, 9:37am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/9 "2021-06-28T09:37:01Z")
Hi Again,
Sorry for being unable to continue on my own, but I still cannot understand why it does not work. My need is to be able to iterate over a String, and send an HTTP request for each char in order to inject load to an autocomplete service:
var tmp = “”
var list: Seq[String] = SeqString
val autocompleteMobile: ChainBuilder = exec { session =\>
session(“text”).as[String].foreach { c =\>
tmp = tmp.concat(c.toString)
list = list :+ tmp
}
val newSession = session.set(“liste”, list)
println(“Liste:” + newSession(“liste”).as[Seq[String]]) // This works now =\> prints “Liste:List(l, la, lai, lait)”
newSession
}.exec( session =\> { //Here is the part where I cannot iterate over the List
println("List before foreach: " + session(“liste”).as[Seq[String]]) // Works fine too, prints “List before foreach: List(l, la, lai, lait)”
foreach(session(“liste”).as[Seq[String]], “text”) { // At this point, this does not work. =\> logs show “There were no requests sent during the simulation, reports won’t be generated”, which is normal. But nothing is printed before.
exec { session =\>
println(“Element: ${text}”) // I’m expecting this code to print each element of my List, but nothing is done. It’s like foreach does not iterate over it.
//future http call will be here
session
}
}
session
}
From the documentation: _sequenceName_ can be a sequence, an EL string pointing to a Seq[Any] Session attribute, or an Expression[Seq[Any]]
It seams that my session attribute is one of this.
Any help would be appreciated, thank you in advance.
Terry
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [June 29, 2021, 2:17pm UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/10 "2021-06-29T14:17:57Z")
Finally, I got it worked !
I post the solution here for those who will need it later on.
var tmp = “”
var list: Seq[String] = SeqString
val autocompleteMobile: ChainBuilder = exec { session =\>
session(“text”).as[String].foreach { c =\>
tmp = tmp.concat(c.toString)
list = list :+ tmp
}
val newSession = session.set(“liste”, list)
newSession
}.exec(
foreach("${liste}", “text”) {
exec(http(“Autocomplete MOBILE”)
.get("/my\_uri/${text}")
.header(“id”, “${catalog}”))
}
)
For exemple, with text=bed, this will send 3 requests:
1. /my\_uri/b
2. /my\_uri/be
3. /my\_uri/bed
---
### Author:  [@slandelle](https://community.gatling.io/u/slandelle)
#### Post date: [June 29, 2021, 2:22pm UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/11 "2021-06-29T14:22:24Z")
This is wrong.
You’ve defined tmp and list accumulators as global, hence shared amongst all virtual users.
This is going to break as soon as you’ll run more than 1 concurrent user.
Those accumulators should be unique per virtual user, hence stored inside their respective Session.
---
### Author:  [@Terry\_PITZ](https://community.gatling.io/u/Terry_PITZ)
#### Post date: [July 8, 2021, 10:12am UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/12 "2021-07-08T10:12:19Z")
Hi,
I think this might be a solution.
This works and the variables are saved as session attributes.
val autocompleteMobile: ChainBuilder = exec { session =\>
var tmpSession = session.set(“tmp”, “”).set(“list”, new ListBufferString)
session(“text”).as[String].foreach { c =\>
tmpSession = tmpSession.set(“tmp”, tmpSession(“tmp”).as[String].concat(c.toString))
tmpSession = tmpSession.set(“list”, tmpSession(“list”).as[ListBuffer[String]] += tmpSession(“tmp”).as[String])
}
val newSession = tmpSession.set(“liste”, tmpSession(“list”).as[ListBuffer[String]].toList)
newSession
}.exec(
foreach("${liste}", “text”) {
exec(http(“Autocomplete MOBILE”)
.get("/my\_uri/${text}")
.header(“id”, “${catalog}”))
}
)
NOTE:
I tried to replace these lines:
tmpSession = tmpSession.set(“tmp”, tmpSession(“tmp”).as[String].concat(c.toString))
tmpSession = tmpSession.set(“list”, tmpSession(“list”).as[ListBuffer[String]] += tmpSession(“tmp”).as[String])
with:
tmpSession = tmpSession.set(“tmp”, tmpSession(“tmp”).as[String].concat(c.toString)).set(“list”, tmpSession(“list”).as[ListBuffer[String]] += tmpSession(“tmp”).as[String])
But this does not work because tmpSession(“tmp”).as[String] has no value in the first loop.
Terry
---
### Author:  [@vu.nguyen](https://community.gatling.io/u/vu.nguyen)
#### Post date: [July 8, 2021, 7:56pm UTC](https://community.gatling.io/t/looping-for-each-char-in-string/6159/13 "2021-07-08T19:56:21Z")
Terry - see if this alternative works for you
val autocompleteMobile: ChainBuilder =
repeat(session =\> session(“text”).as[String].length, idx) {
exec(session =\>
session
.set(“input”, session(“text”).as[String].take(idx + 1))
)
.exec(
http(“Autocomplete MOBILE”)
.get("/my\_uri/${input}")
.header(“id”, “${catalog}”)
)
}