Feeder reading multiple lines and foreach

Gatling (Open-Source)
1

Hello
I’m trying to run foreach on multiple records of feeder but foreach is not executing and no errors are shown

  scenario("my scenario")
    .feed(myFeeder, 5) //read 5 lines as array?
    .foreach("#{columnName}", "attrName") { session =>  //iterate over array
       println(session("attrName").as[String])
       session
  }

But if i change code to repeat, everything works (so file could be read)

scenario("my scenario")
  .repeat(5) { // read 5 lines one by one
    feed(myFeeder)
      .exec { session =>
         println(session("columnName").as[String])
         session
       }
  }

With gatling v 3.7.6 i can see keys in session like “columnName1”, “columnName2”, etc…
With gatling 3.9.1 or higher i can see key “columnName” but i don’t know its type so i cant do anything with it.

So what is the problem with combination like:

.feed(myFeeder, 5)
.foreach("#{columnName}", "attrName")

Different types, so foreach can’t iterate? or problem with feeder?
csv file has enough lines to read.

2

Here you have a little hints: :slight_smile:

3

This is not correct and has never been.
The second parameter list of foreach takes a chain, not a function.

.foreach("#{columnName}", "attrName") {
  exec { session =>
    println(session("attrName").as[String])
    session
  }
}
1 Like
4

Thank you for your reply, i’ve missed exec block when copied an example. My project compiles and runs but foreach don’t iterate over records of csv file.

5

Thank you. Example with UUID looks like what i want but with combination of gatling foreach.

Its not critical for me, i’ve used repeat instead.

I just want to know if i can use foreach for feeder records which were stored in array like this

6

Make sure to upgrade to the latest version (3.9.5 atm).
If you still experience an issue, please build a simple yet complete reproducer someone else can run on his side.

7

Here is an example

Found error in log:

Condition evaluation crashed with message ‘Can’t cast ‘[Ljava.lang.Object;@7cafc344’ of type class [Ljava.lang.Object; into interface scala.collection.immutable.Seq’, exiting loop

8

@oddfrost
below works for me without error :slight_smile:

I wondering how to cast in better way Object[] to ArrayList<String> - any suggestions @slandelle ? :smirk:

PR with Solution: Case0023foreachFromUUIDfeederFiveRecordsAtTheSameTimeSimulation by gemiusz · Pull Request #18 · gemiusz/gatling-examples-maven-java · GitHub
Any comments and sugestions are welcome :hearts:

Direct Link to Simulation code:

9

Yes, but putting objects from object array to ArrayList looks like a workaround. When working with api (gatling) expecting things to work without this step.
Like reading lines and storing them directly in Seq or ArrayList not in Object

10

As I see in Gatling source code (gatling/ForEach.java at main · gatling/gatling · GitHub) there is foreach in almost all methods so there must be List :slight_smile:

11

OK, this is actually a bug. Indeed, foreach doesn’t support arrays, only Seq and List. Investigating.

1 Like
12

Fixed: Core: Make foreach support arrays · Issue #4420 · gatling/gatling · GitHub

Should be released in 3.9.6 (no ETA at the moment).

1 Like
13

Hi @slandelle,
I have looked in Commit Make foreach support arrays, close #4420 · gatling/gatling@1ae49cb · GitHub
and I’m wondering why there aren’t any changes in JAVA code gatling/ForEach.java at main · gatling/gatling · GitHub
How your changes will appile to Java code if there are only List<?>, String, Function<Session, List<?>> types that can be used ?

14

Actually, I’m not satisfied with this solution.
I’m going with Core: Change multiple feed to generate either java.util.List or Scala Seq instead of Array (BREAKING CHANGE) · Issue #4423 · gatling/gatling · GitHub instead.

Cheers

1 Like
15

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