Groovy ALM HpQC - Groovy exception - How to fill ST_ACTUAL design step field - groovy

Question

I am trying to update HpQC result from SOAP-UI groovy script
but I'm currently unable to modify ST_ACTUAL field of design step,
only to read the current value.
each try conduct to groovy exception ("designStep.item(c).Field(ST_ACTUAL)" is a method call expression, but it should be a variable expression" for exemple)
For my try, I have two steps under a test. Could you help to solve my issue and tell me where I'm wrong? In advance, thanks a lot for your help and answers.
//############# Connexion a HpQC ###############
def tdc = new ActiveXObject ('TDApiOle80.TDConnection')
tdc.InitConnectionEx(addresse_qc)
tdc.Login(login_qc, psw_qc)
tdc.Connect(domain_qc, project_qc)
log.info "*** connected to QC ***"
//Catch the testSet campain in the Test Lab
oTestSetFolder = tdc.TestSetTreeManager.NodeByPath(chemin_dans_qc)
list_TestSetList = oTestSetFolder.FindTestSets(testSet_name_qc)
oTestSet = list_TestSetList.Item(1)
//catch the test list in the Test Lab
oTestSetFactory = oTestSet.TSTestFactory
testList = oTestSetFactory.NewList("")
def nb_test = testList.Count()
// select first test (item(1) -- Current status test Run - should be "No Run"
selected_test = testList.Item(1)
log.info("OnGoing test : " + "ID="+ selected_test.ID +" - "+ selected_test.name + " - status= "+selected_test.Status)
// Create a new Test Run and modified final status for try
OnGoing_RunTest= selected_test.RunFactory.AddItem('Comment 1')
OnGoing_RunTest.Status = 'Blocked'
def b=OnGoing_RunTest.ID
OnGoing_RunTest.Post()
OnGoing_RunTest.CopyDesignSteps()
OnGoing_RunTest.Post()
Stepslist_of_OnGoing_RunTest = OnGoing_RunTest.StepFactory.NewList("")
//def nbsteps= Stepslist_of_OnGoing_RunTest.count()
def c=1
for(designStep in Stepslist_of_OnGoing_RunTest)
{
// lecture designStep
def a=designStep.ID
// checking previous information : ok
//log.info("DesignStep_ID="+designStep.ID)
//log.info("ST_STEP_NAME = "+ designStep.field("ST_STEP_NAME"))
//log.info("ST_STATUS = "+ designStep.field("ST_STATUS"))
//log.info("ST_DESCRIPTION = "+ designStep.field("ST_DESCRIPTION"))
//log.info("ST_EXPECTED = "+ designStep.field("ST_EXPECTED"))
// updating Status and ST_ACTUAL field
designStep.Status="Not Completed" // : OK
// Updating ST_ACTUAL field
// designStep.Field("ST_ACTUAL")="123" // => KO
//designStep.item(c).Field("ST_ACTUAL")="123" // ==> KO
// designStep.item(designStep.ID).Field("ST_ACTUAL")="123" // ==> KO
// designStep.item(designStep.ID).Field("ST_ACTUAL")="123" // ==> KO
c++
log.info("ST_ACTUAL = "+ designStep.field("ST_ACTUAL"))
designStep.post()
}
//Updating Run QC
selected_test.Post()
log.info("*** ---- END Test --- ***")
//######### déconnection de QC ############
tdc.Disconnect()
//On écrit dans le log
log.info("### -- QC disconnect -- ### -- END -- ###")

Answer 1

I never tried in Groovy but in Ruby I had to use something like this (untested for this exemplary code):
designStep["ST_ACTUAL"]="123"