Post script function - multiple user picker custom field update

[IT Accounts]

Can't update multiple user picker custom field. 

Workflow transition's post function script:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.user.ApplicationUser;
def customFieldManager = ComponentAccessor.getCustomFieldManager()
def userManager = ComponentAccessor.getUserManager()
def Approvers = customFieldManager.getCustomFieldObjectByName("MultipleUserPicker")
List<applicationuser> newApprovers = []; 
ApplicationUser user = userManager.getUserByKey("user1"); 
newApprovers.add(user); 
user = userManager.getUserByKey("user2"); 
newApprovers.add(user);
issue.setCustomFieldValue(Approvers, newApprovers) 
issue.store();

This code gives no mistake in text editor, but when I performing transition it alerts:
It seems that you have tried to perform an illegal workflow operation.If you think this message is wrong, please contact your JIRA administrators.

I can't see logs. Does anybody know what is wrong? When I comment this line "issue.setCustomFieldValue(Approvers, newApprovers)" alert disappears.

Here on this page is example only for (single select) user picker. 
Thank You!

[adammarkham · Accepted solution]

You should use IssueService, which will do the reindexing for you. You should be able to replace your script with the one below:

import com.atlassian.jira.bc.issue.IssueService
import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.Issue

def customFieldManager = ComponentAccessor.getCustomFieldManager()
def issueService = ComponentAccessor.getComponent(IssueService)
def approvers = customFieldManager.getCustomFieldObjectByName("MultipleUserPicker")

def issue = issue as Issue

def user = ComponentAccessor.jiraAuthenticationContext.loggedInUser

def issueInputParameters = issueService.newIssueInputParameters()

// Adding the user names here
issueInputParameters.addCustomFieldValue(approvers.id, "user1", "user2")

def updateValidationResult = issueService.validateUpdate(user, issue.id, issueInputParameters)

if (updateValidationResult.isValid()) {
    issueService.update(user, updateValidationResult)
}

[IT Accounts]

I changed names of CustomField and users but it is not working.
This script generates no error, but field is empty. =((

[IT Accounts]

I think I know what happened, user must have a permission to edit? I'll check it...

[IT Accounts]

Is it possible to select another user, not current logged in? 
"Edit issue" is deprecated in our project, we are changing fields in transitions. Each field in its own transition (very strict).
 

[adammarkham]

Yes if the logged in user does not have issue edit permissions it can't be done. You should run it as a user with the correct permissions. You can get a user like so:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.user.util.UserManager

def userManager = ComponentAccessor.getComponent(UserManager)

def user = userManager.getUserByKey("userkey")

[Thomas Scheibelhofer]

Hi Adam,

I'm trying to do the same, but what i have is an array / list of users (= MemberUsernames) of which i do not know how many they will be.

Do you have a suggestion on how i could do that?

issueInputParameters.addCustomFieldValue(approvers.id, MemberUsernames)
 
def updateValidationResult = issueService.validateUpdate(currentReporterFull, issue.id, issueInputParameters)
 
if (updateValidationResult.isValid()) {
 issueService.update(currentReporterFull, updateValidationResult)
 }
 }
 

Thanks and best regards

Thomas

[IT Accounts]

I changed names of CustomField and users but it is not working.
This script generates no error, but field is empty.