Need to populate group and user names in dropdown as a list

Please try below piece of code , hope it helps

a!localVariables(
/*Constant which holds the array of groups*/
local!groupList: cons!SRO_GROUPS,
local!selectedGroup,
local!selectedUser,
local!userList: a!refreshVariable(
value: getmemberuserspaging(
groupId: group(local!selectedGroup, "id"),
startIndex: 0,
batchSize: - 1
),
refreshOnReferencedVarChange: true
),
{
a!dropdownField(
label: "Select Group",
choiceLabels: a!forEach(
local!groupList,
rule!APN_displayGroupOrUsername(fv!item)
),
choiceValues: local!groupList,
value: local!selectedGroup,
placeholder: "Select a group",
saveInto: local!selectedGroup
),
a!dropdownField(
label: "Select Users",
choiceValues: local!userList,
choiceLabels: a!forEach(
local!userList,
rule!APN_displayUser(fv!item)
),
value: local!selectedUser,
saveInto: local!selectedUser,
placeHolder: "Select User"
)
}
)

Thanks a lot, Above code had got groups and users in Dropdown. But getting Group id in dropdown and user email id in dropdown. How to get Group name instead group id and username and last name instead emailid?

a!paragraphField(
value:rule!APN_displayGroupOrUsername(local!selectedUser)&" "&rule!APN_displayGroupOrUsername(local!selectedGroup)
),

use this function rule!APN_displayGroupOrUsername on the selectedUser and selectedGroup local variables

what is rule expression syntax - rule!APN_displayGroupOrUsername()

- rule!APN_displayGroupOrUsername()

For user i used below

/*getusersby("dshinde@firstam.com",3,1)*/
fn!concat(
fn!user(ri!email,"firstName"),
" ",
fn!user(ri!email_id,"lastName")
)

For user i used below

/*getusersby("dshinde@firstam.com",3,1)*/
fn!concat(
fn!user(ri!email,"firstName"),
" ",
fn!user(ri!email_id,"lastName")
)