Hi guys, I'm trying to create an expression to retrieve group id

Try the below code.
apply(
fn!getgroupbyname(groupName:_),
{ri!arrayofgroupNames}
)

Hi fredericom,
try this
apply(getgroupbyname(groupName:_),{"Group1","Group2"})

@rahulg262 and @sandeepd thanks for your suggestions. I already tried and it worked :)

One more question: can you explain to me why you used this format "groupName:_" for function parameter

Try apply(fn!getgroupbyname,cons!allGroupNames)

The constant could be replaced by any variable such as a Process Variable or Rule Input which contains all your group names.

This is called "Partial Evaluation" of rules/functions.. This is useful when you don't want to supply every rule parameter at design time OR when the rule should iterate over multiple arguments. An "_(underscore)" placed in the list of parameters for a rule is called a placeholder for that parameter and its not necessary when the rule has only one parameter. In case it has multiple parameters then you can specify values for some parameters and while leaving others using '_'. Values for these placeholder parameters are provided at run time from with in the list of values you specify in an apply() function. See the following documentation.

forum.appian.com/.../Expressions.html

Thank you guys :)