how can i put in a check what it will check on the stock room for availability at reassigning sctask

[chercm]

i have a catalog form created. 

1. how can i make it automatic populating the stock room field based on the configuration of the stock room ?

2. how can i put in a check for stock availability in that particular stock room of the item in the variable field before re-assigning the ticket ? 

i tried to use this but stockroom field of the form is still blank 

(function executeRule(current, previous /*null when async*/) {

// Check if Assignment Group is set

if (current.assignment_group.getDisplayValue() != '') {

// Query the Stockroom based on Assignment Group

var stockroomGR = new GlideRecord('alm_stockroom');

stockroomGR.addQuery('assignment_group', current.assignment_group);

stockroomGR.query();

// If a stockroom is found, set the Stockroom field on the catalog form

if (stockroomGR.next()) {

current.stockroom = stockroomGR.getValue('name');

}

}

})(current, previous);