grantDeleteProcess.js

import("system.result");
import("Sql_lib");
import("system.vars");

//Don't allow deletion if the district is a superordinate district
var districtId = vars.get("$field.DISTRICTID");
var count = newSelect("COUNT(*)")
                    .from("DISTRICT")
                    .where("DISTRICT.PARENTDISTRICT_DISTRICTID", districtId);   
                    
var canDelete = new HasLinkedObjectTester()
    .andNoEntityRows("Document_entity", "Documents", {AssignmentTable_param : "DISTRICT", AssignmentRowId_param : districtId}) //Documents
    .andSqlYieldsZero(count)
    .validate();

result.string(canDelete);