Dot walking through multiple tables in client script

[Kyle Wiley]

I am trying to dot walk through multiple tables in an onChange client script on the Incident table.  When the Caller field on the INC form changes, I want to reference the sys_user table to see what department the Caller is in.  The field that I am trying to use on the Department table is u_department_group.

function onChange(control, oldValue, newValue, isLoading, isTemplate) {

   if (isLoading || newValue === '') {

      return;

   }

var caller = g_form.getReference('caller_id');

var dept = g_form.getReference('caller_id').department;

   if (newValue) {

  confirm(caller.name);

  confirm(dept);

   }

}

caller.name prints out the user's full name as it displays in the sys_user table but when I try to print out dept, the only value I get is the sys_id.  I cannot get the department name to display or any other field on the Department table to display anything.

Is this possible in a client script?  

[drjohnchun]

There are limitations with dot-walking on the client side.

[Goran WitchDoc]

I would recommend making a glide ajax call instead since the getReference isn't something that is recommend and best practice. It may be used in simple cases. But in this one, I wouldn't use it.

Let me know if you need help with the glideajax stuff.

//Göran

[drjohnchun]

Another option is to use .getReference() with a callback function, making it asynchronous like GlideAjax.

[Kyle Wiley]

I wouldn't mind to write it as a GlideAjax but I don't have much experience writing scripts in that format.  

[drjohnchun]

One way to improve .getReference() is to make it asynchronous by providing a callback function as the second parameter as below, modified from the "answer":

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
   if (isLoading || newValue === '') {
       return;
   }

   var caller = g_form.getReference('caller_id', getDept);

   function getDept(caller) {
       var dept = caller.department;
       if (dept) {
           var grDept = new GlideRecord('cmn_department');
           if (grDept.get(dept)) {
               confirm(caller.name + ' works at ' + grDept.u_department_group);
           }
       }
   }
}

Here, the getDept() function gets executed only when the server returns the caller reference; in the meantime, the browser continues doing other things. However, this will make yet another subsequent call to the server inside the getDept() function to get cmn_department.u_department_group via GlideRecord. All these can be done by making a single GlideAjax call to the server with some added scripts both on the client and server side.

Please see Client Script Best Practices - ServiceNow Wiki: Minimize Server Lookups for more details.