Navigate to history entry from ui action

slightly clunky way and perhaps not ideal, but it works

navigate to the history entry. the sysid corresponds to the id of the record changed

var grSHS=new GlideRecord('sys_history_set');//--record history

if (grSHS.get('id', '8cf2d354db733f403c304662159619a2')){

var grSHL=new GlideRecord('sys_history_line');//--history

grSHL.addQuery('field', 'assignment_group'); //--or whatever field has changed

grSHL.addQuery('set', grSHS.sys_id);

grSHL.addQuery('oldISNOTEMPTY^newISNOTEMPTY');

grSHL.orderBy('sys_created_on');

grSHL.query();

while(grSHL.next()){

  gs.print(grSHL.sys_id);

  gs.print(grSHL.old);

  gs.print(grSHL.old_value);

}

}

//--or in a script include:

call it this way:

gs.print(si.getAuditHistory_previousValue('8cf2d354db733f403c304662159619a2', 'assignment_group'));

getAuditHistory_previousValue: function(SYSID, FIELD_CHANGED){

                                //--purpose: retrieve the audit history from somewhere where previous. cannot be used, such as a UI Action

                                var sReturn='';

                                var grSHS=new GlideRecord('sys_history_set');//--record history

                                if (grSHS.get('id', SYSID)){ //--sys_id of the record that was changed

                                                var grSHL=new GlideRecord('sys_history_line');//--history

                                                grSHL.addQuery('field', FIELD_CHANGED);//--name of the field that was changed, e.g. 'assignment_group'

                                                grSHL.addQuery('set', grSHS.sys_id);

                                                grSHL.addQuery('oldISNOTEMPTY^newISNOTEMPTY');

                                                grSHL.orderByDesc('sys_created_on');

                                                grSHL.query();

                                                while(grSHL.next()){

                                                                //--return the sys id and display value, comma-separated

                                                                sReturn=+grSHL.old_value';'+grSHL.old;

                                                }

                                }

                                return sReturn;

                },