This has been in my queue for a bit to figure out.

I tried this again with a fresh scoped application and this is not currently possible to do entirely within a scope.  At some point you need to either shim in access to a script include or create something in global.

I'll walk through the working solution for whatever poor soul happens across this.

1. Create a scoped application.
2. Create a table called "Content"
3. Add two fields, "Title" (string), "Stage" (choice)
4. Give Stage a few choices.
5. We're done in the scope.
6. Switch to global
7. Copy the rule "metric events", and point it to your scoped table.
8. That's it.

Now I feel like I need to argue with myself.

"Come on, it can't be impossible."

Okay, lets walk through the last 3 hours of my life.

The business rule

I created a scope, table, copied the business rule, "metrics events".

Created a Fix Script to test running this quickly.

GlideScriptRecordUtil is not available in scopes.

So this was used to get the fields that changed.  Okay some work and I got a working scoped version here.

function getChangedFieldNames(gr) {
  var result = [];
  var elements = gr.getElements();
  var size = elements.length;
  for (var i = 0; i < size; i++) {
    var ge = elements[i];
    if (ge.changes()) {
      result.push(ge.getName());
    }
  }
  return result;
}

Once that's added to the business rule we can call it instead of GlideScriptRecordUtil.

//var gru = new GlideScriptRecordUtil.get(current);
//var fieldsChanged = gru.getChangedFieldNames();
var fieldsChanged = getChangedFieldNames(current);

addActiveQuery is not available in scopes.

Okay updated the `getDefinitions` function to use gr.addQuery('active', 'true');

GlideDBObjectManager.getTables() is not available in scope.

There's a replacement

var tables = new GlideTableHierarchy(table);

Then when you would have called tables before you call tables.getTables();

metric.update is not available or found for scope.

So either I don't know how to give permission to generate a global event OR I need to create a scoped version of the event and trigger it.

Created a the scoped version of the event and updated the gs.eventQueue line to

gs.eventQueue(
  'x_8821_testmetric.metric.update', 
  current, 
  fields, 
  current.sys_mod_count, 
  'metric_update'
);

At this point you have a working rule that should work if you can get the event to process.  Since this is a different script I'm breaking this up here.

The Script Action

Created a copy of the script action that processes metric.update.

Because it's async, created another fix script and emulated running the code there.

GlideDBObjectManager.getTables not available in scope

We solved this before, so just solved that the same way.  Well nearly, I passed in a table since I was having some other problem with my fix script.

//var tables = GlideDBObjectManager.getTables(current.getTableName());
var tables = new GlideTableHierarchy(table);
gr.addQuery('table', tables.getTables());

Nail in the coffin is next.

GlideRecordRollback not available in scope

I don't see a way around this unless someone reverse engineers how the toVersion function works.  I looked and didn't find anything.

If anyone else wants to try this please have it and comment on the thread here so I can follow along with my ????.

References

Original Post

Docs on Metric Definitions that say create a rule

Final Business Rule in global.

(function executeRule(current, previous /*null when async*/) {
  queueMetricUpdate();
  function queueMetricUpdate() {    
	var gru =  new GlideScriptRecordUtil.get(current);
	var fieldsChanged = gru.getChangedFieldNames();
	var gr = getDefinitions(fieldsChanged);
	fields = '';
	while (gr.next()){
      fields += gr.field + ',';
    }
	if (fields.length > 0) {
      fields = '[' + fields.substring(0, fields.length - 1) + ']';
      gs.eventQueue('metric.update', 
                    current, 
                    fields, 
                    current.sys_mod_count, 
                    'metric_update'
                   );
	}
}
  function getDefinitions(fields) {
	var gr = new GlideAggregate('metric_definition');
	gr.addActiveQuery();
	var tables = GlideDBObjectManager.getTables(current.getTableName());
	gr.addQuery('table', tables);
	gr.addQuery('field', fields);
	gr.groupBy('field');
	gr.query();
	return gr;
  }
})(current, previous);