User-ID and Custom Dimensions?

[grimmwerks]

They seem similar from a GA standpoint; but the attribution of User-ID was added to track users across devices. Google says to implement by

ga(‘set’, ‘&uid’, {{USER_ID}}); // Set the user ID using signed-in user_id.

Is this the same as setting custom dimensions and metrics, and how do we do that with rack-google-analytics?

In some cases, you might want to send a custom dimension or metric with all the hits on a given page (or for the lifetime of the tracker object). In this case, you can set the custom dimension or metrics using the set command:

ga('set', 'dimension5', 'custom data');
To set values for both a dimension and metric, you can use:

ga('set', {
'dimension5': 'custom dimension data',
'metric5': 'custom metric data'
});
Read the Custom Dimensions and Metrics Section in the Field Reference document for the specific format of how to send this data.

[grimmwerks]

...and with the user_D send - this seems to be something done on everypage; unsure if there's a way to send it into the gem so that it too sends along on page views automatically?