Laravel 5.5 / Scout：如何扩展Scout以使用连接？

Question

I am using Laravel/Scout/Elasticsearch via https://packagist.org/packages/babenkoivan/scout-elasticsearch-driver and I have this situation:

1. To search, I must use a model like this:

   $visits = Visit::search("canada")->with(['origin', 'profile', 'user'])->paginate(10);

It works very well.

1. As you can see, this model is related to three other tables: origins (that are countries), profile and users. The way the everything is set, I can search for "canada" and get all the visits that came from Canada, what is fine as well.
2. The result is shown in a grid using paginate(), what works well, too.

3. However, if I want to sort the grid by Origins -- for everything I read and tried so far -- I can't use the $model->with(...) approach. Instead, I have to use something like

   $visits = DB::table('visits') ->join('origins', 'origins.id', 'visits.origin_id') ->orderby($sort_column, $sort_az_za) ->paginate(10);

4. This is the thing: the search() will not work with the DB::table('visits') syntax and Visit::search("canada")->with(....)... approach does not allow me to sort by a field that is not in the Visits table.

The question is: how can I search and sort the results by any field I want?

I thought that it should be possible to extend Scout to search DB::table('TABLE') or to try to sort directly via ES -- though I would prefer to keep all the code bound to the "Laravel way".

If extending the DB::table('TABLE') is a way, could someone point me where to start?

Other than that, any other ideas?