EF Core 1.0 does not support automatic lazy loading and eager loading related objects in the same way that EF6 did. Lazy loading does make data access easier and it cuts the code you have to write to reach that data significantly, so its good to see that it is still listed as a priority item here on EF’s Roadmap.
Until then, the way to eager load related objects, is by the .Include() and .ThenInclude() methods. Here are two examples.
var leagues = db.Leagues .Include(l => l.Teams) .ThenInclude(t => t.Players) .ToList(); var leagues = from d in db.Leagues.Include(l => l.Teams) select d;