public async Task <IReadOnlyCollection <Course> > GetCoursesAsync()
{
var results = await _context.AsQueryable()
.ToListAsync();
return(results.AsReadOnly());
}
/*
* this method let’s us to get whole non-materialized collection and
* perform some operations later
* (it’s slower than other methods because adds extra abstraction layer)
*/
public IQueryable <T> AsQueryable()
{
return(_collection.AsQueryable());
}