Justin does another great job explaining how to preload a rails association scope
by turning it into an association on the same model with a
clause, and then explains how to keep it DRY.
If you’re just using scopes, you end up creating an N+1 query when gathering the association.
positive can be reused in other scope-type statements,
such as the associatoins above.
Pre-loading (where we started) is like:
This solves the
N+1 problem using just scopes alone.