NoMethodError: undefined method `compact'

[did]

It happens when you've got 2 fields: belongs_to + many_to_many in a same model.

The problem is that we don't set the inverse_of property of a belongs_to field but we have to in order to avoid that error.

Better explanation here:
https://github.com/mongoid/mongoid/issues/1434

[rpocklin]

This makes sense and fixed the exact problem I had, but i'm wondering why this is conditionally optional, would it be less surprising just to ask for the inverse_of on belongs_to to always be defined explicitly?