I'm still new to ActiveRecord, so forgive me if this is obvious, but
is it necessary in a relationship like the one below for each table to
refer to the other?  In this relationship, it would be sufficient for
the projects table to have a manager_id and it would not be necessary
for the managers table to have a project_id, or vice versa.  Does
ActiveRecord require both tables to refer to one another?

Thanks,
Carl

> * Added natural object-style assignment for has_one and belongs_to
>    associations. Consider the following model:
> 
>      class Project < ActiveRecord::Base
>        has_one :manager
>      end
> 
>      class Manager < ActiveRecord::Base
>        belongs_to :project
>      end
> 
>    Earlier, assignments would work like following regardless of which
> way the
>    assignment told the best story:
> 
>      active_record.manager_id = david.id
> 
>    Now you can do it either from the belonging side:
> 
>      david.project = active_record
> 
>    ...or from the having side:
> 
>      active_record.manager = david
> 
>    If the assignment happens from the having side, the assigned object is
>    automatically saved. So in the example above, the project_id
> attribute on
>    david would be set to the id of active_record, then david would be
> saved.