[Nitro] Q: refers_to / belongs_to vs. joins_many / many_to_many

Robert Mela rob at robmela.com
Tue Oct 16 09:23:28 EDT 2007


Poking about in og/relation/* and experimenting as I try to unravel this 
for http://robmela.com/cheatsheets/og_relations ( hopefully in a form 
that can be used in the rdocs for og or relation )


BelongsTo inherits from RefersTo but with this annotation in "enchant"


    target_class.ann!(:self)[:descendants] ||= []
    target_class.ann!(:self, :descendants) << [owner_class, foreign_key]

Something similar shows up in JoinsMany with a comment:

      # Add join class to ann(:descendants) to be able to use cascade 
deletes.

      owner_class.ann!(:self)[:descendants] ||= []
      owner_class.ann!(:self, :descendants) << [tmp_join_class, owner_key]


Is there a lack of symmetry here?

   RefersTo <= BelongsTo, with descendants annotation on the *latter*
   JoinsMany <= ManyToMany, with annotation on the *former*


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