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Next generation associations

Correspondence aims to provide a base for creating associations between arbitrary ruby classes. With polyglotting databases on the rise, and association code specific to the Object Mapper you are using, Correspondence attempts to bridge the gap.

For example, if you have an ActiveRecord::Base class (lets call it User) that you have associated with a Ripple::Document like profile, implementing @user.profile is entirely manual. As are getters and queryiers like @user.profile= or @user.profile?. If you have multiple associations like this in your codebase it gets messy quick.


  • Not to be the be all and end all for linking ruby classes together
  • Provide a common pattern that is extensible and reusable to link classes together


  • Figure out final draft of DSL
  • Get base proxy class working (not just serving up the actual target)
  • one associations
    Support defining a class and method to find associated object
  • Lazy load and memoize associatated targets
  • All association customization down to the owner instance (I think this will be hard, maybe not though)
  • many assocations
    Support defining a class and finding multiple related objects
  • Arbitrary item many associations
    Support finding N arbitrary objects related to the querying object
  • Explore the possiblity of using this on an API like twitter, associating a User object with a set of tweets only via @user.tweets
  • Automagically inferring inverse relationships.


class User
  corresponds_with :profile

This will create a profile method on any instance of the user class. By default the profile method will call Profile.find(id) where id is a method on the user class.


  • :class_name specify a string for the association class name.
  • :class allows specifying a string, class, symbol or proc. Symbols must be class methods on the associating class, procs should resolve to the association class.
  • :on a symbol or string specifying the method that should be called on the associating class as a reference to the association. Defaults to :id.
  • :using a symbol or string that is the method that will be called on the association call. This method will be passed the results of :on. Defaults to :find.
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