ContentGroupers concern

app/models/character.rb

@@ -14,27 +14,11 @@ class Character < ActiveRecord::Base
 
   belongs_to :universe
 
-  # TODO: Rip all this out into a HasSiblings concern (or better yet, generalize it into a HasRelationship concern)
-  has_many :siblingships
-  has_many :siblings, through: :siblingships
-  accepts_nested_attributes_for :siblingships, reject_if: :all_blank, allow_destroy: true
-  has_many :inverse_siblingships, class_name: 'Siblingship', foreign_key: 'sibling_id'
-  has_many :inverse_siblings, through: :inverse_siblingships, source: :character
+  include HasContentGroupers
 
-  # Fathership
-  has_many :fatherships
-  has_many :fathers, through: :fatherships
-  accepts_nested_attributes_for :fatherships, reject_if: :all_blank, allow_destroy: true
-  has_many :inverse_fatherships, class_name: 'Fathership', foreign_key: 'father_id'
-  has_many :inverse_fathers, through: :inverse_fatherships, source: :character
-
-  # TODO: design DSL in concern to condense these 5-line blocks into 1
-  # Mothership
-  has_many :motherships
-  has_many :mothers, through: :motherships
-  accepts_nested_attributes_for :motherships, reject_if: :all_blank, allow_destroy: true
-  has_many :inverse_motherships, class_name: 'Mothership', foreign_key: 'mother_id'
-  has_many :inverse_mothers, through: :inverse_motherships, source: :character
+  relates :siblings, with: :siblingships
+  relates :fathers,  with: :fatherships
+  relates :mothers,  with: :motherships
 
 
 

app/models/concerns/has_content_groupers.rb

@@ -0,0 +1,20 @@
+require 'active_support/concern'
+
+module HasContentGroupers
+  extend ActiveSupport::Concern
+
+  included do
+    # relates :siblings, with: :siblingships
+    # Defines :siblings and :siblingships relations, their inverses, and accepts nested attributes for the connecting class
+    def self.relates relation, with: nil
+      singularized_relation = relation.to_s.singularize
+      connecting_class = with
+
+      has_many connecting_class
+      has_many relation, through: connecting_class
+      accepts_nested_attributes_for connecting_class, reject_if: :all_blank, allow_destroy: true
+      has_many "inverse_#{connecting_class}".to_sym, class_name: "#{singularized_relation.capitalize}", foreign_key: "#{singularized_relation}_id"
+      has_many "inverse_#{relation}".to_sym, through: "inverse_#{connecting_class}".to_sym, source: :character
+    end
+  end
+end

app/models/mothership.rb

@@ -1,2 +0,0 @@
-class Mothership < ActiveRecord::Base
-end