adding support for collection_of association

lib/couchrest/casted_model.rb

@@ -2,19 +2,18 @@ module CouchRest
   module CastedModel
     
     def self.included(base)
+      base.send(:include, ::CouchRest::Mixins::AttributeProtection)
+      base.send(:include, ::CouchRest::Mixins::Attributes)
       base.send(:include, ::CouchRest::Mixins::Callbacks)
       base.send(:include, ::CouchRest::Mixins::Properties)
-      base.send(:include, ::CouchRest::Mixins::Assocations)
+      base.send(:include, ::CouchRest::Mixins::Associations)
       base.send(:attr_accessor, :casted_by)
     end
     
-    def initialize(keys={})
+    def initialize(keys = {})
       raise StandardError unless self.is_a? Hash
-      apply_all_property_defaults # defined in CouchRest::Mixins::Properties
+      prepare_all_attributes(keys)
       super()
-      keys.each do |k,v|
-        write_attribute(k.to_s, v)
-      end if keys
     end
     
     def []= key, value

lib/couchrest/mixins/associations.rb

@@ -1,4 +1,6 @@
 module CouchRest
+
+
   module Mixins
     module Associations
 
@@ -10,10 +12,13 @@ module CouchRest
 
       module ClassMethods
 
+        # Define an association that this object belongs to.
+        # 
         def belongs_to(attrib, *options)
           opts = {
             :foreign_key => attrib.to_s + '_id',
-            :class_name => attrib.to_s.camelcase
+            :class_name => attrib.to_s.camelcase,
+            :proxy => nil
           }
           case options.first
           when Hash
@@ -23,10 +28,10 @@ module CouchRest
           begin
             opts[:class] = opts[:class_name].constantize
           rescue
-            raise "Unable to convert belongs_to class name into Constant for #{self.name}##{attrib}"
+            raise "Unable to convert class name into Constant for #{self.name}##{attrib}"
           end
 
-          prop = property(opts[:foreign_key])
+          prop = property(opts[:foreign_key], opts)
 
           create_belongs_to_getter(attrib, prop, opts)
           create_belongs_to_setter(attrib, prop, opts)
@@ -34,10 +39,76 @@ module CouchRest
           prop
         end
 
+        # Provide access to a collection of objects where the associated
+        # property contains a list of the collection item ids.
+        #
+        # The following:
+        #
+        #     collection_of :groups
+        #
+        # creates a pseudo property called "groups" which allows access
+        # to a CollectionProxy object. Adding, replacing or removing entries in this
+        # proxy will cause the matching property array, in this case "group_ids", to
+        # be kept in sync.
+        #
+        # Any manual changes made to the collection ids property (group_ids), unless replaced, will require
+        # a reload of the CollectionProxy for the two sets of data to be in sync:
+        #
+        #     group_ids = ['123']
+        #     groups == [Group.get('123')]
+        #     group_ids << '321'
+        #     groups == [Group.get('123')]
+        #     groups(true) == [Group.get('123'), Group.get('321')]
+        #
+        # Of course, saving the parent record will store the collection ids as they are
+        # found.
+        #
+        # The CollectionProxy supports the following array functions, anything else will cause
+        # a mismatch between the collection objects and collection ids:
+        #
+        #     groups << obj
+        #     groups.push obj
+        #     groups.unshift obj
+        #     groups[0] = obj
+        #     groups.pop == obj
+        #     groups.shift == obj
+        #
+        # Addtional options match those of the the belongs_to method.
+        #
+        def collection_of(attrib, *options)
+          opts = {
+            :foreign_key => attrib.to_s.singularize + '_ids',
+            :class_name => attrib.to_s.singularize.camelcase,
+            :proxy => nil
+          }
+          case options.first
+          when Hash
+            opts.merge!(options.first)
+          end
+          begin
+            opts[:class] = opts[:class_name].constantize
+          rescue
+            raise "Unable to convert class name into Constant for #{self.name}##{attrib}"
+          end
+          opts[:readonly] = true
+
+          prop = property(opts[:foreign_key], [], opts)
+
+          create_collection_of_property_setter(attrib, prop, opts)
+          create_collection_of_getter(attrib, prop, opts)
+          create_collection_of_setter(attrib, prop, opts)
+
+          prop
+        end
+
+
+        private
+
         def create_belongs_to_getter(attrib, property, options)
+          base = options[:proxy] || options[:class_name]
           class_eval <<-EOS, __FILE__, __LINE__ + 1
             def #{attrib}
-              @#{attrib} ||= #{options[:class_name]}.get(self.#{options[:foreign_key]})
+              @#{attrib} ||= #{base}.get(self.#{options[:foreign_key]})
             end
           EOS
         end
@@ -45,14 +116,92 @@ module CouchRest
         def create_belongs_to_setter(attrib, property, options)
           class_eval <<-EOS, __FILE__, __LINE__ + 1
             def #{attrib}=(value)
-              @#{attrib} = value
               self.#{options[:foreign_key]} = value.nil? ? nil : value.id
+              @#{attrib} = value
             end
           EOS
         end
 
+        ### collection_of support methods
+
+        def create_collection_of_property_setter(attrib, property, options)
+          # ensure CollectionProxy is nil, ready to be reloaded on request
+          class_eval <<-EOS, __FILE__, __LINE__ + 1
+            def #{options[:foreign_key]}=(value)
+              @#{attrib} = nil
+              write_attribute("#{options[:foreign_key]}", value)
+            end
+          EOS
+        end
+
+        def create_collection_of_getter(attrib, property, options)
+          base = options[:proxy] || options[:class_name]
+          class_eval <<-EOS, __FILE__, __LINE__ + 1
+            def #{attrib}(reload = false)
+              return @#{attrib} unless @#{attrib}.nil? or reload
+              ary = self.#{options[:foreign_key]}.collect{|i| #{base}.get(i)}
+              @#{attrib} = ::CouchRest::CollectionProxy.new(ary, self, '#{options[:foreign_key]}')
+            end
+          EOS
+        end
+
+        def create_collection_of_setter(attrib, property, options)
+          class_eval <<-EOS, __FILE__, __LINE__ + 1
+            def #{attrib}=(value)
+              @#{attrib} = ::CouchRest::CollectionProxy.new(value, self, '#{options[:foreign_key]}')
+            end
+          EOS
+        end
+
+
       end
 
     end
   end
+
+  # Special proxy for a collection of items so that adding and removing
+  # to the list automatically updates the associated property.
+  class CollectionProxy < Array
+    attr_accessor :property
+    attr_accessor :casted_by
+
+    def initialize(array, casted_by, property)
+      self.property = property
+      self.casted_by = casted_by
+      array ||= []
+      casted_by[property.to_s] = [] # replace the original array!
+      array.each do |obj|
+        casted_by[property.to_s] << obj.id
+      end
+      super(array)
+    end
+    def << obj
+      casted_by[property.to_s] << obj.id
+      super(obj)
+    end
+    def push(obj)
+      casted_by[property.to_s].push obj.id
+      super(obj)
+    end
+    def unshift(obj)
+      casted_by[property.to_s].unshift obj.id
+      super(obj)
+    end
+
+    def []= index, obj
+      casted_by[property.to_s][index] = obj.id
+      super(index, obj)
+    end
+
+    def pop
+      casted_by[property.to_s].pop
+      super
+    end
+    def shift
+      casted_by[property.to_s].shift
+      super
+    end
+  end
+
+
 end