Added preliminary support for join models [DHH] Added preliminary support for polymorphic associations [DHH] Refactored associations to use reflections to get DRYer, beware, major refactoring -- double check before deploying anything with this (all tests pass, but..)

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3213 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

17 files changed, 520 insertions, 446 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 397a89730a..44f00e0418 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,9 @@
 *SVN*
 
+* Added preliminary support for polymorphic associations [DHH]
+
+* Added preliminary support for join models [DHH]
+
 * Allow validate_uniqueness_of to be scoped by more than just one column.  #1559. [jeremy@jthopple.com, Marcel Molina Jr.]
 
 * Firebird: active? and reconnect! methods for handling stale connections.  #428 [Ken Kunz <kennethkunz@gmail.com>]
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 9aad0f028d..05c6c89501 100755
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -38,10 +38,10 @@ require 'active_record/base'
 require 'active_record/observer'
 require 'active_record/validations'
 require 'active_record/callbacks'
+require 'active_record/reflection'
 require 'active_record/associations'
 require 'active_record/aggregations'
 require 'active_record/transactions'
-require 'active_record/reflection'
 require 'active_record/timestamp'
 require 'active_record/acts/list'
 require 'active_record/acts/tree'
diff --git a/activerecord/lib/active_record/aggregations.rb b/activerecord/lib/active_record/aggregations.rb
index 6824df9b37..0970eaceee 100644
--- a/activerecord/lib/active_record/aggregations.rb
+++ b/activerecord/lib/active_record/aggregations.rb
@@ -1,7 +1,6 @@
 module ActiveRecord
   module Aggregations # :nodoc:
-    def self.append_features(base)
-      super
+    def self.included(base)
       base.extend(ClassMethods)
     end
 
@@ -128,6 +127,8 @@ module ActiveRecord
 
         reader_method(name, class_name, mapping)
         writer_method(name, class_name, mapping)
+        
+        create_reflection(:composed_of, part_id, options, self)
       end
 
       private
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 86b7101c64..2fcce6348e 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -4,6 +4,7 @@ require 'active_record/associations/belongs_to_association'
 require 'active_record/associations/belongs_to_polymorphic_association'
 require 'active_record/associations/has_one_association'
 require 'active_record/associations/has_many_association'
+require 'active_record/associations/has_many_through_association'
 require 'active_record/associations/has_and_belongs_to_many_association'
 require 'active_record/deprecated_associations'
 
@@ -341,57 +342,19 @@ module ActiveRecord
       #       'WHERE ps.post_id = #{id} AND ps.person_id = p.id ' +
       #       'ORDER BY p.first_name'
       def has_many(association_id, options = {}, &extension)
-        options.assert_valid_keys(
-          :foreign_key, :class_name, :exclusively_dependent, :dependent, 
-          :conditions, :order, :include, :finder_sql, :counter_sql, 
-          :before_add, :after_add, :before_remove, :after_remove, :extend,
-          :group, :as
-        )
+        reflection = create_has_many_reflection(association_id, options, &extension)
 
-        options[:extend] = create_extension_module(association_id, extension) if block_given?
+        configure_dependency_for_has_many(reflection)
 
-        association_name, association_class_name, association_class_primary_key_name =
-              associate_identification(association_id, options[:class_name], options[:foreign_key])
- 
-        require_association_class(association_class_name)
-
-        raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options.  You may specify one or the other.' if options[:dependent] and options[:exclusively_dependent]
-
-        if options[:exclusively_dependent]
-          options[:dependent] = :delete_all
-          #warn "The :exclusively_dependent option is deprecated.  Please use :dependent => :delete_all instead.")
-        end
-
-        # See HasManyAssociation#delete_records.  Dependent associations
-        # delete children, otherwise foreign key is set to NULL.
-        case options[:dependent]
-          when :destroy, true  
-            module_eval "before_destroy '#{association_name}.each { |o| o.destroy }'"
-          when :delete_all
-            module_eval "before_destroy { |record| #{association_class_name}.delete_all(%(#{association_class_primary_key_name} = \#{record.quoted_id})) }"
-          when :nullify
-            module_eval "before_destroy { |record| #{association_class_name}.update_all(%(#{association_class_primary_key_name} = NULL),  %(#{association_class_primary_key_name} = \#{record.quoted_id})) }"
-          when nil, false
-            # pass
-          else
-            raise ArgumentError, 'The :dependent option expects either true, :destroy, :delete_all, or :nullify' 
+        if options[:through]
+          collection_reader_method(reflection, HasManyThroughAssociation)
+        else
+          add_multiple_associated_save_callbacks(reflection.name)
+          add_association_callbacks(reflection.name, reflection.options)
+          collection_accessor_methods(reflection, HasManyAssociation)
         end
 
-
-        add_multiple_associated_save_callbacks(association_name)
-        add_association_callbacks(association_name, options)
-
-        collection_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, HasManyAssociation)
-        
-        # deprecated api
-        deprecated_collection_count_method(association_name)
-        deprecated_add_association_relation(association_name)
-        deprecated_remove_association_relation(association_name)
-        deprecated_has_collection_method(association_name)
-        deprecated_find_in_collection_method(association_name)
-        deprecated_find_all_in_collection_method(association_name)
-        deprecated_collection_create_method(association_name)
-        deprecated_collection_build_method(association_name)
+        add_deprecated_api_for_has_many(reflection.name)
       end
 
       # Adds the following methods for retrieval and query of a single associated object.
@@ -436,42 +399,27 @@ module ActiveRecord
       #   has_one :last_comment, :class_name => "Comment", :order => "posted_on"
       #   has_one :project_manager, :class_name => "Person", :conditions => "role = 'project_manager'"
       def has_one(association_id, options = {})
-        options.assert_valid_keys(:class_name, :foreign_key, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend)
-
-        association_name, association_class_name, association_class_primary_key_name =
-            associate_identification(association_id, options[:class_name], options[:foreign_key], false)
-
-        require_association_class(association_class_name)
+        reflection = create_has_one_reflection(association_id, options)
 
         module_eval do
           after_save <<-EOF
-            association = instance_variable_get("@#{association_name}")
+            association = instance_variable_get("@#{reflection.name}")
             unless association.nil?
-              association["#{association_class_primary_key_name}"] = id
+              association["#{reflection.primary_key_name}"] = id
               association.save(true)
-              association.send(:construct_sql)
             end
           EOF
         end
       
-        association_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, HasOneAssociation)
-        association_constructor_method(:build, association_name, association_class_name, association_class_primary_key_name, options, HasOneAssociation)
-        association_constructor_method(:create, association_name, association_class_name, association_class_primary_key_name, options, HasOneAssociation)
+        association_accessor_methods(reflection, HasOneAssociation)
+        association_constructor_method(:build,  reflection, HasOneAssociation)
+        association_constructor_method(:create, reflection, HasOneAssociation)
         
-        case options[:dependent]
-          when :destroy, true
-            module_eval "before_destroy '#{association_name}.destroy unless #{association_name}.nil?'"
-          when :nullify
-            module_eval "before_destroy '#{association_name}.update_attribute(\"#{association_class_primary_key_name}\", nil)'"
-          when nil, false
-            # pass
-          else
-            raise ArgumentError, "The :dependent option expects either :destroy or :nullify."
-        end
+        configure_dependency_for_has_one(reflection)
 
         # deprecated api
-        deprecated_has_association_method(association_name)
-        deprecated_association_comparison_method(association_name, association_class_name)
+        deprecated_has_association_method(reflection.name)
+        deprecated_association_comparison_method(reflection.name, reflection.class_name)
       end
 
       # Adds the following methods for retrieval and query for a single associated object that this object holds an id to.
@@ -517,52 +465,41 @@ module ActiveRecord
       #   belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id", 
       #              :conditions => 'discounts > #{payments_count}'
       def belongs_to(association_id, options = {})
-        options.assert_valid_keys(:class_name, :foreign_key, :foreign_type, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend, :polymorphic)
-
-        association_name, association_class_name, class_primary_key_name =
-            associate_identification(association_id, options[:class_name], options[:foreign_key], false)
-
-        association_class_primary_key_name = options[:foreign_key] || association_class_name.foreign_key
-
-        if options[:polymorphic]
-          options[:foreign_type] ||= association_class_name.underscore + "_type"
-
-          association_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, BelongsToPolymorphicAssociation)
+        reflection = create_belongs_to_reflection(association_id, options)
+        
+        if reflection.options[:polymorphic]
+          association_accessor_methods(reflection, BelongsToPolymorphicAssociation)
 
           module_eval do
             before_save <<-EOF
-              association = instance_variable_get("@#{association_name}")
+              association = instance_variable_get("@#{reflection.name}")
               if !association.nil? 
                 if association.new_record?
                   association.save(true)
-                  association.send(:construct_sql)
                 end
                 
                 if association.updated?
-                  self["#{association_class_primary_key_name}"] = association.id
-                  self["#{options[:foreign_type]}"] = ActiveRecord::Base.send(:class_name_of_active_record_descendant, association.class).to_s
+                  self["#{reflection.primary_key_name}"] = association.id
+                  self["#{reflection.options[:foreign_type]}"] = ActiveRecord::Base.send(:class_name_of_active_record_descendant, association.class).to_s
                 end
               end
             EOF
           end
         else
-          require_association_class(association_class_name)
-
-          association_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, BelongsToAssociation)
-          association_constructor_method(:build, association_name, association_class_name, association_class_primary_key_name, options, BelongsToAssociation)
-          association_constructor_method(:create, association_name, association_class_name, association_class_primary_key_name, options, BelongsToAssociation)
+          association_accessor_methods(reflection, BelongsToAssociation)
+          association_constructor_method(:build,  reflection, BelongsToAssociation)
+          association_constructor_method(:create, reflection, BelongsToAssociation)
 
           module_eval do
             before_save <<-EOF
-              association = instance_variable_get("@#{association_name}")
+              association = instance_variable_get("@#{reflection.name}")
               if !association.nil? 
                 if association.new_record?
                   association.save(true)
-                  association.send(:construct_sql)
                 end
                 
                 if association.updated?
-                  self["#{association_class_primary_key_name}"] = association.id
+                  self["#{reflection.primary_key_name}"] = association.id
                 end
               end            
             EOF
@@ -570,19 +507,19 @@ module ActiveRecord
       
           if options[:counter_cache]
             module_eval(
-              "after_create '#{association_class_name}.increment_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{association_class_primary_key_name})" +
-              " unless #{association_name}.nil?'"
+              "after_create '#{reflection.class_name}.increment_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{reflection.primary_key_name})" +
+              " unless #{reflection.name}.nil?'"
             )
 
             module_eval(
-              "before_destroy '#{association_class_name}.decrement_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{association_class_primary_key_name})" +
-              " unless #{association_name}.nil?'"
+              "before_destroy '#{reflection.class_name}.decrement_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{reflection.primary_key_name})" +
+              " unless #{reflection.name}.nil?'"
             )          
           end
 
           # deprecated api
-          deprecated_has_association_method(association_name)
-          deprecated_association_comparison_method(association_name, association_class_name)
+          deprecated_has_association_method(reflection.name)
+          deprecated_association_comparison_method(reflection.name, reflection.class_name)
         end
       end
 
@@ -663,43 +600,29 @@ module ActiveRecord
       #   has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :delete_sql => 
       #   'DELETE FROM developers_projects WHERE active=1 AND developer_id = #{id} AND project_id = #{record.id}'
       def has_and_belongs_to_many(association_id, options = {}, &extension)
-        options.assert_valid_keys(
-          :class_name, :table_name, :foreign_key, :association_foreign_key, :conditions, :include,
-          :join_table, :finder_sql, :delete_sql, :insert_sql, :order, :uniq, :before_add, :after_add, 
-          :before_remove, :after_remove, :extend
-        )
-
-        options[:extend] = create_extension_module(association_id, extension) if block_given?
-
-        association_name, association_class_name, association_class_primary_key_name =
-              associate_identification(association_id, options[:class_name], options[:foreign_key])
-
-        require_association_class(association_class_name)
-
-        options[:join_table] ||= join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(association_class_name))
-
-        add_multiple_associated_save_callbacks(association_name)
-      
-        collection_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, HasAndBelongsToManyAssociation)
+        reflection = create_has_and_belongs_to_many_reflection(association_id, options, &extension)
+        
+        add_multiple_associated_save_callbacks(reflection.name)
+        collection_accessor_methods(reflection, HasAndBelongsToManyAssociation)
 
         # Don't use a before_destroy callback since users' before_destroy
         # callbacks will be executed after the association is wiped out.
-        old_method = "destroy_without_habtm_shim_for_#{association_name}"
+        old_method = "destroy_without_habtm_shim_for_#{reflection.name}"
         class_eval <<-end_eval
           alias_method :#{old_method}, :destroy_without_callbacks
           def destroy_without_callbacks
-            #{association_name}.clear
+            #{reflection.name}.clear
             #{old_method}
           end
         end_eval
 
-        add_association_callbacks(association_name, options)
+        add_association_callbacks(reflection.name, options)
         
         # deprecated api
-        deprecated_collection_count_method(association_name)
-        deprecated_add_association_relation(association_name)
-        deprecated_remove_association_relation(association_name)
-        deprecated_has_collection_method(association_name)
+        deprecated_collection_count_method(reflection.name)
+        deprecated_add_association_relation(reflection.name)
+        deprecated_remove_association_relation(reflection.name)
+        deprecated_has_collection_method(reflection.name)
       end
 
       private
@@ -713,93 +636,81 @@ module ActiveRecord
           table_name_prefix + join_table + table_name_suffix
         end
         
-        def associate_identification(association_id, association_class_name, foreign_key, plural = true)
-          if association_class_name !~ /::/
-            association_class_name = type_name_with_module(
-              association_class_name || 
-                Inflector.camelize(plural ? Inflector.singularize(association_id.id2name) : association_id.id2name)
-            )
-          end
-
-          primary_key_name = foreign_key || name.foreign_key
-        
-          return association_id.id2name, association_class_name, primary_key_name
-        end
-        
-        def association_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, association_proxy_class)
-          define_method(association_name) do |*params|
+        def association_accessor_methods(reflection, association_proxy_class)
+          define_method(reflection.name) do |*params|
             force_reload = params.first unless params.empty?
-            association = instance_variable_get("@#{association_name}")
-            if association.nil? or force_reload
-              association = association_proxy_class.new(self,
-                association_name, association_class_name,
-                association_class_primary_key_name, options)
+            association = instance_variable_get("@#{reflection.name}")
+
+            if association.nil? || force_reload
+              association = association_proxy_class.new(self, reflection)
               retval = association.reload
               unless retval.nil?
-                instance_variable_set("@#{association_name}", association)
+                instance_variable_set("@#{reflection.name}", association)
               else
-                instance_variable_set("@#{association_name}", nil)
+                instance_variable_set("@#{reflection.name}", nil)
                 return nil
               end
             end
             association
           end
 
-          define_method("#{association_name}=") do |new_value|
-            association = instance_variable_get("@#{association_name}")
+          define_method("#{reflection.name}=") do |new_value|
+            association = instance_variable_get("@#{reflection.name}")
             if association.nil?
-              association = association_proxy_class.new(self,
-                association_name, association_class_name,
-                association_class_primary_key_name, options)
+              association = association_proxy_class.new(self, reflection)
             end
+
             association.replace(new_value)
+
             unless new_value.nil?
-              instance_variable_set("@#{association_name}", association)
+              instance_variable_set("@#{reflection.name}", association)
             else
-              instance_variable_set("@#{association_name}", nil)
+              instance_variable_set("@#{reflection.name}", nil)
               return nil
             end
+
             association
           end
 
-          define_method("set_#{association_name}_target") do |target|
+          define_method("set_#{reflection.name}_target") do |target|
             return if target.nil?
-            association = association_proxy_class.new(self,
-              association_name, association_class_name,
-              association_class_primary_key_name, options)
+            association = association_proxy_class.new(self, reflection)
             association.target = target
-            instance_variable_set("@#{association_name}", association)
+            instance_variable_set("@#{reflection.name}", association)
           end
         end
 
-        def collection_accessor_methods(association_name, association_class_name, association_class_primary_key_name, options, association_proxy_class)
-          define_method(association_name) do |*params|
+        def collection_reader_method(reflection, association_proxy_class)
+          define_method(reflection.name) do |*params|
             force_reload = params.first unless params.empty?
-            association = instance_variable_get("@#{association_name}")
+            association = instance_variable_get("@#{reflection.name}")
+
             unless association.respond_to?(:loaded?)
-              association = association_proxy_class.new(self,
-                association_name, association_class_name,
-                association_class_primary_key_name, options)
-              instance_variable_set("@#{association_name}", association)
+              association = association_proxy_class.new(self, reflection)
+              instance_variable_set("@#{reflection.name}", association)
             end
+
             association.reload if force_reload
+
             association
           end
+        end
 
-          define_method("#{association_name}=") do |new_value|
-            association = instance_variable_get("@#{association_name}")
+        def collection_accessor_methods(reflection, association_proxy_class)
+          collection_reader_method(reflection, association_proxy_class)
+
+          define_method("#{reflection.name}=") do |new_value|
+            association = instance_variable_get("@#{reflection.name}")
             unless association.respond_to?(:loaded?)
-              association = association_proxy_class.new(self,
-                association_name, association_class_name,
-                association_class_primary_key_name, options)
-              instance_variable_set("@#{association_name}", association)
+              association = association_proxy_class.new(self, reflection)
+              instance_variable_set("@#{reflection.name}", association)
             end
             association.replace(new_value)
             association
           end
 
-          define_method("#{Inflector.singularize(association_name)}_ids=") do |new_value|
-            send("#{association_name}=", association_class_name.constantize.find(new_value))
+          define_method("#{reflection.name.to_s.singularize}_ids=") do |new_value|
+            send("#{reflection.name}=", reflection.class_name.constantize.find(new_value))
           end
         end
 
@@ -847,17 +758,15 @@ module ActiveRecord
           after_update(after_callback)
         end
 
-        def association_constructor_method(constructor, association_name, association_class_name, association_class_primary_key_name, options, association_proxy_class)
-          define_method("#{constructor}_#{association_name}") do |*params|
+        def association_constructor_method(constructor, reflection, association_proxy_class)
+          define_method("#{constructor}_#{reflection.name}") do |*params|
             attributees      = params.first unless params.empty?
             replace_existing = params[1].nil? ? true : params[1]
-            association      = instance_variable_get("@#{association_name}")
+            association      = instance_variable_get("@#{reflection.name}")
 
             if association.nil?
-              association = association_proxy_class.new(self,
-                association_name, association_class_name,
-                association_class_primary_key_name, options)
-              instance_variable_set("@#{association_name}", association)
+              association = association_proxy_class.new(self, reflection)
+              instance_variable_set("@#{reflection.name}", association)
             end
 
             if association_proxy_class == HasOneAssociation
@@ -910,6 +819,118 @@ module ActiveRecord
         end
 
 
+        def configure_dependency_for_has_many(reflection)
+          if reflection.options[:dependent] && reflection.options[:exclusively_dependent]
+            raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options.  You may specify one or the other.'
+          end
+
+          if reflection.options[:exclusively_dependent]
+            reflection.options[:dependent] = :delete_all
+            #warn "The :exclusively_dependent option is deprecated.  Please use :dependent => :delete_all instead.")
+          end
+
+          # See HasManyAssociation#delete_records.  Dependent associations
+          # delete children, otherwise foreign key is set to NULL.
+          case reflection.options[:dependent]
+            when :destroy, true  
+              module_eval "before_destroy '#{reflection.name}.each { |o| o.destroy }'"
+            when :delete_all
+              module_eval "before_destroy { |record| #{reflection.class_name}.delete_all(%(#{reflection.primary_key_name} = \#{record.quoted_id})) }"
+            when :nullify
+              module_eval "before_destroy { |record| #{reflection.class_name}.update_all(%(#{reflection.primary_key_name} = NULL),  %(#{reflection.primary_key_name} = \#{record.quoted_id})) }"
+            when nil, false
+              # pass
+            else
+              raise ArgumentError, 'The :dependent option expects either true, :destroy, :delete_all, or :nullify' 
+          end
+        end
+        
+        def configure_dependency_for_has_one(reflection)
+          case reflection.options[:dependent]
+            when :destroy, true
+              module_eval "before_destroy '#{reflection.name}.destroy unless #{reflection.name}.nil?'"
+            when :nullify
+              module_eval "before_destroy '#{reflection.name}.update_attribute(\"#{reflection.primary_key_name}\", nil)'"
+            when nil, false
+              # pass
+            else
+              raise ArgumentError, "The :dependent option expects either :destroy or :nullify."
+          end
+        end
+        
+        
+        def add_deprecated_api_for_has_many(association_name)
+          deprecated_collection_count_method(association_name)
+          deprecated_add_association_relation(association_name)
+          deprecated_remove_association_relation(association_name)
+          deprecated_has_collection_method(association_name)
+          deprecated_find_in_collection_method(association_name)
+          deprecated_find_all_in_collection_method(association_name)
+          deprecated_collection_create_method(association_name)
+          deprecated_collection_build_method(association_name)
+        end
+
+        def create_has_many_reflection(association_id, options, &extension)
+          options.assert_valid_keys(
+            :foreign_key, :class_name, :exclusively_dependent, :dependent, 
+            :conditions, :order, :include, :finder_sql, :counter_sql, 
+            :before_add, :after_add, :before_remove, :after_remove, :extend,
+            :group, :as, :through
+          )
+
+          options[:extend] = create_extension_module(association_id, extension) if block_given?
+
+          reflection = create_reflection(:has_many, association_id, options, self)
+          reflection.require_class
+
+          reflection
+        end
+
+        def create_has_one_reflection(association_id, options)
+          options.assert_valid_keys(
+            :class_name, :foreign_key, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend
+          )
+
+          reflection = create_reflection(:has_one, association_id, options, self)
+          reflection.require_class
+
+          reflection
+        end
+
+        def create_belongs_to_reflection(association_id, options)
+          options.assert_valid_keys(
+            :class_name, :foreign_key, :foreign_type, :remote, :conditions, :order, :include, :dependent, 
+            :counter_cache, :extend, :polymorphic
+          )
+          
+          reflection = create_reflection(:belongs_to, association_id, options, self)
+
+          if options[:polymorphic]
+            reflection.options[:foreign_type] ||= reflection.class_name.underscore + "_type"
+          else
+            reflection.require_class
+          end
+
+          reflection
+        end
+        
+        def create_has_and_belongs_to_many_reflection(association_id, options, &extension)
+          options.assert_valid_keys(
+            :class_name, :table_name, :foreign_key, :association_foreign_key, :conditions, :include,
+            :join_table, :finder_sql, :delete_sql, :insert_sql, :order, :uniq, :before_add, :after_add, 
+            :before_remove, :after_remove, :extend
+          )
+
+          options[:extend] = create_extension_module(association_id, extension) if block_given?
+
+          reflection = create_reflection(:has_and_belongs_to_many, association_id, options, self)
+          reflection.require_class
+
+          reflection.options[:join_table] ||= join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(reflection.class_name))
+          
+          reflection
+        end
+
         def reflect_on_included_associations(associations)
           [ associations ].flatten.collect { |association| reflect_on_association(association.to_s.intern) }
         end
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index 7ee567e0b4..a66248ff2e 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -18,6 +18,7 @@ module ActiveRecord
       def <<(*records)
         result = true
         load_target
+
         @owner.transaction do
           flatten_deeper(records).each do |record|
             raise_on_type_mismatch(record)
@@ -28,7 +29,7 @@ module ActiveRecord
           end
         end
 				
-        result and self
+        result && self
       end
 
       alias_method :push, :<<
@@ -60,11 +61,13 @@ module ActiveRecord
       # Removes all records from this association.  Returns +self+ so method calls may be chained.
       def clear
         return self if length.zero? # forces load_target if hasn't happened already
-        if @options[:exclusively_dependent]
+
+        if @reflection.options[:exclusively_dependent]
           destroy_all
         else          
           delete_all
         end
+
         self
       end
       
@@ -124,14 +127,6 @@ module ActiveRecord
       end
 
       private
-        def raise_on_type_mismatch(record)
-          raise ActiveRecord::AssociationTypeMismatch, "#{@association_class} expected, got #{record.class}" unless record.is_a?(@association_class)
-        end
-
-        def target_obsolete?
-          false
-        end
-
         # Array#flatten has problems with recursive arrays. Going one level deeper solves the majority of the problems.
         def flatten_deeper(array)
           array.collect { |element| element.respond_to?(:flatten) ? element.flatten : element }.flatten
@@ -155,8 +150,8 @@ module ActiveRecord
         end
         
         def callbacks_for(callback_name)
-          full_callback_name = "#{callback_name.to_s}_for_#{@association_name.to_s}"
-          @owner.class.read_inheritable_attribute(full_callback_name.to_sym) or []
+          full_callback_name = "#{callback_name}_for_#{@reflection.name}"
+          @owner.class.read_inheritable_attribute(full_callback_name.to_sym) || []
         end
         
     end
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index 8a7d925d0d..75f9184aa2 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -5,15 +5,9 @@ module ActiveRecord
       alias_method :proxy_extend, :extend
       instance_methods.each { |m| undef_method m unless m =~ /(^__|^nil\?|^proxy_respond_to\?|^proxy_extend|^send)/ }
 
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
-        @owner = owner
-        @options = options
-        @association_name = association_name
-        @association_class = eval(association_class_name, nil, __FILE__, __LINE__)
-        @association_class_primary_key_name = association_class_primary_key_name
-
-        proxy_extend(options[:extend]) if options[:extend]
-
+      def initialize(owner, reflection)
+        @owner, @reflection = owner, reflection
+        proxy_extend(reflection.options[:extend]) if reflection.options[:extend]
         reset
       end
       
@@ -28,6 +22,11 @@ module ActiveRecord
         other === @target
       end
 
+      def reset
+        @target = nil
+        @loaded = false
+      end
+
       def reload
         reset
         load_target
@@ -45,14 +44,14 @@ module ActiveRecord
         @target
       end
       
-      def target=(t)
-        @target = t
-        @loaded = true
+      def target=(target)
+        @target = target
+        loaded
       end
       
       protected
         def dependent?
-          @options[:dependent] || false
+          @reflection.options[:dependent] || false
         end
         
         def quoted_record_ids(records)
@@ -68,7 +67,7 @@ module ActiveRecord
         end
 
         def sanitize_sql(sql)
-          @association_class.send(:sanitize_sql, sql)
+          @reflection.klass.send(:sanitize_sql, sql)
         end
 
         def extract_options_from_args!(args)
@@ -84,13 +83,14 @@ module ActiveRecord
         def load_target
           if !@owner.new_record? || foreign_key_present
             begin
-              @target = find_target if not loaded?
+              @target = find_target if !loaded?
             rescue ActiveRecord::RecordNotFound
               reset
             end
           end
-          @loaded = true if @target
-          @target
+
+          loaded if target
+          target
         end
 
         # Can be overwritten by associations that might have the foreign key available for an association without
@@ -100,7 +100,9 @@ module ActiveRecord
         end
 
         def raise_on_type_mismatch(record)
-          raise ActiveRecord::AssociationTypeMismatch, "#{@association_class} expected, got #{record.class}" unless record.is_a?(@association_class)
+          unless record.is_a?(@reflection.klass)
+            raise ActiveRecord::AssociationTypeMismatch, "#{@reflection.class_name} expected, got #{record.class}"
+          end
         end
     end
   end
diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index 39d128aef1..804a7ebf21 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -1,41 +1,27 @@
 module ActiveRecord
   module Associations
     class BelongsToAssociation < AssociationProxy #:nodoc:
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
-        super        
-        construct_sql        
-      end
-      
-      def reset
-        @target = nil
-        @loaded = false
-      end
-
       def create(attributes = {})
-        record = @association_class.create(attributes)
-        replace(record, true)
-        record
+        replace(@reflection.klass.create(attributes))
       end
 
       def build(attributes = {})
-        record = @association_class.new(attributes)
-        replace(record, true)
-        record
+        replace(@reflection.klass.new(attributes))
       end
 
-      def replace(obj, dont_save = false)
-        if obj.nil?
-          @target = @owner[@association_class_primary_key_name] = nil
+      def replace(record)
+        if record.nil?
+          @target = @owner[@reflection.primary_key_name] = nil
         else
-          raise_on_type_mismatch(obj) unless obj.nil?
+          raise_on_type_mismatch(record)
 
-          @target = (AssociationProxy === obj ? obj.target : obj)
-          @owner[@association_class_primary_key_name] = obj.id unless obj.new_record?
+          @target = (AssociationProxy === record ? record.target : record)
+          @owner[@reflection.primary_key_name] = record.id unless record.new_record?
           @updated = true
         end
-        @loaded = true
 
-        return (@target.nil? ? nil : self)
+        loaded
+        record
       end
       
       def updated?
@@ -44,27 +30,15 @@ module ActiveRecord
       
       private
         def find_target
-          if @options[:conditions]
-            @association_class.find(
-              @owner[@association_class_primary_key_name], 
-              :conditions => interpolate_sql(@options[:conditions]),
-              :include    => @options[:include]
-            )
-          else
-            @association_class.find(@owner[@association_class_primary_key_name], :include => @options[:include])
-          end
+          @reflection.klass.find(
+            @owner[@reflection.primary_key_name], 
+            :conditions => @reflection.options[:conditions] ? interpolate_sql(@reflection.options[:conditions]) : nil,
+            :include    => @reflection.options[:include]
+          )
         end
 
         def foreign_key_present
-          !@owner[@association_class_primary_key_name].nil?
-        end
-
-        def target_obsolete?
-          @owner[@association_class_primary_key_name] != @target.id
-        end
-        
-        def construct_sql
-          @finder_sql = "#{@association_class.table_name}.#{@association_class.primary_key} = #{@owner.id}"
+          !@owner[@reflection.primary_key_name].nil?
         end
     end
   end
diff --git a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
index e2a7f1a58e..6c2b9b89fd 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -1,69 +1,49 @@
 module ActiveRecord
   module Associations
-    class BelongsToPolymorphicAssociation < BelongsToAssociation #:nodoc:
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
-        @owner = owner
-        @options = options
-        @association_name = association_name
-        @association_class_primary_key_name = association_class_primary_key_name
-
-        proxy_extend(options[:extend]) if options[:extend]
-
-        reset
-      end
-      
-      def create(attributes = {})
-        raise ActiveRecord::ActiveRecordError, "Can't create an abstract polymorphic object"
-      end
-
-      def build(attributes = {})
-        raise ActiveRecord::ActiveRecordError, "Can't build an abstract polymorphic object"
-      end
-
-      def replace(obj, dont_save = false)
-        if obj.nil?
-          @target = @owner[@association_class_primary_key_name] = @owner[@options[:foreign_type]] = nil
+    class BelongsToPolymorphicAssociation < AssociationProxy #:nodoc:
+      def replace(record)
+        if record.nil?
+          @target = @owner[@reflection.primary_key_name] = @owner[@reflection.options[:foreign_type]] = nil
         else
-          @target = (AssociationProxy === obj ? obj.target : obj)
+          @target = (AssociationProxy === record ? record.target : record)
 
-          unless obj.new_record?
-            @owner[@association_class_primary_key_name] = obj.id
-            @owner[@options[:foreign_type]] = ActiveRecord::Base.send(:class_name_of_active_record_descendant, obj.class).to_s
+          unless record.new_record?
+            @owner[@reflection.primary_key_name] = record.id
+            @owner[@reflection.options[:foreign_type]] = ActiveRecord::Base.send(:class_name_of_active_record_descendant, record.class).to_s
           end
 
           @updated = true
         end
 
-        @loaded = true
+        loaded
+        record
+      end
 
-        return (@target.nil? ? nil : self)
+      def updated?
+        @updated
       end
-      
+
       private
         def find_target
           return nil if association_class.nil?
 
-          if @options[:conditions]
+          if @reflection.options[:conditions]
             association_class.find(
-              @owner[@association_class_primary_key_name], 
-              :conditions => interpolate_sql(@options[:conditions]),
-              :include    => @options[:include]
+              @owner[@reflection.primary_key_name], 
+              :conditions => interpolate_sql(@reflection.options[:conditions]),
+              :include    => @reflection.options[:include]
             )
           else
-            association_class.find(@owner[@association_class_primary_key_name], :include => @options[:include])
+            association_class.find(@owner[@reflection.primary_key_name], :include => @reflection.options[:include])
           end
         end
 
         def foreign_key_present
-          !@owner[@association_class_primary_key_name].nil?
+          !@owner[@reflection.primary_key_name].nil?
         end
 
-        def target_obsolete?
-          @owner[@association_class_primary_key_name] != @target.id
-        end
-        
         def association_class
-          @owner[@options[:foreign_type]] ? @owner[@options[:foreign_type]].constantize : nil
+          @owner[@reflection.options[:foreign_type]] ? @owner[@reflection.options[:foreign_type]].constantize : nil
         end
     end
   end
diff --git a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
index 4bfa759666..417b0905f4 100644
--- a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
@@ -1,20 +1,14 @@
 module ActiveRecord
   module Associations
     class HasAndBelongsToManyAssociation < AssociationCollection #:nodoc:
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
+      def initialize(owner, reflection)
         super
-
-        @association_foreign_key = options[:association_foreign_key] || association_class_name.foreign_key
-        @association_table_name = options[:table_name] || @association_class.table_name
-        @join_table = options[:join_table]
-        @order = options[:order]
-
         construct_sql
       end
  
       def build(attributes = {})
         load_target
-        record = @association_class.new(attributes)
+        record = @reflection.klass.new(attributes)
         @target << record
         record
       end
@@ -27,7 +21,7 @@ module ActiveRecord
         options = Base.send(:extract_options_from_args!, args)
 
         # If using a custom finder_sql, scan the entire collection.
-        if @options[:finder_sql]
+        if @reflection.options[:finder_sql]
           expects_array = args.first.kind_of?(Array)
           ids = args.flatten.compact.uniq
 
@@ -40,60 +34,64 @@ module ActiveRecord
           end
         else
           conditions = "#{@finder_sql}"
+
           if sanitized_conditions = sanitize_sql(options[:conditions])
             conditions << " AND (#{sanitized_conditions})"
           end
+
           options[:conditions] = conditions
           options[:joins] = @join_sql
           options[:readonly] ||= false
 
-          if options[:order] && @options[:order]
-            options[:order] = "#{options[:order]}, #{@options[:order]}"
-          elsif @options[:order]
-            options[:order] = @options[:order]
+          if options[:order] && @reflection.options[:order]
+            options[:order] = "#{options[:order]}, #{@reflection.options[:order]}"
+          elsif @reflection.options[:order]
+            options[:order] = @reflection.options[:order]
           end
 
           # Pass through args exactly as we received them.
           args << options
-          @association_class.find(*args)
+          @reflection.klass.find(*args)
         end
       end      
 
       def push_with_attributes(record, join_attributes = {})
         raise_on_type_mismatch(record)
         join_attributes.each { |key, value| record[key.to_s] = value }
+
         callback(:before_add, record)
         insert_record(record) unless @owner.new_record?
         @target << record
         callback(:after_add, record)
+
         self
       end
       
       alias :concat_with_attributes :push_with_attributes
 
       def size
-        @options[:uniq] ? count_records : super
+        @reflection.options[:uniq] ? count_records : super
       end
       
       protected
         def method_missing(method, *args, &block)
-          if @target.respond_to?(method) || (!@association_class.respond_to?(method) && Class.respond_to?(method))
+          if @target.respond_to?(method) || (!@reflection.klass.respond_to?(method) && Class.respond_to?(method))
             super
           else
-            @association_class.with_scope(:find => { :conditions => @finder_sql, :joins => @join_sql, :readonly => false }) do
-              @association_class.send(method, *args, &block)
+            @reflection.klass.with_scope(:find => { :conditions => @finder_sql, :joins => @join_sql, :readonly => false }) do
+              @reflection.klass.send(method, *args, &block)
             end
           end
         end
             
         def find_target
-          if @options[:finder_sql]
-            records = @association_class.find_by_sql(@finder_sql)
+          if @reflection.options[:finder_sql]
+            records = @reflection.klass.find_by_sql(@finder_sql)
           else
-            records = find(:all, :include => @options[:include])
+            records = find(:all, :include => @reflection.options[:include])
           end
           
-          @options[:uniq] ? uniq(records) : records
+          @reflection.options[:uniq] ? uniq(records) : records
         end
         
         def count_records
@@ -105,16 +103,16 @@ module ActiveRecord
             return false unless record.save
           end
 
-          if @options[:insert_sql]
-            @owner.connection.execute(interpolate_sql(@options[:insert_sql], record))
+          if @reflection.options[:insert_sql]
+            @owner.connection.execute(interpolate_sql(@reflection.options[:insert_sql], record))
           else
-            columns = @owner.connection.columns(@join_table, "#{@join_table} Columns")
+            columns = @owner.connection.columns(@reflection.options[:join_table], "#{@reflection.options[:join_table]} Columns")
 
             attributes = columns.inject({}) do |attributes, column|
               case column.name
-                when @association_class_primary_key_name
+                when @reflection.primary_key_name
                   attributes[column.name] = @owner.quoted_id
-                when @association_foreign_key
+                when @reflection.association_foreign_key
                   attributes[column.name] = record.quoted_id
                 else
                   if record.attributes.has_key?(column.name)
@@ -126,7 +124,7 @@ module ActiveRecord
             end
 
             sql =
-              "INSERT INTO #{@join_table} (#{@owner.send(:quoted_column_names, attributes).join(', ')}) " +
+              "INSERT INTO #{@reflection.options[:join_table]} (#{@owner.send(:quoted_column_names, attributes).join(', ')}) " +
               "VALUES (#{attributes.values.join(', ')})"
 
             @owner.connection.execute(sql)
@@ -136,26 +134,26 @@ module ActiveRecord
         end
         
         def delete_records(records)
-          if sql = @options[:delete_sql]
+          if sql = @reflection.options[:delete_sql]
             records.each { |record| @owner.connection.execute(interpolate_sql(sql, record)) }
           else
             ids = quoted_record_ids(records)
-            sql = "DELETE FROM #{@join_table} WHERE #{@association_class_primary_key_name} = #{@owner.quoted_id} AND #{@association_foreign_key} IN (#{ids})"
+            sql = "DELETE FROM #{@reflection.options[:join_table]} WHERE #{@reflection.primary_key_name} = #{@owner.quoted_id} AND #{@reflection.association_foreign_key} IN (#{ids})"
             @owner.connection.execute(sql)
           end
         end
 
         def construct_sql
-          interpolate_sql_options!(@options, :finder_sql)
+          interpolate_sql_options!(@reflection.options, :finder_sql)
 
-          if @options[:finder_sql]
-            @finder_sql = @options[:finder_sql]
+          if @reflection.options[:finder_sql]
+            @finder_sql = @reflection.options[:finder_sql]
           else
-            @finder_sql = "#{@join_table}.#{@association_class_primary_key_name} = #{@owner.quoted_id} "
-            @finder_sql << " AND (#{interpolate_sql(@options[:conditions])})" if @options[:conditions]
+            @finder_sql = "#{@reflection.options[:join_table]}.#{@reflection.primary_key_name} = #{@owner.quoted_id} "
+            @finder_sql << " AND (#{interpolate_sql(@reflection.options[:conditions])})" if @reflection.options[:conditions]
           end
 
-          @join_sql = "JOIN #{@join_table} ON #{@association_class.table_name}.#{@association_class.primary_key} = #{@join_table}.#{@association_foreign_key}"
+          @join_sql = "JOIN #{@reflection.options[:join_table]} ON #{@reflection.klass.table_name}.#{@reflection.klass.primary_key} = #{@reflection.options[:join_table]}.#{@reflection.association_foreign_key}"
         end
         
     end
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 465e1f8c72..f4a08420b7 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -1,10 +1,9 @@
 module ActiveRecord
   module Associations
     class HasManyAssociation < AssociationCollection #:nodoc:
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
+      def initialize(owner, reflection)
         super
-        @conditions = sanitize_sql(options[:conditions])
-
+        @conditions = sanitize_sql(reflection.options[:conditions])
         construct_sql
       end
 
@@ -13,8 +12,8 @@ module ActiveRecord
           attributes.collect { |attr| create(attr) }
         else
           load_target
-          record = @association_class.new(attributes)
-          record[@association_class_primary_key_name] = @owner.id unless @owner.new_record?
+          record = @reflection.klass.new(attributes)
+          record[@reflection.primary_key_name] = @owner.id unless @owner.new_record?
           @target << record
           record
         end
@@ -22,13 +21,13 @@ module ActiveRecord
 
       # DEPRECATED.
       def find_all(runtime_conditions = nil, orderings = nil, limit = nil, joins = nil)
-        if @options[:finder_sql]
-          @association_class.find_by_sql(@finder_sql)
+        if @reflection.options[:finder_sql]
+          @reflection.klass.find_by_sql(@finder_sql)
         else
           conditions = @finder_sql
           conditions += " AND (#{sanitize_sql(runtime_conditions)})" if runtime_conditions
-          orderings ||= @options[:order]
-          @association_class.find_all(conditions, orderings, limit, joins)
+          orderings ||= @reflection.options[:order]
+          @reflection.klass.find_all(conditions, orderings, limit, joins)
         end
       end
 
@@ -39,14 +38,14 @@ module ActiveRecord
 
       # Count the number of associated records. All arguments are optional.
       def count(runtime_conditions = nil)
-        if @options[:counter_sql]
-          @association_class.count_by_sql(@counter_sql)
-        elsif @options[:finder_sql]
-          @association_class.count_by_sql(@finder_sql)
+        if @reflection.options[:counter_sql]
+          @reflection.klass.count_by_sql(@counter_sql)
+        elsif @reflection.options[:finder_sql]
+          @reflection.klass.count_by_sql(@finder_sql)
         else
           sql = @finder_sql
           sql += " AND (#{sanitize_sql(runtime_conditions)})" if runtime_conditions
-          @association_class.count(sql)
+          @reflection.klass.count(sql)
         end
       end
 
@@ -54,7 +53,7 @@ module ActiveRecord
         options = Base.send(:extract_options_from_args!, args)
 
         # If using a custom finder_sql, scan the entire collection.
-        if @options[:finder_sql]
+        if @reflection.options[:finder_sql]
           expects_array = args.first.kind_of?(Array)
           ids = args.flatten.compact.uniq
 
@@ -72,49 +71,49 @@ module ActiveRecord
           end
           options[:conditions] = conditions
 
-          if options[:order] && @options[:order]
-            options[:order] = "#{options[:order]}, #{@options[:order]}"
-          elsif @options[:order]
-            options[:order] = @options[:order]
+          if options[:order] && @reflection.options[:order]
+            options[:order] = "#{options[:order]}, #{@reflection.options[:order]}"
+          elsif @reflection.options[:order]
+            options[:order] = @reflection.options[:order]
           end
 
           # Pass through args exactly as we received them.
           args << options
-          @association_class.find(*args)
+          @reflection.klass.find(*args)
         end
       end
       
       protected
         def method_missing(method, *args, &block)
-          if @target.respond_to?(method) || (!@association_class.respond_to?(method) && Class.respond_to?(method))
+          if @target.respond_to?(method) || (!@reflection.klass.respond_to?(method) && Class.respond_to?(method))
             super
           else
-            @association_class.with_scope(
+            @reflection.klass.with_scope(
               :find => {
                 :conditions => @finder_sql, 
                 :joins      => @join_sql, 
                 :readonly   => false
               },
               :create => {
-                @association_class_primary_key_name => @owner.id
+                @reflection.primary_key_name => @owner.id
               }
             ) do
-              @association_class.send(method, *args, &block)
+              @reflection.klass.send(method, *args, &block)
             end
           end
         end
             
         def find_target
-          if @options[:finder_sql]
-            @association_class.find_by_sql(@finder_sql)
+          if @reflection.options[:finder_sql]
+            @reflection.klass.find_by_sql(@finder_sql)
           else
-            @association_class.find(:all, 
+            @reflection.klass.find(:all, 
               :conditions => @finder_sql,
-              :order      => @options[:order], 
-              :limit      => @options[:limit],
-              :joins      => @options[:joins],
-              :include    => @options[:include],
-              :group      => @options[:group]
+              :order      => @reflection.options[:order], 
+              :limit      => @reflection.options[:limit],
+              :joins      => @reflection.options[:joins],
+              :include    => @reflection.options[:include],
+              :group      => @reflection.options[:group]
             )
           end
         end
@@ -122,10 +121,10 @@ module ActiveRecord
         def count_records
           count = if has_cached_counter?
             @owner.send(:read_attribute, cached_counter_attribute_name)
-          elsif @options[:counter_sql]
-            @association_class.count_by_sql(@counter_sql)
+          elsif @reflection.options[:counter_sql]
+            @reflection.klass.count_by_sql(@counter_sql)
           else
-            @association_class.count(@counter_sql)
+            @reflection.klass.count(@counter_sql)
           end
           
           @target = [] and loaded if count == 0
@@ -138,22 +137,22 @@ module ActiveRecord
         end
 
         def cached_counter_attribute_name
-          "#{@association_name}_count"
+          "#{@reflection.name}_count"
         end
 
         def insert_record(record)
-          record[@association_class_primary_key_name] = @owner.id
+          record[@reflection.primary_key_name] = @owner.id
           record.save
         end
 
         def delete_records(records)
-          if @options[:dependent]
+          if @reflection.options[:dependent]
             records.each { |r| r.destroy }
           else
             ids = quoted_record_ids(records)
-            @association_class.update_all(
-              "#{@association_class_primary_key_name} = NULL", 
-              "#{@association_class_primary_key_name} = #{@owner.quoted_id} AND #{@association_class.primary_key} IN (#{ids})"
+            @reflection.klass.update_all(
+              "#{@reflection.primary_key_name} = NULL", 
+              "#{@reflection.primary_key_name} = #{@owner.quoted_id} AND #{@reflection.klass.primary_key} IN (#{ids})"
             )
           end
         end
@@ -164,25 +163,25 @@ module ActiveRecord
 
         def construct_sql
           case
-            when @options[:as]
+            when @reflection.options[:finder_sql]
+              @finder_sql = interpolate_sql(@reflection.options[:finder_sql])
+
+            when @reflection.options[:as]
               @finder_sql = 
-                "#{@association_class.table_name}.#{@options[:as]}_id = #{@owner.quoted_id} AND " + 
-                "#{@association_class.table_name}.#{@options[:as]}_type = '#{ActiveRecord::Base.send(:class_name_of_active_record_descendant, @owner.class).to_s}'"
+                "#{@reflection.klass.table_name}.#{@reflection.options[:as]}_id = #{@owner.quoted_id} AND " + 
+                "#{@reflection.klass.table_name}.#{@reflection.options[:as]}_type = '#{ActiveRecord::Base.send(:class_name_of_active_record_descendant, @owner.class).to_s}'"
               @finder_sql << " AND (#{interpolate_sql(@conditions)})" if @conditions
 
-            when @options[:finder_sql]
-              @finder_sql = interpolate_sql(@options[:finder_sql])
-
             else
-              @finder_sql = "#{@association_class.table_name}.#{@association_class_primary_key_name} = #{@owner.quoted_id}"
+              @finder_sql = "#{@reflection.klass.table_name}.#{@reflection.primary_key_name} = #{@owner.quoted_id}"
               @finder_sql << " AND (#{interpolate_sql(@conditions)})" if @conditions
           end
 
-          if @options[:counter_sql]
-            @counter_sql = interpolate_sql(@options[:counter_sql])
-          elsif @options[:finder_sql]
-            @options[:counter_sql] = @options[:finder_sql].gsub(/SELECT (.*) FROM/i, "SELECT COUNT(*) FROM")
-            @counter_sql = interpolate_sql(@options[:counter_sql])
+          if @reflection.options[:counter_sql]
+            @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
+          elsif @reflection.options[:finder_sql]
+            @reflection.options[:counter_sql] = @reflection.options[:finder_sql].gsub(/SELECT (.*) FROM/i, "SELECT COUNT(*) FROM")
+            @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
           else
             @counter_sql = @finder_sql
           end
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
new file mode 100644
index 0000000000..ca4496b32e
--- /dev/null
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -0,0 +1,80 @@
+module ActiveRecord
+  module Associations
+    class HasManyThroughAssociation < AssociationProxy #:nodoc:
+      def find(*args)
+        options = Base.send(:extract_options_from_args!, args)
+
+        conditions = "#{@finder_sql}"
+        if sanitized_conditions = sanitize_sql(options[:conditions])
+          conditions << " AND (#{sanitized_conditions})"
+        end
+        options[:conditions] = conditions
+
+        if options[:order] && @reflection.options[:order]
+          options[:order] = "#{options[:order]}, #{@reflection.options[:order]}"
+        elsif @reflection.options[:order]
+          options[:order] = @reflection.options[:order]
+        end
+
+        # Pass through args exactly as we received them.
+        args << options
+        @reflection.klass.find(*args)
+      end
+
+      def reset
+        @target = []
+        @loaded = false
+      end
+
+      protected
+        def method_missing(method, *args, &block)
+          if @target.respond_to?(method) || (!@reflection.klass.respond_to?(method) && Class.respond_to?(method))
+            super
+          else
+            @reflection.klass.with_scope(construct_scope) { @reflection.klass.send(method, *args, &block) }
+          end
+        end
+            
+        def find_target
+          @reflection.klass.find(:all, 
+            :conditions => construct_conditions,
+            :from       => construct_from,
+            :order      => @reflection.options[:order], 
+            :limit      => @reflection.options[:limit],
+            :joins      => @reflection.options[:joins],
+            :group      => @reflection.options[:group]
+          )
+        end
+
+        def construct_conditions
+          through_reflection = @owner.class.reflections[@reflection.options[:through]]
+          
+          if through_reflection.options[:as]
+            conditions = 
+              "#{@reflection.table_name}.#{@reflection.klass.primary_key} = #{through_reflection.table_name}.#{@reflection.klass.to_s.foreign_key} " +
+              "AND #{through_reflection.table_name}.#{through_reflection.options[:as]}_id = #{@owner.quoted_id} " + 
+              "AND #{through_reflection.table_name}.#{through_reflection.options[:as]}_type = '#{ActiveRecord::Base.send(:class_name_of_active_record_descendant, @owner.class).to_s}'"
+          else
+            conditions = 
+              "#{@reflection.klass.table_name}.#{@reflection.klass.primary_key} = #{through_reflection.table_name}.#{@reflection.klass.to_s.foreign_key} " +
+              "AND #{through_reflection.table_name}.#{@owner.to_s.foreign_key} = #{@owner.quoted_id}"
+          end
+          
+          conditions << " AND (#{interpolate_sql(sanitize_sql(@reflection.options[:conditions]))})" if @reflection.options[:conditions]
+          
+          return conditions
+        end
+
+        def construct_from
+          "#{@reflection.table_name}, #{@owner.class.reflections[@reflection.options[:through]].table_name}"
+        end
+        
+        def construct_scope
+          {
+            :find   => { :conditions => construct_conditions },
+            :create => { @reflection.primary_key_name => @owner.id }
+          }
+        end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 8f7857ebea..17483305fc 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -1,9 +1,8 @@
 module ActiveRecord
   module Associations
     class HasOneAssociation < BelongsToAssociation #:nodoc:
-      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
+      def initialize(owner, reflection)
         super
-
         construct_sql
       end
 
@@ -14,12 +13,12 @@ module ActiveRecord
       end
 
       def build(attributes = {}, replace_existing = true)
-        record = @association_class.new(attributes)
+        record = @reflection.klass.new(attributes)
 
         if replace_existing
           replace(record, true) 
         else
-          record[@association_class_primary_key_name] = @owner.id unless @owner.new_record?
+          record[@reflection.primary_key_name] = @owner.id unless @owner.new_record?
           self.target = record
         end
 
@@ -28,12 +27,13 @@ module ActiveRecord
 
       def replace(obj, dont_save = false)
         load_target
+
         unless @target.nil?
           if dependent? && !dont_save && @target != obj
             @target.destroy unless @target.new_record?
             @owner.clear_association_cache
           else
-            @target[@association_class_primary_key_name] = nil
+            @target[@reflection.primary_key_name] = nil
             @target.save unless @owner.new_record?
           end
         end
@@ -43,11 +43,12 @@ module ActiveRecord
         else
           raise_on_type_mismatch(obj)
           
-          obj[@association_class_primary_key_name] = @owner.id unless @owner.new_record?
+          obj[@reflection.primary_key_name] = @owner.id unless @owner.new_record?
           @target = (AssociationProxy === obj ? obj.target : obj)
         end
 
         @loaded = true
+
         unless @owner.new_record? or obj.nil? or dont_save
           return (obj.save ? self : false)
         else
@@ -57,16 +58,16 @@ module ActiveRecord
             
       private
         def find_target
-          @association_class.find(:first, :conditions => @finder_sql, :order => @options[:order], :include => @options[:include])
-        end
-
-        def target_obsolete?
-          false
+          @reflection.klass.find(:first, 
+            :conditions => @finder_sql, 
+            :order      => @reflection.options[:order], 
+            :include    => @reflection.options[:include]
+          )
         end
 
         def construct_sql
-          @finder_sql = "#{@association_class.table_name}.#{@association_class_primary_key_name} = #{@owner.quoted_id}"
-          @finder_sql << " AND (#{sanitize_sql(@options[:conditions])})" if @options[:conditions]
+          @finder_sql = "#{@reflection.table_name}.#{@reflection.primary_key_name} = #{@owner.quoted_id}"
+          @finder_sql << " AND (#{sanitize_sql(@reflection.options[:conditions])})" if @reflection.options[:conditions]
           @finder_sql
         end
     end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index e79dd45d88..4232b18450 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -930,12 +930,17 @@ module ActiveRecord #:nodoc:
         end
 
         def construct_finder_sql(options)
-          sql  = "SELECT #{options[:select] || '*'} FROM #{table_name} "
+          sql  = "SELECT #{options[:select] || '*'} "
+          sql << "FROM #{options[:from] || table_name} "
+
           add_joins!(sql, options)
           add_conditions!(sql, options[:conditions])
+
           sql << " GROUP BY #{options[:group]} " if options[:group]
           sql << " ORDER BY #{options[:order]} " if options[:order]
+
           add_limit!(sql, options)
+
           sql
         end
 
@@ -1180,7 +1185,7 @@ module ActiveRecord #:nodoc:
         end
 
         def validate_find_options(options)
-          options.assert_valid_keys [:conditions, :include, :joins, :limit, :offset, :order, :select, :readonly, :group]
+          options.assert_valid_keys [:conditions, :include, :joins, :limit, :offset, :order, :select, :readonly, :group, :from]
         end
 
         def encode_quoted_value(value)
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index affbb65ca6..87a05086fc 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -1,36 +1,7 @@
 module ActiveRecord
   module Reflection # :nodoc:
-    def self.append_features(base)
-      super
+    def self.included(base)
       base.extend(ClassMethods)
-
-      base.class_eval do
-        class << self
-          alias_method :composed_of_without_reflection, :composed_of
-
-          def composed_of_with_reflection(part_id, options = {})
-            composed_of_without_reflection(part_id, options)
-            reflect_on_all_aggregations << AggregateReflection.new(:composed_of, part_id, options, self)
-          end
-
-          alias_method :composed_of, :composed_of_with_reflection
-        end
-      end
-
-      for association_type in %w( belongs_to has_one has_many has_and_belongs_to_many )
-        base.module_eval <<-"end_eval"
-          class << self
-            alias_method :#{association_type}_without_reflection, :#{association_type}
-      
-            def #{association_type}_with_reflection(association_id, options = {}, &block)
-              #{association_type}_without_reflection(association_id, options, &block)      
-              reflect_on_all_associations << AssociationReflection.new(:#{association_type}, association_id, options, self)
-            end
-      
-            alias_method :#{association_type}, :#{association_type}_with_reflection
-          end
-        end_eval
-      end
     end
 
     # Reflection allows you to interrogate Active Record classes and objects about their associations and aggregations.
@@ -39,26 +10,39 @@ module ActiveRecord
     #
     # You can find the interface for the AggregateReflection and AssociationReflection classes in the abstract MacroReflection class.
     module ClassMethods
+      def create_reflection(macro, name, options, active_record)
+        case macro
+          when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
+            reflections[name] = AssociationReflection.new(macro, name, options, active_record)
+          when :composed_of
+            reflections[name] = AggregateReflection.new(macro, name, options, active_record)
+        end
+      end
+      
+      def reflections
+        read_inheritable_attribute(:reflections) or write_inheritable_attribute(:reflections, {})
+      end
+      
       # Returns an array of AggregateReflection objects for all the aggregations in the class.
       def reflect_on_all_aggregations
-        read_inheritable_attribute(:aggregations) or write_inheritable_attribute(:aggregations, [])
+        reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) }
       end
 
       # Returns the AggregateReflection object for the named +aggregation+ (use the symbol). Example:
       #   Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection
       def reflect_on_aggregation(aggregation)
-        reflect_on_all_aggregations.find { |reflection| reflection.name == aggregation } unless reflect_on_all_aggregations.nil?
+        reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
       end
 
       # Returns an array of AssociationReflection objects for all the aggregations in the class.
       def reflect_on_all_associations
-        read_inheritable_attribute(:associations) or write_inheritable_attribute(:associations, [])
+        reflections.values.select { |reflection| reflection.is_a?(AssociationReflection) }
       end
 
       # Returns the AssociationReflection object for the named +aggregation+ (use the symbol). Example:
       #   Account.reflect_on_association(:owner) # returns the owner AssociationReflection
       def reflect_on_association(association)
-        reflect_on_all_associations.find { |reflection| reflection.name == association }
+        reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
       end
     end
 
@@ -92,6 +76,14 @@ module ActiveRecord
       # Returns the class for the macro, so "composed_of :balance, :class_name => 'Money'" would return the Money class and
       # "has_many :clients" would return the Client class.
       def klass() end
+        
+      def class_name
+        @class_name ||= name_to_class_name(name.id2name)
+      end
+
+      def require_class
+        require_association(class_name.underscore) if class_name
+      end
 
       def ==(other_aggregation)
         name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
@@ -102,7 +94,7 @@ module ActiveRecord
     # Holds all the meta-data about an aggregation as it was specified in the Active Record class.
     class AggregateReflection < MacroReflection #:nodoc:
       def klass
-        Object.const_get(options[:class_name] || name_to_class_name(name.id2name))
+        @klass ||= Object.const_get(class_name)
       end
 
       private
@@ -114,22 +106,40 @@ module ActiveRecord
     # Holds all the meta-data about an association as it was specified in the Active Record class.
     class AssociationReflection < MacroReflection #:nodoc:
       def klass
-        @klass ||= active_record.send(:compute_type, (name_to_class_name(name.id2name)))
+        @klass ||= active_record.send(:compute_type, class_name)
       end
 
       def table_name
         @table_name ||= klass.table_name
       end
 
+      def primary_key_name
+        return @primary_key_name if @primary_key_name
+        
+        case macro
+          when :belongs_to
+            @primary_key_name = options[:foreign_key] || class_name.foreign_key
+          else
+            @primary_key_name = options[:foreign_key] || active_record.name.foreign_key
+        end
+      end
+      
+      def association_foreign_key
+        @association_foreign_key ||= @options[:association_foreign_key] || class_name.foreign_key
+      end
+
       private
         def name_to_class_name(name)
           if name =~ /::/
             name
           else
-            unless class_name = options[:class_name]
+            if options[:class_name]
+              class_name = options[:class_name]
+            else
               class_name = name.to_s.camelize
-              class_name = class_name.singularize if [:has_many, :has_and_belongs_to_many].include?(macro)
+              class_name = class_name.singularize if [ :has_many, :has_and_belongs_to_many ].include?(macro)
             end
+
             active_record.send(:type_name_with_module, class_name)
           end
         end
diff --git a/activerecord/test/associations_interface_test.rb b/activerecord/test/associations_join_model_test.rb
index 5f9447294a..303c33679f 100644
--- a/activerecord/test/associations_interface_test.rb
+++ b/activerecord/test/associations_join_model_test.rb
@@ -4,14 +4,18 @@ require 'fixtures/tagging'
 require 'fixtures/post'
 require 'fixtures/comment'
 
-class AssociationsInterfaceTest < Test::Unit::TestCase
+class AssociationsJoinModelTest < Test::Unit::TestCase
   fixtures :posts, :comments, :tags, :taggings
 
-  def test_post_having_a_single_tag_through_has_many
+  def test_polymorphic_has_many
     assert_equal taggings(:welcome_general), posts(:welcome).taggings.first
   end
 
-  def test_post_having_a_single_tag_through_belongs_to
+  def test_polymorphic_belongs_to
     assert_equal posts(:welcome), posts(:welcome).taggings.first.taggable
   end
+
+  def test_polymorphic_has_many_going_through_join_model
+    assert_equal tags(:general), posts(:welcome).tags.first
+  end
 end
diff --git a/activerecord/test/fixtures/post.rb b/activerecord/test/fixtures/post.rb
index 61249c43e0..97b25179f5 100644
--- a/activerecord/test/fixtures/post.rb
+++ b/activerecord/test/fixtures/post.rb
@@ -21,6 +21,7 @@ class Post < ActiveRecord::Base
   has_and_belongs_to_many :special_categories, :join_table => "categories_posts"
 
   has_many :taggings, :as => :taggable
+  has_many :tags, :through => :taggings
 
   def self.what_are_you
     'a post...'
diff --git a/activerecord/test/reflection_test.rb b/activerecord/test/reflection_test.rb
index c3117b8c5d..7af9e8c70d 100644
--- a/activerecord/test/reflection_test.rb
+++ b/activerecord/test/reflection_test.rb
@@ -60,10 +60,9 @@ class ReflectionTest < Test::Unit::TestCase
       :composed_of, :gps_location, { }, Customer
     )
 
-    assert_equal(
-      [ reflection_for_address, reflection_for_balance, reflection_for_gps_location ],
-      Customer.reflect_on_all_aggregations
-    )
+    assert Customer.reflect_on_all_aggregations.include?(reflection_for_gps_location)
+    assert Customer.reflect_on_all_aggregations.include?(reflection_for_balance)
+    assert Customer.reflect_on_all_aggregations.include?(reflection_for_address)
 
     assert_equal reflection_for_address, Customer.reflect_on_aggregation(:address)