Work-in progress for providing better join model support and polymorphic associations

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3209 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 84 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index 17b8cc6446..8a7d925d0d 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -76,7 +76,6 @@ module ActiveRecord
         end
         
       private
-        
         def method_missing(method, *args, &block)
           load_target
           @target.send(method, *args, &block)
diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index 528c42cea7..39d128aef1 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -1,7 +1,6 @@
 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        
@@ -43,9 +42,6 @@ module ActiveRecord
         @updated
       end
       
-      protected
-
-
       private
         def find_target
           if @options[:conditions]
diff --git a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
new file mode 100644
index 0000000000..e2a7f1a58e
--- /dev/null
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -0,0 +1,70 @@
+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
+        else
+          @target = (AssociationProxy === obj ? obj.target : obj)
+
+          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
+          end
+
+          @updated = true
+        end
+
+        @loaded = true
+
+        return (@target.nil? ? nil : self)
+      end
+      
+      private
+        def find_target
+          return nil if association_class.nil?
+
+          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
+        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 association_class
+          @owner[@options[:foreign_type]] ? @owner[@options[:foreign_type]].constantize : nil
+        end
+    end
+  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 288742d965..465e1f8c72 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -163,11 +163,19 @@ module ActiveRecord
         end
 
         def construct_sql
-          if @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 << " AND (#{interpolate_sql(@conditions)})" if @conditions
+          case
+            when @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}'"
+              @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 << " AND (#{interpolate_sql(@conditions)})" if @conditions
           end
 
           if @options[:counter_sql]
@@ -176,8 +184,7 @@ module ActiveRecord
             @options[:counter_sql] = @options[:finder_sql].gsub(/SELECT (.*) FROM/i, "SELECT COUNT(*) FROM")
             @counter_sql = interpolate_sql(@options[:counter_sql])
           else
-            @counter_sql = "#{@association_class.table_name}.#{@association_class_primary_key_name} = #{@owner.quoted_id}"
-            @counter_sql << " AND (#{interpolate_sql(@conditions)})" if @conditions
+            @counter_sql = @finder_sql
           end
         end
     end