Allow a polymorphic :source for has_many :through associations. Closes #7143 [protocool]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6408 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 127 insertions, 49 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index f0e5608b05..6fb00152a1 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -20,7 +20,13 @@ module ActiveRecord
       super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' on the polymorphic object '#{source_reflection.class_name}##{source_reflection.name}'.")
     end
   end
-
+  
+  class HasManyThroughAssociationPointlessSourceTypeError < ActiveRecordError #:nodoc:
+    def initialize(owner_class_name, reflection, source_reflection)
+      super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' with a :source_type option if the '#{reflection.through_reflection.class_name}##{source_reflection.name}' is not polymorphic.  Try removing :source_type on your association.")
+    end
+  end
+  
   class HasManyThroughSourceAssociationNotFoundError < ActiveRecordError #:nodoc:
     def initialize(reflection)
       through_reflection      = reflection.through_reflection
@@ -593,6 +599,8 @@ module ActiveRecord
       # * <tt>:source</tt>: Specifies the source association name used by <tt>has_many :through</tt> queries.  Only use it if the name cannot be 
       #   inferred from the association.  <tt>has_many :subscribers, :through => :subscriptions</tt> will look for either +:subscribers+ or
       #   +:subscriber+ on +Subscription+, unless a +:source+ is given.
+      # * <tt>:source_type</tt>: Specifies type of the source association used by <tt>has_many :through</tt> queries where the source association
+      #   is a polymorphic belongs_to.
       # * <tt>:uniq</tt> - if set to true, duplicates will be omitted from the collection. Useful in conjunction with :through.
       #
       # Option examples:
@@ -1151,7 +1159,7 @@ module ActiveRecord
             :class_name, :table_name, :foreign_key,
             :exclusively_dependent, :dependent,
             :select, :conditions, :include, :order, :group, :limit, :offset,
-            :as, :through, :source,
+            :as, :through, :source, :source_type,
             :uniq,
             :finder_sql, :counter_sql, 
             :before_add, :after_add, :before_remove, :after_remove, 
@@ -1555,58 +1563,113 @@ module ActiveRecord
                   case
                     when reflection.macro == :has_many && reflection.options[:through]
                       through_conditions = through_reflection.options[:conditions] ? "AND #{interpolate_sql(sanitize_sql(through_reflection.options[:conditions]))}" : ''
+                      
+                      jt_foreign_key = jt_as_extra = jt_source_extra = jt_sti_extra = nil 
+                      first_key = second_key = as_extra = nil 
+                      
                       if through_reflection.options[:as] # has_many :through against a polymorphic join
-                        polymorphic_foreign_key  = through_reflection.options[:as].to_s + '_id'
-                        polymorphic_foreign_type = through_reflection.options[:as].to_s + '_type'
-
-                        " LEFT OUTER JOIN %s ON (%s.%s = %s.%s AND %s.%s = %s) "  % [
-                          table_alias_for(through_reflection.klass.table_name, aliased_join_table_name),
-                          aliased_join_table_name, polymorphic_foreign_key,
-                          parent.aliased_table_name, parent.primary_key,
-                          aliased_join_table_name, polymorphic_foreign_type, klass.quote_value(parent.active_record.base_class.name)] +
-                        " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [table_name_and_alias,
-                          aliased_table_name, primary_key, aliased_join_table_name, options[:foreign_key] || reflection.klass.to_s.foreign_key
+                    ####polymorphic_foreign_key  = through_reflection.options[:as].to_s + '_id'
+                    ####polymorphic_foreign_type = through_reflection.options[:as].to_s + '_type'
+                    ####
+                    ####" LEFT OUTER JOIN %s ON (%s.%s = %s.%s AND %s.%s = %s) "  % [
+                    ####  table_alias_for(through_reflection.klass.table_name, aliased_join_table_name),
+                    ####  aliased_join_table_name, polymorphic_foreign_key,
+                    ####  parent.aliased_table_name, parent.primary_key,
+                    ####  aliased_join_table_name, polymorphic_foreign_type, klass.quote_value(parent.active_record.base_class.name)] +
+                    ####" LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [table_name_and_alias,
+                    ####  aliased_table_name, primary_key, aliased_join_table_name, options[:foreign_key] || reflection.klass.to_s.foreign_key
+                        jt_foreign_key = through_reflection.options[:as].to_s + '_id'
+                        jt_as_extra = " AND %s.%s = %s" % [
+                          aliased_join_table_name,
+                          reflection.active_record.connection.quote_column_name(through_reflection.options[:as].to_s + '_type'),
+                          klass.quote_value(parent.active_record.base_class.name)
                         ]
                       else
-                        if source_reflection.macro == :has_many && source_reflection.options[:as]
-                          " LEFT OUTER JOIN %s ON %s.%s = %s.%s "  % [
-                            table_alias_for(through_reflection.klass.table_name, aliased_join_table_name), aliased_join_table_name,
-                            through_reflection.primary_key_name,
-                            parent.aliased_table_name, parent.primary_key] +
-                          " LEFT OUTER JOIN %s ON %s.%s = %s.%s AND %s.%s = %s " % [
-                            table_name_and_alias,
-                            aliased_table_name, "#{source_reflection.options[:as]}_id", 
-                            aliased_join_table_name, options[:foreign_key] || primary_key,
-                            aliased_table_name, "#{source_reflection.options[:as]}_type", 
-                            klass.quote_value(source_reflection.active_record.base_class.name)
+                      ##if source_reflection.macro == :has_many && source_reflection.options[:as]
+                      ####" LEFT OUTER JOIN %s ON %s.%s = %s.%s "  % [
+                      ####  table_alias_for(through_reflection.klass.table_name, aliased_join_table_name), aliased_join_table_name,
+                      ####  through_reflection.primary_key_name,
+                      ####  parent.aliased_table_name, parent.primary_key] +
+                      ####" LEFT OUTER JOIN %s ON %s.%s = %s.%s AND %s.%s = %s " % [
+                      ####  table_name_and_alias,
+                      ####  aliased_table_name, "#{source_reflection.options[:as]}_id", 
+                      ####  aliased_join_table_name, options[:foreign_key] || primary_key,
+                      ####  aliased_table_name, "#{source_reflection.options[:as]}_type", 
+                      ####  klass.quote_value(source_reflection.active_record.base_class.name)
+                        jt_foreign_key = through_reflection.primary_key_name 
+                      end
+                        
+                      case source_reflection.macro
+                      when :has_many
+                        if source_reflection.options[:as] 
+                          first_key   = "#{source_reflection.options[:as]}_id" 
+                          second_key  = options[:foreign_key] || primary_key 
+                          as_extra    = " AND %s.%s = %s" % [
+                            aliased_table_name,
+                            reflection.active_record.connection.quote_column_name("#{source_reflection.options[:as]}_type"),  
+                            klass.quote_value(source_reflection.active_record.base_class.name) 
                           ]
                         else
-                          case source_reflection.macro
-                            when :belongs_to
-                              first_key  = primary_key
-                              second_key = source_reflection.options[:foreign_key] || klass.to_s.foreign_key
-                              extra      = nil
-                            when :has_many
-                              first_key  = through_reflection.klass.base_class.to_s.foreign_key
-                              second_key = options[:foreign_key] || primary_key
-                              extra      = through_reflection.klass.descends_from_active_record? ? nil :
-                                " AND %s.%s = %s" % [
-                                  aliased_join_table_name,
-                                  reflection.active_record.connection.quote_column_name(through_reflection.active_record.inheritance_column),
-                                  through_reflection.klass.quote_value(through_reflection.klass.name.demodulize)]
-                          end
-                          " LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s) "  % [
-                            table_alias_for(through_reflection.klass.table_name, aliased_join_table_name), 
-                            aliased_join_table_name, through_reflection.primary_key_name,
-                            parent.aliased_table_name, parent.primary_key, extra] +
-                          " LEFT OUTER JOIN %s ON (%s.%s = %s.%s) " % [
-                            table_name_and_alias,
-                            aliased_table_name, first_key, 
-                            aliased_join_table_name, second_key
+                      ####case source_reflection.macro
+                      ####  when :belongs_to
+                      ####    first_key  = primary_key
+                      ####    second_key = source_reflection.options[:foreign_key] || klass.to_s.foreign_key
+                      ####    extra      = nil
+                      ####  when :has_many
+                      ####    first_key  = through_reflection.klass.base_class.to_s.foreign_key
+                      ####    second_key = options[:foreign_key] || primary_key
+                      ####    extra      = through_reflection.klass.descends_from_active_record? ? nil :
+                      ####      " AND %s.%s = %s" % [
+                      ####        aliased_join_table_name,
+                      ####        reflection.active_record.connection.quote_column_name(through_reflection.active_record.inheritance_column),
+                      ####        through_reflection.klass.quote_value(through_reflection.klass.name.demodulize)]
+                      ####end
+                      ####" LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s) "  % [
+                      ####  table_alias_for(through_reflection.klass.table_name, aliased_join_table_name), 
+                      ####  aliased_join_table_name, through_reflection.primary_key_name,
+                      ####  parent.aliased_table_name, parent.primary_key, extra] +
+                      ####" LEFT OUTER JOIN %s ON (%s.%s = %s.%s) " % [
+                      ####  table_name_and_alias,
+                      ####  aliased_table_name, first_key, 
+                      ####  aliased_join_table_name, second_key
+                      ####]
+                          first_key   = through_reflection.klass.base_class.to_s.foreign_key
+                          second_key  = options[:foreign_key] || primary_key
+                        end
+                        
+                        unless through_reflection.klass.descends_from_active_record?
+                          jt_sti_extra = " AND %s.%s = %s" % [
+                            aliased_join_table_name,
+                            reflection.active_record.connection.quote_column_name(through_reflection.active_record.inheritance_column),
+                            through_reflection.klass.quote_value(through_reflection.klass.name.demodulize)]
+                        end
+                      when :belongs_to
+                        first_key = primary_key
+                        if reflection.options[:source_type]
+                          second_key = source_reflection.association_foreign_key
+                          jt_source_extra = " AND %s.%s = %s" % [
+                            aliased_join_table_name,
+                            reflection.active_record.connection.quote_column_name(reflection.source_reflection.options[:foreign_type]),
+                            klass.quote_value(reflection.options[:source_type])
                           ]
+                        else
+                          second_key = source_reflection.options[:foreign_key] || klass.to_s.foreign_key
                         end
                       end
-                    
+
+                      " LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s%s%s) " % [
+                        table_alias_for(through_reflection.klass.table_name, aliased_join_table_name),
+                        parent.aliased_table_name, reflection.active_record.connection.quote_column_name(parent.primary_key),
+                        aliased_join_table_name, reflection.active_record.connection.quote_column_name(jt_foreign_key), 
+                        jt_as_extra, jt_source_extra, jt_sti_extra
+                      ] +
+                      " LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s) " % [
+                        table_name_and_alias, 
+                        aliased_table_name, reflection.active_record.connection.quote_column_name(first_key),
+                        aliased_join_table_name, reflection.active_record.connection.quote_column_name(second_key),
+                        as_extra
+                      ]
+
                     when reflection.macro == :has_many && reflection.options[:as]
                       " LEFT OUTER JOIN %s ON %s.%s = %s.%s AND %s.%s = %s" % [
                         table_name_and_alias,
@@ -1652,6 +1715,7 @@ module ActiveRecord
             end
             
             protected
+
               def pluralize(table_name)
                 ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name
               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
index 26559d523a..a8ad52bef9 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -138,7 +138,11 @@ module ActiveRecord
 
         # Construct attributes for :through pointing to owner and associate.
         def construct_join_attributes(associate)
-          construct_owner_attributes(@reflection.through_reflection).merge(@reflection.source_reflection.primary_key_name => associate.id)
+          returning construct_owner_attributes(@reflection.through_reflection).merge(@reflection.source_reflection.primary_key_name => associate.id) do |join_attributes|
+            if @reflection.options[:source_type]
+              join_attributes.merge!(@reflection.source_reflection.options[:foreign_type] => associate.class.base_class.name.to_s)
+            end
+          end
         end
 
         # Associate attributes pointing to owner, quoted.
@@ -176,6 +180,12 @@ module ActiveRecord
           if @reflection.through_reflection.options[:as] || @reflection.source_reflection.macro == :belongs_to
             reflection_primary_key = @reflection.klass.primary_key
             source_primary_key     = @reflection.source_reflection.primary_key_name
+            if @reflection.options[:source_type]
+              polymorphic_join = "AND %s.%s = %s" % [
+                @reflection.through_reflection.table_name, "#{@reflection.source_reflection.options[:foreign_type]}",
+                @owner.class.quote_value(@reflection.options[:source_type])
+              ]
+            end
           else
             reflection_primary_key = @reflection.source_reflection.primary_key_name
             source_primary_key     = @reflection.klass.primary_key
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 2adadb29c5..62184eeff2 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -178,8 +178,12 @@ module ActiveRecord
           if source_reflection.nil?
             raise HasManyThroughSourceAssociationNotFoundError.new(self)
           end
+
+          if options[:source_type] && source_reflection.options[:polymorphic].nil?
+            raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
+          end
           
-          if source_reflection.options[:polymorphic]
+          if source_reflection.options[:polymorphic] && options[:source_type].nil?
             raise HasManyThroughAssociationPolymorphicError.new(active_record.name, self, source_reflection)
           end
           
@@ -193,7 +197,7 @@ module ActiveRecord
         def derive_class_name
           # get the class_name of the belongs_to association of the through reflection
           if through_reflection
-            source_reflection.class_name
+            options[:source_type] || source_reflection.class_name
           else
             class_name = name.to_s.camelize
             class_name = class_name.singularize if [ :has_many, :has_and_belongs_to_many ].include?(macro)