Merge branch 'master' of git://github.com/rails/rails

9 files changed, 58 insertions, 25 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 9e7d609d19..0952ea2829 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1575,7 +1575,7 @@ module ActiveRecord
       #   has_and_belongs_to_many :categories, :join_table => "prods_cats"
       #   has_and_belongs_to_many :categories, :readonly => true
       #   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}'
+      #   "DELETE FROM developers_projects WHERE active=1 AND developer_id = #{id} AND project_id = #{record.id}"
       def has_and_belongs_to_many(name, options = {}, &extension)
         Builder::HasAndBelongsToMany.build(self, name, options, &extension)
       end
diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index 9e6d9e73c5..6cc401e6cc 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -42,10 +42,6 @@ module ActiveRecord
           select_value ||= options[:uniq] && "DISTINCT #{reflection.quoted_table_name}.*"
         end
 
-        if reflection.macro == :has_and_belongs_to_many
-          select_value ||= reflection.klass.arel_table[Arel.star]
-        end
-
         select_value
       end
 
@@ -68,7 +64,12 @@ module ActiveRecord
           end
 
           if reflection.source_macro == :belongs_to
-            key         = reflection.association_primary_key
+            if reflection.options[:polymorphic]
+              key = reflection.association_primary_key(klass)
+            else
+              key = reflection.association_primary_key
+            end
+
             foreign_key = reflection.foreign_key
           else
             key         = reflection.foreign_key
diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index 58c9648ce8..97f531d064 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -45,7 +45,11 @@ module ActiveRecord
         end
 
         def replace_keys(record)
-          owner[reflection.foreign_key] = record && record[reflection.association_primary_key]
+          if record
+            owner[reflection.foreign_key] = record[reflection.association_primary_key(record.class)]
+          else
+            owner[reflection.foreign_key] = nil
+          end
         end
 
         def foreign_key_present?
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb
index 6ba3d45aff..3181ca9a32 100644
--- a/activerecord/lib/active_record/associations/collection_proxy.rb
+++ b/activerecord/lib/active_record/associations/collection_proxy.rb
@@ -46,7 +46,7 @@ module ActiveRecord
 
       delegate :select, :find, :first, :last,
                :build, :create, :create!,
-               :concat, :delete_all, :destroy_all, :delete, :destroy, :uniq,
+               :concat, :replace, :delete_all, :destroy_all, :delete, :destroy, :uniq,
                :sum, :count, :size, :length, :empty?,
                :any?, :many?, :include?,
                :to => :@association
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index ed71b5e7d4..a404a5edd7 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -66,7 +66,6 @@ module ActiveRecord
           @primary_key ||= ''
           self.original_primary_key = @primary_key
           value &&= value.to_s
-          connection_pool.primary_keys[table_name] = value
           self.primary_key = block_given? ? instance_eval(&block) : value
         end
       end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 558b341c06..78159d13d4 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -707,6 +707,10 @@ module ActiveRecord #:nodoc:
 
       # Returns an array of column objects for the table associated with this class.
       def columns
+        if defined?(@primary_key)
+          connection_pool.primary_keys[table_name] ||= primary_key
+        end
+
         connection_pool.columns[table_name]
       end
 
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 89179779e3..120ff0cac6 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -211,11 +211,9 @@ module ActiveRecord
         @association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
       end
 
-      def association_primary_key
-        @association_primary_key ||=
-          options[:primary_key] ||
-          !options[:polymorphic] && klass.primary_key ||
-          'id'
+      # klass option is necessary to support loading polymorphic associations
+      def association_primary_key(klass = nil)
+        options[:primary_key] || (klass || self.klass).primary_key
       end
 
       def active_record_primary_key
@@ -463,17 +461,15 @@ module ActiveRecord
       # We want to use the klass from this reflection, rather than just delegate straight to
       # the source_reflection, because the source_reflection may be polymorphic. We still
       # need to respect the source_reflection's :primary_key option, though.
-      def association_primary_key
-        @association_primary_key ||= begin
-          # Get the "actual" source reflection if the immediate source reflection has a
-          # source reflection itself
-          source_reflection = self.source_reflection
-          while source_reflection.source_reflection
-            source_reflection = source_reflection.source_reflection
-          end
-
-          source_reflection.options[:primary_key] || klass.primary_key
+      def association_primary_key(klass = self.klass)
+        # Get the "actual" source reflection if the immediate source reflection has a
+        # source reflection itself
+        source_reflection = self.source_reflection
+        while source_reflection.source_reflection
+          source_reflection = source_reflection.source_reflection
         end
+
+        source_reflection.options[:primary_key] || klass.primary_key
       end
 
       # Gets an array of possible <tt>:through</tt> source reflection names:
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index a11b7a3864..670ba0987d 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -37,6 +37,35 @@ module ActiveRecord
       relation
     end
 
+    # Works in two unique ways.
+    # 
+    # First: takes a block so it can be used just like Array#select.
+    #
+    #   Model.scoped.select { |m| m.field == value }
+    #
+    # This will build an array of objects from the database for the scope,
+    # converting them into an array and iterating through them using Array#select.
+    #
+    # Second: Modifies the SELECT statement for the query so that only certain
+    # fields are retrieved:
+    #
+    #   >> Model.select(:field)
+    #   => [#<Model field:value>]
+    #
+    # Although in the above example it looks as though this method returns an
+    # array, it actually returns a relation object and can have other query
+    # methods appended to it, such as the other methods in ActiveRecord::QueryMethods.
+    #
+    # This method will also take multiple parameters:
+    #
+    #   >> Model.select(:field, :other_field, :and_one_more)
+    #   => [#<Model field: "value", other_field: "value", and_one_more: "value">]
+    #
+    # Any attributes that do not have fields retrieved by a select
+    # will return `nil` when the getter method for that attribute is used:
+    #
+    #   >> Model.select(:field).first.other_field
+    #   => nil
     def select(value = Proc.new)
       if block_given?
         to_a.select {|*block_args| value.call(*block_args) }
diff --git a/activerecord/lib/active_record/serializers/xml_serializer.rb b/activerecord/lib/active_record/serializers/xml_serializer.rb
index cbfa1ad609..0e7f57aa43 100644
--- a/activerecord/lib/active_record/serializers/xml_serializer.rb
+++ b/activerecord/lib/active_record/serializers/xml_serializer.rb
@@ -179,7 +179,7 @@ module ActiveRecord #:nodoc:
   class XmlSerializer < ActiveModel::Serializers::Xml::Serializer #:nodoc:
     def initialize(*args)
       super
-      options[:except] |= Array.wrap(@serializable.class.inheritance_column)
+      options[:except] = Array.wrap(options[:except]) | Array.wrap(@serializable.class.inheritance_column)
     end
 
     class Attribute < ActiveModel::Serializers::Xml::Serializer::Attribute #:nodoc: