Raise error when using write_attribute with a non-existent attribute.

Previously we would just silently write the attribute. This can lead to
subtle bugs (for example, see the change in AutosaveAssociation where a
through association would wrongly gain an attribute.

Also, ensuring that we never gain any new attributes after
initialization will allow me to reduce our dependence on method_missing.

4 files changed, 15 insertions, 6 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index 5621b44c8c..e9cdb130db 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -28,12 +28,16 @@ module ActiveRecord
       # for fixnum and float columns are turned into +nil+.
       def write_attribute(attr_name, value)
         attr_name = attr_name.to_s
-        attr_name = self.class.primary_key if attr_name == 'id'
+        attr_name = self.class.primary_key if attr_name == 'id' && self.class.primary_key
         @attributes_cache.delete(attr_name)
-        if (column = column_for_attribute(attr_name)) && column.number?
+        column = column_for_attribute(attr_name)
+
+        if column && column.number?
           @attributes[attr_name] = convert_number_column_value(value)
-        else
+        elsif column || @attributes.has_key?(attr_name)
           @attributes[attr_name] = value
+        else
+          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
         end
       end
       alias_method :raw_write_attribute, :write_attribute
diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index 085fdba639..056170d82a 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -370,7 +370,10 @@ module ActiveRecord
         else
           key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
           if autosave != false && (new_record? || record.new_record? || record[reflection.foreign_key] != key || autosave)
-            record[reflection.foreign_key] = key
+            unless reflection.through_reflection
+              record[reflection.foreign_key] = key
+            end
+
             saved = record.save(:validate => !autosave)
             raise ActiveRecord::Rollback if !saved && autosave
             saved
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 2dac9ea0fb..5e65e46a7d 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -314,7 +314,7 @@ module ActiveRecord
 
       new_id = self.class.unscoped.insert attributes_values
 
-      self.id ||= new_id
+      self.id ||= new_id if self.class.primary_key
 
       IdentityMap.add(self) if IdentityMap.enabled?
       @new_record = false
diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index cccac6ffd7..4d5e469a7f 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -48,7 +48,9 @@ module ActiveRecord
         current_time = current_time_from_proper_timezone
 
         all_timestamp_attributes.each do |column|
-          write_attribute(column.to_s, current_time) if respond_to?(column) && self.send(column).nil?
+          if respond_to?(column) && respond_to?("#{column}=") && self.send(column).nil?
+            write_attribute(column.to_s, current_time)
+          end
         end
       end