1 files changed, 15 insertions, 5 deletions
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index c77a3ac145..07499db9f0 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -10,7 +10,7 @@ module ActiveRecord
       module ClassMethods
         protected
           def define_method_attribute=(attr_name)
-            if attr_name =~ ActiveModel::AttributeMethods::COMPILABLE_REGEXP
+            if attr_name =~ ActiveModel::AttributeMethods::NAME_COMPILABLE_REGEXP
               generated_attribute_methods.module_eval("def #{attr_name}=(new_value); write_attribute('#{attr_name}', new_value); end", __FILE__, __LINE__)
             else
               generated_attribute_methods.send(:define_method, "#{attr_name}=") do |new_value|
@@ -24,12 +24,14 @@ 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?
-          @attributes[attr_name] = convert_number_column_value(value)
+        column = column_for_attribute(attr_name)
+
+        if column || @attributes.has_key?(attr_name)
+          @attributes[attr_name] = type_cast_attribute_for_write(column, value)
         else
-          @attributes[attr_name] = value
+          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
         end
       end
       alias_method :raw_write_attribute, :write_attribute
@@ -39,6 +41,14 @@ module ActiveRecord
         def attribute=(attribute_name, value)
           write_attribute(attribute_name, value)
         end
+
+        def type_cast_attribute_for_write(column, value)
+          if column && column.number?
+            convert_number_column_value(value)
+          else
+            value
+          end
+        end
     end
   end
 end