def update_attribute(name, value)
      name = name.to_s
      raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
      send("#{name}=", value)
      save(:validate => false)
    end
def update_attribute(name, value)
      name = name.to_s
      raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
      send("#{name}=", value)
      save(:validate => false)
    end
Updates a single attribute and saves the record.
 This is especially useful for boolean flags on existing records. Also note that

 * Validation is skipped.
 * Callbacks are invoked.
 * updated_at/updated_on column is updated if that column is available.
 * Updates all the attributes that are dirty in this object.