Question

I have a before_save in my Message model defined like this:

   class Message < ActiveRecord::Base
     before_save lambda { foo(publisher); bar }
   end

When I do:

   my_message.update_attributes(:created_at => ...)

foo and bar are executed.

Sometimes, I would like to update message’s fields without executing foo and bar.

How could I update, for example, the created_at field (in the database) without executing foo and bar ?

Answer 1

In rails 3.1 you will use update_column.

Otherwise:

In general way, the most elegant way to bypass callbacks is the following:

class Message < ActiveRecord::Base
  cattr_accessor :skip_callbacks
  before_save lambda { foo(publisher); bar }, :unless => :skip_callbacks # let's say you do not want this callback to be triggered when you perform batch operations
end

Then, you can do:

Message.skip_callbacks = true # for multiple records
my_message.update_attributes(:created_at => ...)
Message.skip_callbacks = false # reset

Or, just for one record:

my_message.update_attributes(:created_at => ..., :skip_callbacks => true)

If you need it specifically for a Time attribute, then touch will do the trick as mentioned by @lucapette .