Overriding a single Rails core file (batches.rb)

Hi everyone,

I’m trying to find a way to implement a diff I found into my
application (Tickets - Ruby on Rails - rails
2137-allow-find_batches-to-use-order-limit-and-offset). It is
imperative that I use find_in_batches as well as passing an :order
option to the function. Certain rows need to be processed before
others, and because of the size of the table I can’t do them all at

Now, my question is, how could I do this with the least amount of
fuss? I don’t want to edit the batches.rb in my Rails installation, as
I then would have to do the same on servers and other workstations. I
also don’t particularly want to freeze Rails. I’ve tried just slapping
a new batches.rb into /vendor/rails/activerecord/lib/active_record/,
hoping that that would override just that file, but it doesn’t seem to

Any help would be appreciated!

Best regards,



I will most likely go with option 2. Can I just copy-paste the
modified methods as per the diff into any of those directories
(obviously with “module ActiveRecord” and “module Batches” at the
top)? Do I need to adhere to a specific naming scheme for the file?

Apologies for all the questions. I’m still (re-)learning Rails.

Best regards,


Since it’s an ActiveRecord module that gets included into AR::Base,
you either need to:

  1. (Sneaky) Load your own Batches module when AR wants to autoload it
    (active_record.rb:51) - override Module#autoload to ‘listen’ for the
    Batches module, and substitute your version (located in /lib or
    something) instead. You’ll have to do this before Rails loads AR,
    though, so put it in /config/preinitializer.rb.

  2. (More sane) Monkey-patch the changed methods into AR::B through a
    file you include in /lib, /config/initializers or through your own
    plugin. You would probably be overriding #find_in_batches,
    #sort_batch_rows! and #select_batch_ids.

  3. Freeze rails, replace the file. This is the simplest, and least
    error-prone, though upgrading and patching Rails may be trickier.


On Thu, Sep 24, 2009 at 4:47 PM, Sebastian von Conrad

Nevermind, figured it out.

Thanks again!

  • Sebastian

On Sep 25, 10:12 am, Sebastian von Conrad