callback executed like after_save but after transaction

rubyonrails-talk
1

I'm trying to add some code for my ActiveRecord class so that it is executed whenever an object is updated, this code is a seperate process that reads from the same table represented by my model class so when it runs it needs the database to be up to date.

In the following situation this is fine:

# MyModel def after_save   `/usr/local/bin/update_models -i #{self.id}` end

# controller action delete def delete   MyModel.find(params[:id]).update_attribute(:deleted_at, Time.now) # after_save is called when the table end

But in this situation:

# controller action new def new   MyModel.transaction do     newmodel = MyModel.new     othermodel = MyOtherModel.new     ... other code ...     newmodel.save!     othermodel.save!   end end

after_save gets called inside the transaction, and so the database is not up to date! I've looked into ActiveRecord::Observers but this also faces the same problem. Is there any way around this?

2

# Here is my idea for how this might be achieved, given no knowledge of how to accomplish it the rails way # comments / feedback / criticism welcomed # (note this is just a proof of concept not rails compatible code)

class ActiveRecord

  def self.transaction(&block)     Thread.current['after_commit_procs'] ||=     block.call

    Thread.current['after_commit_procs'].each do |proc|       proc.call     end   end

  def save     if self.respond_to?(:after_commit) then       Thread.current['after_commit_procs'] << self.method(:after_commit)     end     puts "Saving..."   end

end

class MyRecord < ActiveRecord

  def after_commit     puts "after_commit callback called!"   end end

MyRecord.transaction do   rec = MyRecord.new   puts "Before save"   rec.save   puts "After save, before commit" end puts "After commit"

# output: # Before save # Saving... # After save, before commit # after_commit callback called! # After commit

3

Thinking Sphinx defines an after_commit callback to run the indexer for delta indexes. It is based on this post:

   Eli Miller: Proper cache expiry with after_commit

You can check the actual code in lib/thinking_sphinx/active_record/ delta.rb.