Question

I’m trying to monkey patch an existing ActiveRecord Observer; specifically, IssueObserver from the code base of Redmine 1.0.4.

In a plugin’s init.rb, I have include the *patch.rb file:

require File.join(File.dirname(__FILE__), 'lib/issue_observer_patch.rb')
IssueObserver.send :include, IssueObserverPatch

This is done outside the Redmine::Plugin.register block.

The module does something like:

module IssueObserverPatch
  def self.included(base)
    base.send :alias_method_chain, :after_create, :audit
  end

  def after_create_with_audit(issue)
    after_create_without_audit(issue)
    issue.logger.info('***'*50)
    # Insert a new Audit instance.
  end
end

However, when I run the server (using script/server, which is using Mongrel), the patch seems to do nothing. The ***..*** string does not get logged when I create a new issue.

By changing the IssueObserver and including a sentence to log the after_create event, and then running the server and creating an issue; I can see this log, but not the log on after_create_with_audit method.

Is there any proper way to patch an ActiveRecord Observer?

Answer 1

It seems that Rails VM are loaded and unloaded on demand. So, changing the code on the init.rb to the following solves the problem:

config.to_prepare do
  IssueObserver.send :include, IssueObserverPatch
end

This makes this block of code to be execute per VM on production and per request on development.