# Two alias\_method\_chain calls: first works second doesn't **URL:** \ **Category:** Rails\ **Created:** [April 2, 2008, 6:24am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635 "2008-04-02T06:24:19Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 2, 2008, 6:24am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/1 "2008-04-02T06:24:19Z")
In the example code in this Pastie [Parked at Loopia](http://pastie.caboo.se/129000), I’m observing behavior I can’t explain. I’m making two calls to alias\_method\_chain to extend create\_table and drop\_table. The create\_table alias chain works as expected. While debugging the drop\_table\_with alias chained method is never entered. Thanks in advance for your help. ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 2, 2008, 4:10pm UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/2 "2008-04-02T16:10:46Z")
Any chance it’s as simple as the placement of your requires? ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 3, 2008, 4:35am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/3 "2008-04-03T04:35:14Z")
On Apr 2, 10:09 am, AndyV [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > Thanks in advance for your help. > > I don’t think so. Both create\_table\_with and drop\_table\_with are in > > the same file which is included from environment.rb’s last line ActiveRecord::ConnectionAdapters::SchemaStatements.send(:include, AuditingTables::ActiveRecord::ConnectionAdapters::SchemaStatements) ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 3, 2008, 5:09am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/4 "2008-04-03T05:09:19Z")
Okay, I haven’t dug deep into this but I can give you a few pointers. First of all, the alias\_method\_chain is being done to a module so your methods only do stuff when they are actually included in a class. With that in mind, what happens here? module Failure def failure\_type “everything is fine” end def failure\_type\_with\_foo puts “I intercepted it!” failure\_type\_without\_foo end alias\_method\_chain :failure\_type, :foo end class SomethingThatFails include Failure def failure\_type “epic” end end SomethingThatFails.new.failure\_type #=\> “epic” This could be an explanation. Regards, Trevor On 4/2/08, Jobu [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > drop\_table\_with alias chained method is never entered. > > > ## – Trevor S. [http://somethinglearned.com](http://somethinglearned.com) ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 7, 2008, 1:58am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/5 "2008-04-07T01:58:02Z")
On Apr 3, 10:14 am, AndyV [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > thought they might provide something helpful. > drop\_table\_with\_auditing\_table doesn’t require the code in the > requires. Also, that function’s not even being entered. ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 3, 2008, 4:15pm UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/6 "2008-04-03T16:15:47Z")
Sorry I should have been more specific. Your pastie shows: line 13: def drop\_table\_with\_auditing\_table line 20 require ‘rails\_generator’ line 21 require ‘rails\_generator/scripts/generate’ line 23 def create\_table\_with\_auditing\_table Since the code that works follows the requires at lines 20 and 21 I thought they might provide something helpful. On a side note, depending on what your audit code needs to accomplish “acts\_as\_versioned” might be a good fit. ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 7, 2008, 2:01am UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/7 "2008-04-07T02:01:33Z")
Thanks for looking, but I believe I’ve tried what you suggest. 1. I believe the extension to the module is included in the extended module globally, because of the following line in environment.rb ActiveRecord::ConnectionAdapters::SchemaStatements.send(:include,AuditingTables::ActiveRecord::ConnectionAdapters::SchemaStatements) 2. I’ve used a debugger and seen that the failure\_type\_with\_foo (my drop\_table\_with\_auditing\_table) in your example is never entered. However my create\_table\_with\_auditing\_table, which is defined and included in an identical manner is always entered. Could something be overriding or blocking my extension of drop\_table? ---
**Author:** ![jobu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ea5d25/32.png) [@jobu](https://www.ruby-forum.com/u/jobu)\ **Post date:** [April 7, 2008, 5:14pm UTC](https://www.ruby-forum.com/t/two-alias-method-chain-calls-first-works-second-doesnt/133635/8 "2008-04-07T17:14:42Z")
On 4/6/08, Jobu [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 1. I’ve used a debugger and seen that the failure\_type\_with\_foo (my > drop\_table\_with\_auditing\_table) in your example is never entered. > However my create\_table\_with\_auditing\_table, which is defined and > included in an identical manner is always entered. > > Could something be overriding or blocking my extension of drop\_table? Yeah, that’s the whole point of what I showed you. No amount of monkeypatching in the Failure module can compensate for the fact that the SomethingThatFails class defines its own failure\_type() method. Try to figure out the type of the object you are calling drop\_table() on, then look at the rails source to see whether that class in question happens to define its own drop\_table method. If you’re impatient you can always just search for “def drop\_table” in the rails source. Chances are, you’re going to have to monkeypatch that class rather than SchemaStatements. HTH Trevor ## – Trevor S. [http://somethinglearned.com](http://somethinglearned.com)