# How to add a method\_missing method into ActiveRecord **URL:** \ **Category:** Ruby\ **Created:** [December 13, 2006, 3:03am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193 "2006-12-13T03:03:27Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 3:03am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/1 "2006-12-13T03:03:27Z")
i want to write a plugin that support like following Book.search\_by\_author\_and\_description(keyword) i must hold method\_missing to dynamic find books but ActiveRecord already used method\_missing . how can i add onother method\_misng method ? ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 6:03am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/2 "2006-12-13T06:03:40Z")
I believe you can alias the original method\_missing, and then add a new method\_missing which calls the original except when your version is relevant. it would look something like this: alias :original\_method\_missing :method\_missing def method\_missing(\*args) case args when /normal stuff/ original\_method\_missing(args) when /new stuff/ # your code goes here end end (please bear in mind this is just a sketch.) – Giles B. [http://www.gilesgoatboy.org](http://www.gilesgoatboy.org) > **[Giles Bowkett](http://gilesbowkett.blogspot.com)** > > half-disavowed old blog. new blog at gilesbowkett.com [http://gilesgoatboy.blogspot.com](http://gilesgoatboy.blogspot.com) ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 6:15am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/3 "2006-12-13T06:15:41Z")
What Giles said, except: when /new stuff/: #your code else original\_method\_missing(\*args,&blk) Probably makes more sense. ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 8:31am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/4 "2006-12-13T08:31:44Z")
On 13 Dec 2006, at 14:47, ao tianlong wrote: > 11 end > missingmy method missintest.rb:9:in `method_missing': stack level too deep (SystemStackError) from test.rb:9:in`method\_missing’ > from test.rb:14 > > any idia? You are calling a missing method from within your new method\_missing. Infinite recursion ensues. The following seems to work: irb(main):001:0\> class Book irb(main):002:1\> def method\_missing(mtd,\*arg,&blk) irb(main):003:2\> puts “Original” irb(main):004:2\> end irb(main):005:1\> alias :original :method\_missing irb(main):006:1\> def method\_missing(mtd,\*arg,&blk) irb(main):007:2\> puts “New” irb(main):008:2\> original(mtd,\*arg,&blk) irb(main):009:2\> end irb(main):010:1\> end =\> nil irb(main):011:0\> Book.new.test New Original =\> nil Alex G. Bioinformatics Center Kyoto University ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 8:55am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/5 "2006-12-13T08:55:45Z")
thank you i find the error original\_method\_missing(method\_id,\*prams,&block) it’s misspelled \*params as prams thank you again. ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 6:47am UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/6 "2006-12-13T06:47:43Z")
1 class Book 2 def method\_missing(method\_id,\*params,&block) 3 print ‘original method missing’ 4 end 5 6 alias :original\_method\_missing :method\_missing 7 def method\_missing(method\_id,\*params,&block) 8 C(params[:comment])print ‘my method missing’ 9 original\_method\_missing(method\_id,\*prams,&block) 10 end 11 end 12 13 book = Book.new 14 book.tester its looks like work , but output is thod missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missingmy method missintest.rb:9:in `method_missing': stack level too deep (SystemStackError) from test.rb:9:in`method\_missing’ from test.rb:14 any idia? thank you for your help ---
**Author:** ![ao\_tianlong](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c89c15/32.png) [@ao\_tianlong](https://www.ruby-forum.com/u/ao_tianlong)\ **Post date:** [December 13, 2006, 8:45pm UTC](https://www.ruby-forum.com/t/how-to-add-a-method-missing-method-into-activerecord/79193/7 "2006-12-13T20:45:25Z")
ao tianlong wrote: > i want to write a plugin > that support like following > > Book.search\_by\_author\_and\_description(keyword) > i must hold method\_missing to dynamic find books > but ActiveRecord already used method\_missing . > how can i add onother method\_misng method ? You could alias the existing method\_missing, redefine it to capture the cases you are interested in and forward the rest on to the aliased method. Check out Module#alias\_method\_chain in Rails 1.2: > **[New in Rails: Module#alias\_method\_chain](https://rubyonrails.org/2006/4/26/new-in-rails-module-alias_method_chain)** > > Though not an outward facing feature, changeset 4276 introduces a nice method to DRY up and encapsulate the common pattern of aliasing a method so that you can build behavior on top of it.All over the internals of Rails you’ll find code like this in... Tom