reset_counters is failing on exisitng and new projects - ruby-on-rails

Question

Ok..I hope I am doing something dumb (which is usually the case). I have been humming along, adding cache counters to my existing project, when all of the sudden reset_counters failed for pretty much everything. I checked out an old copy when things were working, and it still failed, so I started on a brand new demo project.
I assume this is my error because it suddenly stopped working..and I don't see anyone else having similar issues.
I am using ruby 1.9.3-p392, and rails 3.2.12.
The counters themselves work on both existing and new projects. you just can't use reset_counters.
So here is the problem on a brand new project:
class Post < ActiveRecord::Base
attr_accessible :name
has_many :comments
end
class Comment < ActiveRecord::Base
attr_accessible :name
belongs_to :post, :counter_cache => true
end
here we can see the counters increment:
irb(main):073:0* post = Post.create(:name => 'i am a post')
(0.3ms) BEGIN
SQL (0.4ms) INSERT INTO `posts` (`comments_count`, `created_at`, `name`, `updated_at`) VALUES (0, '2013-03-14 19:56:53', 'i am a post', '2013-03-14 19:56:53')
(0.5ms) COMMIT
=> #<Post id: 3, name: "i am a post", created_at: "2013-03-14 19:56:53", updated_at: "2013-03-14 19:56:53", comments_count: 0>
irb(main):074:0> post.comments << Comment.new(:name => 'i am a comment')
(0.2ms) BEGIN
SQL (0.3ms) INSERT INTO `comments` (`created_at`, `name`, `post_id`, `updated_at`) VALUES ('2013-03-14 19:57:18', 'i am a comment', 3, '2013-03-14 19:57:18')
Post Load (0.3ms) SELECT `posts`.* FROM `posts` WHERE `posts`.`id` = 3 LIMIT 1
SQL (0.3ms) UPDATE `posts` SET `comments_count` = COALESCE(`comments_count`, 0) + 1 WHERE `posts`.`id` = 3
(0.4ms) COMMIT
Comment Load (0.2ms) SELECT `comments`.* FROM `comments` WHERE `comments`.`post_id` = 3
=> [#<Comment id: 3, name: "i am a comment", post_id: 3, created_at: "2013-03-14 19:57:18", updated_at: "2013-03-14 19:57:18">]
irb(main):075:0> post = Post.find(3)
Post Load (0.5ms) SELECT `posts`.* FROM `posts` WHERE `posts`.`id` = 3 LIMIT 1
=> #<Post id: 3, name: "i am a post", created_at: "2013-03-14 19:56:53", updated_at: "2013-03-14 19:56:53", comments_count: 1>
running the code I get:
irb(main):001:0> Post.reset_counters(1,:comments_count)
Post Load (0.5ms) SELECT `posts`.* FROM `posts` WHERE `posts`.`id` = 1 LIMIT 1
NoMethodError: undefined method `options' for nil:NilClass
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/activerecord-3.2.12/lib/active_record/counter_cache.rb:22:in `block in reset_counters'
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/activerecord-3.2.12/lib/active_record/counter_cache.rb:19:in `each'
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/activerecord-3.2.12/lib/active_record/counter_cache.rb:19:in `reset_counters'
from (irb):1
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/railties-3.2.12/lib/rails/commands/console.rb:47:in `start'
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/railties-3.2.12/lib/rails/commands/console.rb:8:in `start'
from /Users/charles/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/railties-3.2.12/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

Answer 1

You're almost entirely correct. The parameter in reset_counters though should be the object name, not the column name. So in your case you want to:
1.9.3-p392 :005 > Post.reset_counters(1, :comments)
Post Load (0.3ms) SELECT "posts".* FROM "posts" WHERE "posts"."id" = ? LIMIT 1 [["id", 1]]
(0.1ms) SELECT COUNT(*) FROM "comments" WHERE "comments"."post_id" = 1
(2.3ms) UPDATE "posts" SET "comments_count" = 1 WHERE "posts"."id" = 1
=> true