Question

I’m trying to add a counter_cache to my tag table

when I run my migration to add the column it aborts (but not before adding the column)
I don’t understand it, and although it makes the column, it’s going stop any future migrations. How do i fix this?

==  AddCountToTags: migrating =================================================
-- add_column(:tags, :reports_count, :integer, {:default=>0})
   -> 0.1405s
rake aborted!
An error has occurred, all later migrations canceled:

wrong number of arguments (0 for 1)

The trace:

/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/counter_cache.rb:17:in `reset_counters'
/Dropbox/Shared/repair/db/migrate/20120120234938_add_count_to_tags.rb:5:in `up'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:314:in `block in migrate'
/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/benchmark.rb:295:in `measure'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:314:in `migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:397:in `migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:539:in `block (2 levels) in migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:615:in `call'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:615:in `ddl_transaction'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:538:in `block in migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:525:in `each'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:525:in `migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:435:in `up'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/migration.rb:417:in `migrate'
/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/railties/databases.rake:151:in `block (2 levels) in <top (required)>'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `call'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `block in execute'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `each'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `execute'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:158:in `block in invoke_with_call_chain'
/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/task.rb:144:in `invoke'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:116:in `invoke_task'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block (2 levels) in top_level'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `each'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block in top_level'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:88:in `top_level'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:66:in `block in run'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>'
/.rvm/gems/ruby-1.9.2-p290/bin/rake:19:in `load'
/.rvm/gems/ruby-1.9.2-p290/bin/rake:19:in `<main>'

migration file:

class AddCountToTags < ActiveRecord::Migration
  def self.up
    add_column :tags, :reports_count, :integer, :default => 0

    Tag.reset_counters
    Tag.find(:all).each do |t|
      t.update_attribute(:reports_count, t.reports.length)
    end
  end

  def self.down
    remove_column :tags, :reports_count
  end
end

relevant models:

class TagAssignment < ActiveRecord::Base
  belongs_to :tag, :counter_cache => :reports_count
  belongs_to :report
end

class Tag < ActiveRecord::Base
  has_many :tag_assignments, :dependent => :destroy
  has_many :reports, :through => :tag_assignments
end

Answer 1

From what I see here you need to pass an id to reset_counters.

it seems that what you want to do should be (untested) done by:

Tag.find_each do |t|
  Tag.reset_counters(t.id, :reports) 
end