Ruby on Rails counter cache error

Question

I get the error Unknown key(s): counter_cache when trying to implement a counter cache column in my RoR app.

I implemented the model associations in this question: Model association question

Here's my migration:

class AddVideoVotesCountToVideos < ActiveRecord::Migration
  def self.up
    add_column :videos, :video_votes_count, :integer, :default => 0

    Video.reset_column_information
    Video.find(:all).each do |p|
      p.update_attributes :videos_votes_count, p.video_votes.length
    end
  end

  def self.down
    remove_column :videos, :video_votes_count
  end
end

However, after watching http://media.railscasts.com/videos/023_counter_cache_column.mov I thought that maybe I had to move :counter_cache => true into the VideoVote model after belongs_to :video. However, when I do that, I get the error:

wrong number of arguments (2 for 1)

What am I doing wrong?

fl00r · Accepted Answer · 2011-03-17T19:34:46.703

4

update_attribute not update_attribteS

p.update_attribute :videos_votes_count, p.video_votes.length

or with update_attributes:

p.update_attributes( :video_votes_count => p.video_votes.length )

UPD 1

:counter_cache => true should be at the VideoVote class:

class VideoVote < ActiveRecord::Base
  belongs_to :user
  belongs_to :video, :counter_cache => true
end

edited Mar 17 '11 at 19:34

answered Mar 17 '11 at 19:22

fl00r

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still get the first error... where should `:counter_cache => true` go? – Justin Meltzer Mar 17 '11 at 19:28
ok, now I get this error: `undefined method 'videos_votes_count=' for #` – Justin Meltzer Mar 17 '11 at 19:37
you use `update_attributes` or `update_attribute`? Also you can temprory remove `counter_cache => true` because it obviously locks field – fl00r Mar 17 '11 at 19:40
What method do you use, which one `update_attributes` or `update_attribute` ? :) and remove `counter_cache => true` for a while, do your migrate and return it back :) – fl00r Mar 17 '11 at 19:42
ahh ok yeah, that solved it, I needed to take out counter_cache, migrate, and then return it back... thanks! – Justin Meltzer Mar 17 '11 at 19:45

score 3 · Answer 2 · answered Apr 27 '11 at 23:03

3

To do counter_caching,you need to run the migration first that fills in the count columns BEFORE you include the counter_cache statement in the model. Once in the model, the columns are read only.

answered Apr 27 '11 at 23:03

Rajive Jain

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stereoscott · Answer 3 · 2013-09-16T08:55:44.263

2

To avoid read-only errors while running this migration, you should use reset_counters:

Video.find_each do |video|
  Video.reset_counters video.id, :video_votes
end

edited Sep 16 '13 at 08:55

answered Aug 07 '12 at 05:35

stereoscott

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The second argument to the `reset_counters` method needs to be the name of the association, not the name of the counter_cache column, so it should be: `Video.reset_counters video.id, :video_votes` – Andrea Singh Apr 17 '13 at 23:57
`reset_counters` is now deprecated – ahnbizcad Sep 15 '14 at 17:27
1

@gwho I think it's still there... https://github.com/rails/rails/blob/master/activerecord/lib/active_record/counter_cache.rb#L20 – stereoscott Sep 15 '14 at 21:14

score 0 · Answer 4 · answered Jul 27 '12 at 19:33

0

Rewriting Rajive Jain's solution :

Remove :counter_cache => true statement from the model file.

Rerun the migration : rake db:migrate

Add the counter_cache statement in your model : :counter_cache => true

answered Jul 27 '12 at 19:33

Justin D.

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Ruby on Rails counter cache error

4 Answers4