Counter Cache Reset for Counters
When you want to implement counter cache, how to handle the counters for the old data? Generally you will add a migration which runs a script to update all the counts, unfortunately you wil get an error, because the column is readonly, you can't update this column in a normal way.
Model
class Post < ActiveRecord::Base
belongs_to :category, :counter_cache => :resources_count
end
Incorrect way
class InitializeResourcesCountForCategories < ActiveRecord::Migration
def up
Category.find_each do |cat|
cat.update_attribute(:resources_count => cat.posts.count)
end
end
end
You should be using User.reset_counters to do this
class InitializeResourcesCountForCategories < ActiveRecord::Migration
def up
Category.find_each do |cat|
Category.reset_counters(cat.id, :posts)
end
end
end