How to cache tags with acts_as_taggable_on?

Question

I have model with tag context:

class Product < ActiveRecord::Base
  acts_as_taggable_on :categories
end

I'm trying to initialize tags caching:

class AddCachedCategoryListToProducts < ActiveRecord::Migration
  def self.up
    add_column :products,  :cached_category_list, :string
    Product.reset_column_information
    products = Product.all
    products.each { |p| p.save_cached_tag_list }
  end
end

But cached_category_list does not initializing. What I'm doing wrong? Does anybody can use caching with this gem (my version is 2.0.6)?

Rid

Answer 1

If you are using this in combination with owned tags, that might be the problem. Looking at the code of the gem, it seems that the caching of owned tags isn't support

Hope this helps,

Best, J

Pity

Answer 2

Well, today I had the same problem. I finally solved it, and my migration cached the desired tags. The problem with your migration was two-fold:

1. The ActsAsTaggable code which sets up caching needs to run again after the column information is reset. Otherwise, the caching methods are not created (see https://github.com/mbleigh/acts-as-taggable-on/blob/v2.0.6/lib/acts_as_taggable_on/acts_as_taggable_on/cache.rb)

2. The method you are calling, save_cached_tag_list, does NOT automatically save the record, as it is installed as a before_save hook, and it doesn't want to create an infinite loop. So you must call save.

So, try replacing your migration with the following, and it should work:

class AddCachedCategoryListToProducts < ActiveRecord::Migration
  def self.up
    add_column :products,  :cached_category_list, :string
    Product.reset_column_information
    # next line makes ActsAsTaggableOn see the new column and create cache methods
    ActsAsTaggableOn::Taggable::Cache.included(Product)
    Product.find_each(:batch_size => 1000) do |p|
      p.category_list # it seems you need to do this first to generate the list
      p.save! # you were missing the save line!
    end    
  end
end

That should do it.

Jaclyn

There is no need for p.save_cached_tag_list as that will be called by the before_save hook. – Arthralgia

@MichaelHale yes, I believe you are correct from looking at the code. I'll edit my answer – Jaclyn

Does this, from now on, perform caching on all items? Or do I have to run this every now and then? – Swoosh

How does this work? When does the cache expire? Are all of the tags for product being stored directly on the model table itself? As a string? What if this string gets really large (say the products have 30000 tags?) Or is it being stored per product (a product's tags are stored directly in the row itself). When does it expire? – Forfend