Rails Cache Sweeper

Question

I'm trying to implement a Cache Sweeper which would filter a specific controller action.

class ProductsController < ActionController  
    caches_action :index  
    cache_sweeper :product_sweeper  

    def index 
        @products = Product.all 
    end 

    def update_some_state
      #... do some stuff which doesn't trigger a product save, but invalidates cache
    end
end 

Sweeper Class:

class ProductSweeper < ActionController::Caching::Sweeper
    observe Product

    #expire fragment after model update
    def after_save
       expire_fragment('all_available_products')   
    end

    #expire different cache after controller method modifying state is called.
    def after_update_some_state
        expire_action(:controller => 'products', :action => 'index') 
    end
end

The ActiveRecord callback 'after_save' will work fine, but the callback on the controller action 'after_update_some_state' never seems to be called.

Answer 1

I think your sweeper should look like this:

class ProductSweeper < ActionController::Caching::Sweeper
  observe Product

  def after_save(product)
     expire_cache(product)
  end

  def after_destroy(product)
    expire_cache(product)
  end

  private

  def expire_cache(product)
    expire_fragment('all_available_products')
    expire_page(:controller => 'products', :action => 'index')
  end 

after_index isn't a callback unless you define it.

In the controller you should specify those actions in which the sweeper should be triggered, in a restful way those actions should be create, update, destroy, so your controller declaration should look like:

class ProductsController < ActionController  
  caches_action :index  
  cache_sweeper :product_sweeper, :only => [:create, :update, :destroy]  

  def index 
    @products = Product.all 
  end 

  def create
    @product = Product.new(params[:product])

     if @product.save # triggers the sweeper.
       # do something
     else
       # do something else
     end
   end

  # update and stuff ...
end 

I hope it helps you!

Answer 2

Looks like I was just missing the controller name when trying to get the callbacks for controller actions working. My Sweeper should be:

class ProductSweeper < ActionController::Caching::Sweeper
    observe Product

    #expire fragment after model update
    def after_save
       expire_fragment('all_available_products')   
    end

    #expire different cache after controller method modifying state is called.
    def after_products_update_some_state
        expire_action(:controller => 'products', :action => 'index') 
    end

    #can also use before:
    def before_products_update_some_state
        #do something before. 
    end
end