input_handler.rb

require 'rss/1.0'
require 'rss/2.0'
require 'hpricot'
require 'open-uri'

# This is an abstract InputHandler. 
#
# InputHandlers fetch, parse and store articles from and RSS feed. 
# All InputHandlers should extend this class.
class InputHandler
  
  attr_accessor :feed_name, :feed_url
  
  # Return very generic info about the Feed. 
  def info
    "#{@feed_name} (#{@feed_url})"
  end
  
  # Run the InputHanlder
  def run
    rss = retrieve_rss
    
    unless rss.nil? || rss.items.nil?
      rss.items.each { |item| process_item(item) }
    end
  end
  
  def retrieve_rss
    begin
      content = ""
      open(@feed_url) { |s| content = s.read }
      return RSS::Parser.parse(content, false)
    rescue
      puts "There was an error retrieving the RSS feed."
      return nil
    end
  end
  
  def process_item(item)
        
    article_attributes = {
      :title        => item.title,
      :author       => item.author,
      :category     => item.category.content,
      :body         => item.description,
      :link         => item.link,

      # item.pubDate reports to be of type Time. Time.parse(item.pubDate.to_s) works fine. 
      # Using item.pubDate directly (as shown) this results in the exception seen in trace.txt
      # when saving. 
      # When replacing 'item.pubDate' with 'Time.parse(item.pubDate.to_s)' things work fine (as expected)

      :published_at => item.pubDate,

      :feed_url     => @feed_url,
      :feed_name    => @feed_name
    }
    
    article = Article.new(article_attributes)
    article.save
  rescue
    puts "Error while processing item."    
  end
  
  # Run all InputHandlers
  def self.run_all
    handlers_dir = (defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/app/handlers" : "app/handlers")
    
    # Find all input handlers, load them and run them.
    Dir["#{handlers_dir}/**/*_input_handler.rb"].each do |handler|
      # Load the handler file
      require handler
      
      # Find the class_name (conventions are great!)
      extract = /^#{Regexp.quote(handlers_dir)}\/?(.*).rb$/
      handler_class = handler.sub(extract, '\1')
      
      # Create an instance of the inputhandler and call 'run'.
      handler_instance = handler_class.camelize.constantize.new
      handler_instance.run
    end
    
  end
end

trace.txt

>> InputHandler.run_all
ArgumentError: wrong number of arguments (1 for 0)
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/time_with_zone.rb:146:in `to_s'
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/time_with_zone.rb:146:in `to_s'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/abstract/quoting.rb:61:in `quoted_date'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/abstract/quoting.rb:29:in `quote'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/mysql_adapter.rb:223:in `quote'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2817:in `attributes_with_quotes'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2808:in `each'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2808:in `attributes_with_quotes'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2723:in `create_without_callbacks'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/callbacks.rb:237:in `create_without_timestamps'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/timestamp.rb:29:in `create'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2699:in `create_or_update_without_callbacks'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/callbacks.rb:222:in `create_or_update'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:2383:in `save_without_validation'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/validations.rb:1009:in `save_without_dirty'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/dirty.rb:79:in `save_without_transactions'
... 1 levels...
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:179:in `with_transaction_returning_status'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/abstract/database_statements.rb:66:in `transaction'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:129:in `transaction'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:138:in `transaction'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:178:in `with_transaction_returning_status'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:146:in `save'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:158:in `rollback_active_record_state!'
	from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/transactions.rb:146:in `save'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:64:in `process_item'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:25:in `run'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:25:in `each'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:25:in `run'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:91:in `run_all'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:81:in `each'
	from /Users/ariejan/rails/rsstank/lib/input_handler.rb:81:in `run_all'
>> 

tweakers_input_handler.rb

# This just set the feed_url and feed_name, the rest is InputHandler.

class TweakersInputHandler < InputHandler
  
  # Set +@feed_url+ and +@feed_name+ for later reference
  def initialize
    @feed_url = "http://feedproxy.google.com/tweakers/mixed"
    @feed_name = "Tweakers.net"
  end
  
end