如何使用 Rails 缓存来存储 Nokogiri 对象？

Question

我正在使用 Rails 5 使用 Rails 缓存来存储 Nokogiri 对象。

我在 config/initializers/cache.rb:

创建了这个

$cache = ActiveSupport::Cache::MemoryStore.new

我想像这样存储文档：

$cache.fetch(url) {
  result = get_content(url, headers, follow_redirects)
}

但我收到此错误：

Error during processing: (TypeError) no _dump_data is defined for class Nokogiri::HTML::Document
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:671:in `dump'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:671:in `dup_value!'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache/memory_store.rb:128:in `write_entry'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:398:in `block in write'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:562:in `block in instrument'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/notifications.rb:166:in `instrument'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:562:in `instrument'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:396:in `write'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:596:in `save_block_result_to_cache'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.2/lib/active_support/cache.rb:300:in `fetch'
/Users/davea/Documents/workspace/myproject/app/helpers/webpage_helper.rb:116:in `get_cached_content'
/Users/davea/Documents/workspace/myproject/app/helpers/webpage_helper.rb:73:in `get_url'
/Users/davea/Documents/workspace/myproject/app/services/abstract_my_object_finder_service.rb:29:in `process_data'
/Users/davea/Documents/workspace/myproject/app/services/run_crawlers_service.rb:26:in `block (2 levels) in run_all_crawlers'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:348:in `run_task'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:337:in `block (3 levels) in create_worker'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:320:in `loop'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:320:in `block (2 levels) in create_worker'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:319:in `catch'
/Users/davea/.rvm/gems/ruby-2.4.0/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:319:in `block in create_worker'

我需要做什么才能将这些对象存储在缓存中？

Answer 1

将 xml 存储为字符串，而不是对象，并在将它们从缓存中取出后进行解析。

编辑：回复评论

改为缓存

nokogiri_object.to_xml

Edit2：回复评论。沿着这条线的东西。如果您需要更具体的帮助，您将需要 post 更多代码。

nokogiri_object = Nokogiri::XML(cache.fetch('xml_doc'))

编辑 3：对 'Thanks but what is the code for "Store serialized object in cache"? I thought the body of the "$cache.fetch(url) {" would take care of storing and then retrieving things?'

的回应

cache.write('url', xml_or_serialized_nokogiri_string)

Answer 2

用户 Nokogiri 的序列化功能：

$cache = ActiveSupport::Cache::MemoryStore.new 
noko_object = Nokogiri::HTML::Document.new

serial = noko_object.serialize
$cache.write(url, serial)
// Serialized Nokogiri document is now in store at the URL key.
result = $cache.read(url)

noko_object = Nokogiri::HTML::Document.new(result)
// noko_object is now the original document again :)

Check out the documentation here for more information.

如何使用 Rails 缓存来存储 Nokogiri 对象？

How do I use a Rails cache to store Nokogiri objects?

ruby

caching

ruby-on-rails

nokogiri