rake 任务中 open-uri 出现 404 错误...是什么原因造成的？

Question

我有一个 rake 任务，它从 API 获取 JSON 数据，解析它，并将其保存到数据库：

task :embedly => :environment do
  require 'json'
  require 'uri'
  require 'open-uri'

  Video.all.each do |video|
    json_stream = open("http://api.embed.ly/1/oembed?key=08b652e6b3ea11e0ae3f4040d3dc5c07&url=#{video.video_url}&maxwidth=525")
    ruby_hash = JSON.parse(json_stream.read)
    thumbnail_url = ruby_hash['thumbnail_url']
    embed_code = ruby_hash['html']
    video.update_attributes(:thumbnail_url => thumbnail_url, :embed_code => embed_code)
  end  
end

当我运行 rake 任务时，我在堆栈跟踪中收到此错误，但我不知道是什么原因导致的：

rake aborted!
404 Not Found
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:277:in `open_http'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:616:in `buffer_open'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:164:in `open_loop'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:162:in `catch'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:162:in `open_loop'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:132:in `open_uri'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:518:in `open'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:30:in `open'
/rubyprograms/dreamstill/lib/tasks/tasks.rake:16
/rubyprograms/dreamstill/lib/tasks/tasks.rake:15:in `each'
/rubyprograms/dreamstill/lib/tasks/tasks.rake:15
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `call'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:597:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'

关于问题所在以及如何解决？

Answer 1

如果指定的资源（视频/图片）不存在，embed.ly api 将返回 404。 OpenURI 将此作为异常处理。要捕获错误，您可以执行以下操作：

task :embedly => :environment do
  require 'json'
  require 'uri'
  require 'open-uri'

  Video.all.each do |video|
    begin
      json_stream = open("http://api.embed.ly/1/oembed?key=08b652e6b3ea11e0ae3f4040d3dc5c07&url=#{video.video_url}&maxwidth=525")
      ruby_hash = JSON.parse(json_stream.read)
      thumbnail_url = ruby_hash['thumbnail_url']
      embed_code = ruby_hash['html']
      video.update_attributes(:thumbnail_url => thumbnail_url, :embed_code => embed_code)
    rescue OpenURI::HTTPError => ex
      puts "Handle missing video here"
    end 
  end  
end

您还可以在运行任务之前检查视频/网址是否有效。

Answer 2

您没有对 video.url 进行 URL 编码：

json_stream = open("...url=#{video.video_url}...")

因此您可能生成了一个损坏的 URL，而 api.embed.ly 告诉您它找不到它。例如，如果 video.video_url 为 http://ab?c=d&e=f，则将看到 e=f作为 http://api.embed.ly/1/oembed 的参数，而不是传递给 http://ab。

您可能想这样做：

require 'cgi'
#...
json_stream = open("...url=#{CGI.escape(video.video_url)}...")