我正在尝试使用用户输入的网址来收集该网址的标题，说明，root_url，方案和主机。
现在，我在调用MetaInspector时收到此错误：
NoMethodError - undefined method `normalize' for nil:NilClass:
这里将非常感谢帮助。我尝试了很多事情而没有任何结论。我错过了什么？
这是我的代码：
我点击链接#news view ..
日志
NoMethodError - undefined method `normalize' for nil:NilClass:
metainspector (5.2.1) lib/meta_inspector/url.rb:83:in `normalized'
metainspector (5.2.1) lib/meta_inspector/url.rb:50:in `url='
metainspector (5.2.1) lib/meta_inspector/url.rb:12:in `initialize'
metainspector (5.2.1) lib/meta_inspector/document.rb:31:in `initialize'
metainspector (5.2.1) lib/meta_inspector.rb:20:in `new'
app/services/get_meta.rb:11:in `new_record'
app/controllers/links_controller.rb:8:in `create'
actionpack (4.2.6) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (4.2.6) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.6) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.6) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.6) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.6) lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
activesupport (4.2.6) lib/active_support/callbacks.rb:505:in `call'
activesupport (4.2.6) lib/active_support/callbacks.rb:92:in `__run_callbacks__'
activesupport (4.2.6) lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
activesupport (4.2.6) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.6) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.6) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.6) lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
activesupport (4.2.6) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.6) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.6) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.6) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.6) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.6) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.6) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.6) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.6) lib/action_controller/metal.rb:196:in `dispatch'
actionpack (4.2.6) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.6) lib/action_controller/metal.rb:237:in `block in action'
actionpack (4.2.6) lib/action_dispatch/routing/route_set.rb:74:in `dispatch'
actionpack (4.2.6) lib/action_dispatch/routing/route_set.rb:43:in `serve'
actionpack (4.2.6) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.6) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.6) lib/action_dispatch/routing/route_set.rb:817:in `call'
omniauth (1.3.1) lib/omniauth/strategy.rb:186:in `call!'
omniauth (1.3.1) lib/omniauth/strategy.rb:164:in `call'
omniauth (1.3.1) lib/omniauth/builder.rb:63:in `call'
rack (1.6.4) lib/rack/etag.rb:24:in `call'
rack (1.6.4) lib/rack/conditionalget.rb:38:in `call'
rack (1.6.4) lib/rack/head.rb:13:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/flash.rb:260:in `call'
rack (1.6.4) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.4) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.6) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.6) lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
activerecord (4.2.6) lib/active_record/migration.rb:377:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.6) lib/active_support/callbacks.rb:88:in `__run_callbacks__'
activesupport (4.2.6) lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
activesupport (4.2.6) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.6) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
better_errors (2.1.1) lib/better_errors/middleware.rb:84:in `protected_app_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:79:in `better_errors_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:57:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.6) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.6) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.6) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.6) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.6) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.6) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.4) lib/rack/runtime.rb:18:in `call'
activesupport (4.2.6) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
actionpack (4.2.6) lib/action_dispatch/middleware/static.rb:120:in `call'
rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
railties (4.2.6) lib/rails/engine.rb:518:in `call'
railties (4.2.6) lib/rails/application.rb:165:in `call'
rack (1.6.4) lib/rack/content_length.rb:15:in `call'
puma (3.4.0) lib/puma/configuration.rb:224:in `call'
puma (3.4.0) lib/puma/server.rb:569:in `handle_request'
puma (3.4.0) lib/puma/server.rb:406:in `process_client'
puma (3.4.0) lib/puma/server.rb:271:in `block in run'
puma (3.4.0) lib/puma/thread_pool.rb:114:in `block in spawn_thread'
我有两个模型：Link和Domain
型号：
class Domain < ActiveRecord::Base
has_many :links
end
class Link < ActiveRecord::Base
has_one :domain
end
表格
# Table name: links
#
# id :integer not null, primary key
# url :string
# created_at :datetime not null
# updated_at :datetime not null
#
# Table name: domains
#
# id :integer not null, primary key
# root_url :string
# scheme :string
# host :string
# created_at :datetime not null
# updated_at :datetime not null
链接控制器
class LinksController < ApplicationController
def new
@link = Link.new
end
def create
@link = GetMeta.new(params[:url]).new_record
redirect_to root_url
end
private
def link_params
params.require(:link).permit(:url, :created_at, :updated_at)
end
end
服务对象：Get_Meta.rb
class GetMeta
include ActiveModel::Model
def initialize(url)
@url = url
end
def new_record
#https://github.com/jaimeiniesta/metainspector
page = MetaInspector.new(@url)
Link.create! do |link|
link.url = page.url
link.title = page.title
link.description = page.description
link.domain.build(root_url: page.root, scheme: page.scheme, host: page.host)
end
end
end
答案 0 :(得分：1)
好的，所以堆栈跟踪中的相关行是这两个：
NoMethodError - undefined method `normalize' for nil:NilClass:
metainspector (5.2.1) lib/meta_inspector/url.rb:83:in `normalized'
从消息中，你已经可以猜到metainspector假定不会有的东西是零。但是，让我们跟着堆栈跟踪来确定。
你在评论中列出的内容（感谢BTW，这真是一个好主意！）项目在这里：https://github.com/jaimeiniesta/metainspector
如果单击该文件，则查找列出的文件：lib/meta_inspector/url.rb:83
并按照上面的说明查看第83行，你得到这个：
# Normalize url to deal with characters that should be encoded,
# add trailing slash, convert to downcase...
def normalized(url)
Addressable::URI.parse(url).normalize.to_s
所以...在metainspector中规范化，期望实际上有一个网址......并且当它为零时吓坏了。这样就可以确认问题是没有url传递给metainspector。
这意味着你需要在传递网址之前检查一下......或者至少弄清楚为什么你没有通过他的网址...我认为我可以在这里找到原因：
这一行表明params很可能通过：{:link => {:url => 'some_url'}}
params.require(:link).permit(:url, :created_at, :updated_at)
params[:link][:url] 访问的
但您使用该网址的代码是：
@link = GetMeta.new(params[:url]).new_record
所以我将上面的用法改为以下，你应该好好去
@link = GetMeta.new(params[:link][:url]).new_record