Ruby on Rails： url_for :back 导致 back_url 的 NoMethodError

Question

我正在尝试使用 url_for(:back) 创建一个重定向，以便在用户登录时返回到上一页。

当用户自己进入登录页面时，我已经成功地工作了。但是，当用户由于访问需要用户身份验证的页面而被重定向到登录页面时，重定向会将用户返回到他/她尝试访问但权限不足的页面。

我正在尝试修改我的登录控制器操作以正确处理重定向。我的计划是在发生强制重定向时使用查询字符串参数“redirect”。在控制器中，如果该参数存在，则使用该 URL；否则，使用 url_for(:back)，或者如果这不起作用（由于缺少 HTTP_REFERER），则用户将被重定向到站点的主页。

这里是实现这个逻辑的代码sn-p：

if params[:redirect]
  @url = params[:redirect]
else
  @url = url_for :back
  @url ||= url_for :controller => "home", :action => "index"
end

我得到的错误是：

UsersController#login 中的 NoMethodError

未定义的方法 `back_url' 用于#

RAILS_ROOT：[模糊]
应用程序跟踪 |框架跟踪 |全跟踪

供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__'
供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url'
供应商/rails/actionpack/lib/action_controller/base.rb:628:in `url_for'
app/controllers/users_controller.rb:16:in `login'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:76:in `进程'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `同步'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:在“进程”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `每个'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `初始化'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:282:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `each'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:128:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/command.rb:212:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:281

供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__'
供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url'
供应商/rails/actionpack/lib/action_controller/base.rb:628:in `url_for'
供应商/rails/actionpack/lib/action_controller/base.rb:1256:in `send'
供应商/rails/actionpack/lib/action_controller/base.rb:1256:in `perform_action_without_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:617:in `call_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark'
供应商/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
供应商/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
供应商/rails/actionpack/lib/action_controller/rescue.rb:136:in `perform_action_without_caching'
供应商/rails/actionpack/lib/action_controller/caching/sql_cache.rb:13:in `perform_action'
供应商/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache'
供应商/rails/activerecord/lib/active_record/query_cache.rb:8:in `cache'
供应商/rails/actionpack/lib/action_controller/caching/sql_cache.rb:12:in `perform_action'
供应商/rails/actionpack/lib/action_controller/base.rb:524:in `send'
供应商/rails/actionpack/lib/action_controller/base.rb:524:in `process_without_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:606:in `process_without_session_management_support'
供应商/rails/actionpack/lib/action_controller/session_management.rb:134:in `process'
供应商/rails/actionpack/lib/action_controller/base.rb:392：在“进程”中
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:184:in `handle_request'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:112:in `dispatch_unlocked'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:125:in `dispatch'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:124：在“同步”中
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `dispatch'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:134:in `dispatch_cgi'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:41:in `dispatch'
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load_without_new_constant_marking'
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load'
供应商/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load'
供应商/rails/railties/lib/commands/servers/mongrel.rb:64
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
供应商/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
供应商/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
供应商/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
供应商/rails/railties/lib/commands/server.rb:49
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
脚本/服务器：3

供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `__send__'
供应商/rails/actionpack/lib/action_controller/polymorphic_routes.rb:112:in `polymorphic_url'
供应商/rails/actionpack/lib/action_controller/base.rb:628:in `url_for'
app/controllers/users_controller.rb:16:in `login'
供应商/rails/actionpack/lib/action_controller/base.rb:1256:in `send'
供应商/rails/actionpack/lib/action_controller/base.rb:1256:in `perform_action_without_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:617:in `call_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark'
供应商/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
供应商/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
供应商/rails/actionpack/lib/action_controller/rescue.rb:136:in `perform_action_without_caching'
供应商/rails/actionpack/lib/action_controller/caching/sql_cache.rb:13:in `perform_action'
供应商/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache'
供应商/rails/activerecord/lib/active_record/query_cache.rb:8:in `cache'
供应商/rails/actionpack/lib/action_controller/caching/sql_cache.rb:12:in `perform_action'
供应商/rails/actionpack/lib/action_controller/base.rb:524:in `send'
供应商/rails/actionpack/lib/action_controller/base.rb:524:in `process_without_filters'
供应商/rails/actionpack/lib/action_controller/filters.rb:606:in `process_without_session_management_support'
供应商/rails/actionpack/lib/action_controller/session_management.rb:134:in `process'
供应商/rails/actionpack/lib/action_controller/base.rb:392：在“进程”中
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:184:in `handle_request'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:112:in `dispatch_unlocked'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:125:in `dispatch'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:124：在“同步”中
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:124:in `dispatch'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:134:in `dispatch_cgi'
供应商/rails/actionpack/lib/action_controller/dispatcher.rb:41:in `dispatch'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:76:in `进程'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:in `同步'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/rails.rb:74:在“进程”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `每个'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `初始化'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:282:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:in `each'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/configurator.rb:281:在“运行”中
/var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:128:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/command.rb:212:in `run'
/var/lib/gems/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:281
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load_without_new_constant_marking'
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load'
供应商/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
供应商/rails/activesupport/lib/active_support/dependencies.rb:142:in `load'
供应商/rails/railties/lib/commands/servers/mongrel.rb:64
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
供应商/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
供应商/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
供应商/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
供应商/rails/railties/lib/commands/server.rb:49
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
脚本/服务器：3

要求

参数：

没有

显示会话转储

---
：用户：
:csrf_id: 2927cca61bbbe97218362b5bcdb74c0f
flash: !map:ActionController::Flash::FlashHash {}


回复

标题：

{"内容类型"=>"",
 “饼干”=>[],
 "缓存控制"=>"无缓存"}

请记住，我之前已经让它工作了——url_for(:back) 在我添加这个逻辑之前就知道如何正确操作。

提前感谢您的任何想法！

Answer 1

就我而言，有时 :back 指向我想离开的同一个地方，因此会发生循环。我的解决方案是： application_controller 中的方法

def new_loc
  url = request.referer.to_s
  url == "" || url == request.url ? root_path : url
end

在你的控制器中

@url = params[:redirect] ? params[:redirect] : new_loc

或者在我的情况下

redirect_to new_loc

就是这样。我在 Rails 5 上

Answer 2

您正在尝试在控制器中使用视图辅助方法。您期望的行为位于 ActionView::Helpers::UrlHelper 中，但您调用的方法位于 ActionController::Base 中。不幸的是，这两种方法的名称相同，功能也非常相似，但并不完全相同。

为了快速修复，ActionController::Base 设置了一个@template 变量，该变量可以访问所有 ActionView 助手。尝试从该对象调用url_for，如下所示：

if params[:redirect]
  @url = params[:redirect]
else
  @url = @template.url_for :back
  @url ||= url_for :controller => "home", :action => "index"
end

不过，我不确定这是否是“正确”的做法。如果 Rails 开发人员希望我们随意使用 @template 变量，他们会做更多宣传。

另一种获取原始引荐来源网址（您要查找的 :back）的方法是使用 request 方法：

if params[:redirect]
  @url = params[:redirect]
else
  @url = request.env["HTTP_REFERER"]
  @url ||= url_for :controller => "home", :action => "index"
end