title: NoMethodError in UsersController#show / undefined method `key?' for nil:NilClass
body: <p>I've encountered an unexpected error while following Michael Hartl's <em>Rails Tutorial</em>. It had been smooth sailing.</p>
  
  <p>I first saw that I was getting a different "Action Controller: Exception caught" error than the Tutorial following the completion of <a href="http://ruby.railstutorial.org/chapters/sign-up.html#code-users_resource" rel="nofollow noreferrer">Hartl's Listing 7.3</a>. </p>
  
  <p>Specifically, when trying to reach /users/1, I get:</p>
  
  <blockquote>
    <p>NoMethodError in UsersController#show</p>
    
    <p>undefined method `key?' for nil:NilClass</p>
  </blockquote>
  
  <p>I continued on through Listing 7.5 - adding a view for for a User's show action and then adding the show action to the Users controller - which resolved the error Hartl was getting, but these steps didn't resolve my error.</p>
  
  <p>Based on <a href="https://stackoverflow.com/questions/9440325/rails-3-2-undefined-method-key-for-nilnilclass">this question</a>, I've verified that my app/models/user.rb is free of typos: after scouring it for typos, I copied &amp; pasted Hartl's code into my file for good measure.</p>
  
  <p>Any guidance on where else to look for typos/issues would be much appreciated.</p>
  
  <p><strong>EDIT 1:</strong> As requested, the UsersController#show method:</p>
  
  <pre><code>def show
    @user = User.find(params[:id])
  end
  </code></pre>
  
  <p><strong>EDIT 2:</strong> Full trace:</p>
  
  <blockquote>
    <p>actionpack (3.2.8) lib/action_controller/metal/hide_actions.rb:36:in `visible_action?'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal/hide_actions.rb:18:in `method_for_action'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal/implicit_render.rb:14:in `method_for_action'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal/compatibility.rb:61:in `method_for_action'</p>
    
    <p>actionpack (3.2.8) lib/abstract_controller/base.rb:115:in `process'</p>
    
    <p>actionpack (3.2.8) lib/abstract_controller/rendering.rb:45:in `process'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal.rb:203:in `dispatch'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'</p>
    
    <p>actionpack (3.2.8) lib/action_controller/metal.rb:246:in `block in action'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:73:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:36:in `call'</p>
    
    <p>journey (1.0.4) lib/journey/router.rb:68:in `block in call'</p>
    
    <p>journey (1.0.4) lib/journey/router.rb:56:in `each'</p>
    
    <p>journey (1.0.4) lib/journey/router.rb:56:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/routing/route_set.rb:600:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/etag.rb:23:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/conditionalget.rb:25:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/head.rb:14:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/params_parser.rb:21:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/flash.rb:242:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'</p>
    
    <p>rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/cookies.rb:339:in `call'</p>
    
    <p>activerecord (3.2.8) lib/active_record/query_cache.rb:64:in `call'</p>
    
    <p>activerecord (3.2.8) lib/active_record/connection_adapters/abstract/connection_pool.rb:473:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'</p>
    
    <p>activesupport (3.2.8) lib/active_support/callbacks.rb:405:in `_run__3560654018285941260__call__3098371293035639072__callbacks'</p>
    
    <p>activesupport (3.2.8) lib/active_support/callbacks.rb:405:in `__run_callback'</p>
    
    <p>activesupport (3.2.8) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'</p>
    
    <p>activesupport (3.2.8) lib/active_support/callbacks.rb:81:in `run_callbacks'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:27:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/reloader.rb:65:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'</p>
    
    <p>railties (3.2.8) lib/rails/rack/logger.rb:26:in `call_app'</p>
    
    <p>railties (3.2.8) lib/rails/rack/logger.rb:16:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/request_id.rb:22:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/runtime.rb:17:in `call'</p>
    
    <p>activesupport (3.2.8) lib/active_support/cache/strategy/local_cache.rb:72:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/lock.rb:15:in `call'</p>
    
    <p>actionpack (3.2.8) lib/action_dispatch/middleware/static.rb:62:in `call'</p>
    
    <p>railties (3.2.8) lib/rails/engine.rb:479:in `call'</p>
    
    <p>railties (3.2.8) lib/rails/application.rb:223:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/content_length.rb:14:in `call'</p>
    
    <p>railties (3.2.8) lib/rails/rack/log_tailer.rb:17:in `call'</p>
    
    <p>rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'</p>
    
    <p>/Users/aaronmacy/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'</p>
    
    <p>/Users/aaronmacy/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'</p>
    
    <p>/Users/aaronmacy/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'</p>
  </blockquote>
  
  <p><strong>EDIT 3:</strong> users_controller.rb:</p>
  
  <pre><code>class UsersController &lt; ApplicationController
  
    def show
      @user = User.find(params[:id])
    end
  
    def new
    end
  end
  </code></pre>
  
  <p>user.rb:</p>
  
  <pre><code>class User &lt; ActiveRecord::Base
    attr_accessible :name, :email, :password, :password_confirmation
    has_secure_password
  
    before_save { self.email.downcase! }
  
    validates :name, presence: true, length: { maximum: 50 }
    VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
    validates :email, presence:   true,
                      format:     { with: VALID_EMAIL_REGEX },
                      uniqueness: { case_sensitive: false }
    validates :password, presence: true, length: { minimum: 6 }
    validates :password_confirmation, presence: true
  end
  </code></pre>
  
  <p>routes.rb:</p>
  
  <pre><code>SampleApp::Application.routes.draw do
    resources :users
  
    root to: 'static_pages#home'
  
    match '/signup',  to: 'users#new'
  
    match '/help',    to: 'static_pages#help'
    match '/about',   to: 'static_pages#about'
    match '/contact', to: 'static_pages#contact'
  end
  </code></pre>