通过heroku查看博客帖子时出现Rails错误

Question

我的rails应用程序的一部分显示了博客帖子。索引博客页面在heroku中显示此错误：

2014-10-23T08:19:39.662420+00:00 app[web.1]: Completed 500 Internal Server Error in 55ms
2014-10-23T08:19:39.662025+00:00 app[web.1]:   Rendered posts/_post.html.erb (26.6ms)
2014-10-23T08:19:39.604425+00:00 app[web.1]: Started GET "/posts" for 14.203.244.3 at 2014-10-23 08:19:39 +0000
2014-10-23T08:19:39.607283+00:00 app[web.1]: Processing by PostsController#index as HTML
2014-10-23T08:19:39.662204+00:00 app[web.1]:   Rendered posts/index.html.haml within layouts/application (30.9ms)
2014-10-23T08:19:40.175104+00:00 app[web.1]: ** [Airbrake] Failure: Net::HTTPUnauthorized
2014-10-23T08:19:40.177411+00:00 app[web.1]: 
2014-10-23T08:19:40.177423+00:00 app[web.1]:     25: 
2014-10-23T08:19:40.177425+00:00 app[web.1]:   app/views/posts/_post.html.erb:22:in `block in _app_views_posts__post_html_erb__2896285066252331072_70186208567180'
2014-10-23T08:19:40.177426+00:00 app[web.1]:   app/views/posts/_post.html.erb:22:in `map'
2014-10-23T08:19:40.177421+00:00 app[web.1]:     23:       </ul>
2014-10-23T08:19:40.177427+00:00 app[web.1]:   app/views/posts/_post.html.erb:22:in `_app_views_posts__post_html_erb__2896285066252331072_70186208567180'
2014-10-23T08:19:40.177422+00:00 app[web.1]:     24:     </div>
2014-10-23T08:19:40.177429+00:00 app[web.1]:   app/views/posts/index.html.haml:8:in `_app_views_posts_index_html_haml___4113059566178405055_70186208452460'
2014-10-23T08:19:40.177418+00:00 app[web.1]:     21:       <ul class="tags">
2014-10-23T08:19:40.177430+00:00 app[web.1]: 
2014-10-23T08:19:40.177416+00:00 app[web.1]:     19: 
2014-10-23T08:19:40.177431+00:00 app[web.1]: 
2014-10-23T08:19:40.177414+00:00 app[web.1]: ActionView::Template::Error (No route matches {:tag=>""} missing required keys: [:tag]):
2014-10-23T08:19:40.177417+00:00 app[web.1]:     20:     <div class="tags_wrapper">
2014-10-23T08:19:40.177420+00:00 app[web.1]:     22:         <li><%= raw post.tags.map(&:name).map { |t| link_to t, tag_path(t)}.join(' ')  %></li>
2014-10-23T08:19:40.178906+00:00 heroku[router]: at=info method=GET path="/posts" host=www.guidetobe.co.uk request_id=570f17d3-4f6b-4db0-9d13-da69bc1ff49b fwd="14.203.244.3" dyno=web.1 connect=1ms service=574ms status=500 bytes=1575
2014-10-23T08:19:40.980832+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=www.guidetobe.co.uk request_id=767bc8e9-11e7-445f-8f78-d44a8c22ff0c fwd="14.203.244.3" dyno=web.1 connect=3ms service=1ms status=200 bytes=241

posts.rb模型是：

class Post < ActiveRecord::Base
  extend FriendlyId
  friendly_id :title, use: :slugged

  validates :title, presence: true
  validates :body, presence: true
  validates :author, presence: true
  validates :published_on, presence: true

  has_many :taggings
  has_many :tags, through: :taggings

  # Tagging
  def self.tagged_with(name)
    Tag.find_by_name!(name).posts
  end

  def self.tag_counts
    Tag.select("tags.id, tags.name, count(taggings.tag_id) as count").
      joins(:taggings).group("taggings.tag_id, tags.id, tags.name")
  end

  def tag_list
    tags.map(&:name).join(", ")
  end

  def tag_list=(names)
    self.tags = names.split(",").map do |n|
      Tag.where(name: n.strip).first_or_create!
    end
  end

end

posts / index.html.haml是：

- content_for :head, auto_discovery_link_tag(:atom, posts_url(format: "atom"))

.preview_posts_wrapper
  .blog_posts_left_column
    %h1{style: 'font-size: 20px; color: #6a6a6a;'} My blog
    .rss_icon
      = link_to image_tag('feed-icon-28x28.png'), posts_url(format: 'atom')
    = render @posts
  .blog_posts_right_column
    %h3{style: 'font-size: 16px; color: #6a6a6a;'} Tag Cloud
    .tag_cloud_wrapper
      - tag_cloud Post.tag_counts, %w[s m l] do |tag, css_class|
        = link_to tag.name, tag_path(tag.name), class: css_class

博客页面在我的localhost中运行正常。我不确定为什么它不适用于heroku？