title: Rails view, undefined method `empty?' for a datetime object
body: <p>So i was modifying my index view as to make it only render specific fields based on an instance variable named fields, but when i did this it worked just fine except for the datetime field that generates an error. example :<code>undefined method empty?' for Tue, 22 Nov 2016 23:01:00 +0000:DateTime</code> Here's the view code. </p>
  
  <pre><code>&lt;p id="notice"&gt;&lt;%= notice %&gt;&lt;/p&gt;
  
  &lt;h1&gt;Articles&lt;/h1&gt;
  
  &lt;table&gt;
    &lt;thead&gt;
      &lt;% @fields = ["headline", "content","date", "locale", "classification" ]  unless @fields.present? %&gt;
      &lt;tr&gt;
        &lt;% @fields.each do |field| %&gt;
          &lt;th&gt;&lt;%= "#{field.titleize}" %&gt;&lt;/th&gt;
        &lt;% end %&gt;
      &lt;/tr&gt;
    &lt;/thead&gt;
  
    &lt;tbody&gt;
      &lt;% @articles.each do |article| %&gt;
        &lt;tr&gt;
          &lt;% @fields.each do |field| %&gt;
          &lt;td&gt;&lt;%= simple_format article.send(field) %&gt;&lt;/td&gt;
          &lt;% end %&gt;
          &lt;td&gt;&lt;%= link_to 'Show', article %&gt;&lt;/td&gt;
          &lt;td&gt;&lt;%= link_to 'Edit', edit_article_path(article) %&gt;&lt;/td&gt;
          &lt;td&gt;&lt;%= link_to 'Destroy', article, method: :delete, data: { confirm: 'Are you sure?' } %&gt;&lt;/td&gt;
        &lt;/tr&gt;
      &lt;% end %&gt;
    &lt;/tbody&gt;
  &lt;/table&gt;
  
  &lt;br&gt;
  
  &lt;%= link_to 'New Article', new_article_path %&gt;
  </code></pre>
  
  <p>And here's the model code</p>
  
  <pre><code>class Article
    include Mongoid::Document
    validates :classification,
      :inclusion  =&gt; { :in =&gt; [ 'unclassified', 'medical', 'non medical'] }
    validates :headline, presence: true
    validates :content, presence: true
    field :headline, type: String
    field :content, type: String
    field :classification, type: String
    field :weak_classification, type: String
    field :locale, type: String
    field :date, type: DateTime
  end
  </code></pre>
  
  <p>How can i fix this issue?</p>