title: Rails undefined method `html_safe' for Formtastic
body: <p>I am using Formtastic and on a form I have:</p>
  
  <pre><code>&lt;%= f.input :open_date, :as =&gt; :string, :input_html =&gt; {:class =&gt; 'datepicker'}, :start_date =&gt; Date.today, label: 'OPEN' %&gt;
  </code></pre>
  
  <p>Then I validate the field with</p>
  
  <pre><code>validates :open_date, presence: true
  </code></pre>
  
  <p>If I submit the form with empty field it returns:</p>
  
  <pre><code>NoMethodError in Clients#create
  
  Completed 500 Internal Server Error in 44ms (ActiveRecord: 5.7ms)
  
  
  
  ActionView::Template::Error (undefined method `html_safe' for Formtastic::Util:Module
  Did you mean?  html_safe?):
       6:   &lt;div class="row"&gt;
       7: 
       8:     &lt;div class="col-sm-3"&gt;
       9:       &lt;%= f.input :open_date, :as =&gt; :string, :input_html =&gt; {:class =&gt; 'datepicker'}, :start_date =&gt; Date.today, label: 'OPEN' %&gt;
      10:     &lt;/div&gt;
      11: 
      12:     &lt;div class="col-sm-3"&gt;
  </code></pre>
  
  <p>I can't find any other way to call datepicker other  than with</p>
  
  <pre><code>:input_html =&gt; {:class =&gt; 'datepicker'}
  </code></pre>
  
  <p>How can I fix the issue?</p>