title: Rails simple-form datepicker how to add data-behaviour
body: <p>I have a Rails app using jquery-ui datePicker.</p>
  
  <p>Inside of a simple_form I have two fields. The first one is just a test field. The first one has datePicker working.  I'm trying to get "data-behaviour" into the simple_form f.input line.  But, I've got the wrong syntax.</p>
  
  <pre><code>&lt;input type="text" data-behaviour='datepicker' &gt;
  &lt;%= f.input :exp_date, :data-behaviour =&gt; 'datepicker', :as =&gt; :string, :label =&gt; 'Date', :input_html =&gt; {:value =&gt; Date.today.to_s} %&gt;
  </code></pre>
  
  <p>This is my jquery:</p>
  
  <pre><code>$(document).on "focus", "[data-behaviour~='datepicker']", (e) -&gt;
    $(this).datepicker
      format: "yyyy-mm-dd"
      weekStart: 1
      autoclose: true
  </code></pre>
  
  <p>How can I get the data-behavior='datepicker' into the f.input line?</p>
  
  <p>Thanks!</p>