title: Bootstrap typeahead avoid other value
body: <p>i still try in rails 3.2 to use bootstrap typeahead, it works fine, but how can i avoid users to type anything in text field.<br>
  I code looks like this  </p>
  
  <pre><code>&lt;%= text_field_tag(:text, "", :data =&gt; {:provide =&gt; "typeahead", :items=&gt;"4", :source=&gt;'["Swiss","German","English"]'}) %&gt;  
  </code></pre>
  
  <p>users may only type Swiss, German and English in the text field, but not for example Chinese.<br>
  How can i validate the value in text field?</p>