title: ASP.NET MVC Adding Attribute "data-message" to Html.TextBoxFor
body: <p>Using MVC 4 I create a text box for a model property with the "data-message" attribute:</p>
  
  <pre><code>@Html.TextBoxFor(o =&gt; o.TradeOrder.Symbol, new {data-message="Required"})
  </code></pre>
  
  <p>However, I get the following error:</p>
  
  <blockquote>
    <p>Invalid anonymous type member declarator. Anonymous type members must
    be declared with a member assignment, simple name or member access.</p>
  </blockquote>