title: SQLAlchemy/WTForms: set default selected value for QuerySelectField
body: <p>This [example][1] to set up a form with WTForms and SQLAlchemy in Flask and add a QuerySelectField to the form works. I am not using <code>flask.ext.sqlalchemy</code>, my code:</p>
  
  <pre><code>ContentForm = model_form(Content, base_class=Form)
  ContentForm.author = QuerySelectField('Author', get_label="name")
  myform = ContentForm(request.form, content)
  myform.author.query = query_get_all(Authors)
  </code></pre>
  
  <p>Now I want to <strong>set the default value of the QuerySelectField's selectlist</strong>. </p>
  
  <p>Tried passing a <code>default</code> kwarg in QuerySelectField and setting <code>selected</code> attributes. Nothing worked. Am I missing something obvious? Can someone help?</p>