Someone

<html>
  <head>
    <title tal:content="template/title">The title</title>
  </head>
  <body>
    
<form method="get" action="">
<select>
 <option tal:repeat="person context/selectAll"
         tal:content="person/name"
         tal:attributes="value person/name; name string:a_name"
         >
         
 </option>
</select>
<input type="submit" />
</form>

<div tal:condition="request/a_name">
got a name
</div>



  </body>
</html>