问Flask:无法接收HTML表单发布数据

EN

  <form class="form-horizontal" action="/" method="POST">
    <div class="control-group">
      <label class="control-label" for="email">Email</label>
      <div class="controls">
        <input type="text" id="email" placeholder="Email">
      </div>
    </div>
    <div class="control-group">
      <label class="control-label" for="password">Password</label>
      <div class="controls">
        <input type="password" id="password" placeholder="Password">
      </div>
    </div>
    <div class="control-group">
      <div class="controls">
        <button type="submit" class="btn">Sign In</button>
      </div>
    </div>
  </form>

   def post(self):
        print 'data :', request.form

data : ImmutableMultiDict([])

def post(self):
        print 'data :', request.json

data : None