tornado 模板中如何使用datetime.datime.strptime函数?报错

大家好，今天遇到一个问题！

就是在tornado模板中需要转换日期字符串的格式！

例如，收到的字符串是'2015-10-11'，我需要转换成'Oct 11, 2015'

我用的是strptime和strftime两个函数！

具体如下：

datetime.datetime.strptime('2015-10-11', "%Y-%m-%d").strftime("%b %d, %Y")

<time class="entry-date">{{ datetime.datetime.strptime(passage.mtime, "%Y-%m-%d ").strptime("%b %d, %Y") }}</time>

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tornado-4.3.dev1-py2.7-linux-x86_64.egg/tornado/web.py", line 1411, in _execute
    result = method(*self.path_args, **self.path_kwargs)
  File "./blog.py", line 87, in get
    self.render("index.html", aside=True, passages=passages)
  File "/usr/local/lib/python2.7/dist-packages/tornado-4.3.dev1-py2.7-linux-x86_64.egg/tornado/web.py", line 701, in render
    html = self.render_string(template_name, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/tornado-4.3.dev1-py2.7-linux-x86_64.egg/tornado/web.py", line 808, in render_string
    return t.generate(**namespace)
  File "/usr/local/lib/python2.7/dist-packages/tornado-4.3.dev1-py2.7-linux-x86_64.egg/tornado/template.py", line 345, in generate
    return execute()
  File "index_html.generated.py", line 82, in _tt_execute
    _tt_tmp = datetime.datetime.strptime(passage.mtime, "%Y-%m-%d %H:%M:%S").strptime("%b %d, %Y")  # index.html:16 (via base.html:56)
TypeError: must be string, not datetime.datetime