大家好我有一点问题我收到错误：
"File "C:\Users\kokki\Desktop\gb1\main.py", line 36, in get
self.response.out.write(greeting.date.strftime('<b>posted: %d, %h %Y </b><br>'))
ValueError: Invalid format string"
任何人都可以帮忙吗？继承人代码：
import cgi
import datetime
import wsgiref.handlers
from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.ext import webapp
class Greeting(db.Model):
author = db.UserProperty()
content = db.StringProperty(multiline=True)
date = db.DateTimeProperty(auto_now_add=True)
class MainPage(webapp.RequestHandler):
def get(self):
self.response.out.write('<html><body>')
greetings = db.GqlQuery("SELECT * FROM Greeting ORDER BY date DESC LIMIT 10")
for greeting in greetings:
self.response.out.write(greeting.date.strftime('<b>posted: %d, %h %Y </b><br>'))
if greeting.author:
self.response.out.write('<b>%s</b> wrote:' % greeting.author.nickname())
else:
self.response.out.write('An anonymous person wrote:')
self.response.out.write('<blockquote>%s</blockquote>' %
cgi.escape(greeting.content))
# Write the submission form and the footer of the page
self.response.out.write("""
<form action="/sign" method="post">
<div><textarea name="content" rows="3" cols="60"></textarea></div>
<div><input type="submit" value="Sign Guestbook"></div>
</form>
</body>
</html>""")
class Guestbook(webapp.RequestHandler):
def post(self):
greeting = Greeting()
if users.get_current_user():
greeting.author = users.get_current_user()
greeting.content = self.request.get('content')
greeting.put()
self.redirect('/')
application = webapp.WSGIApplication([
('/', MainPage),
('/sign', Guestbook)
], debug=True)
def main():
wsgiref.handlers.CGIHandler().run(application)
if __name__ == '__main__':
main()