Question

我想做一些非常类似于GAE在Python中提供的留言簿示例。

但是允许一个用户多次签名，我希望每个提交都覆盖当前用户的任何预先存在的提交。

我无法弄清楚如何编辑此示例以使其发挥作用。

import cgi
import datetime
import urllib
import wsgiref.handlers

from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app


class Greeting(db.Model):
"""Models an individual Guestbook entry with an author, content, and date."""
author = db.StringProperty()
content = db.StringProperty(multiline=True)
date = db.DateTimeProperty(auto_now_add=True)


def guestbook_key(guestbook_name=None):
"""Constructs a Datastore key for a Guestbook entity with guestbook_name."""
return db.Key.from_path('Guestbook', guestbook_name or 'default_guestbook')


class MainPage(webapp.RequestHandler):
def get(self):
self.response.out.write('<html><body>')
guestbook_name=self.request.get('guestbook_name')

# Ancestor Queries, as shown here, are strongly consistent with the High
# Replication Datastore. Queries that span entity groups are eventually
# consistent. If we omitted the ancestor from this query there would be a
# slight chance that Greeting that had just been written would not show up
# in a query.
greetings = db.GqlQuery("SELECT * "
                        "FROM Greeting "
                        "WHERE ANCESTOR IS :1 "
                        "ORDER BY date DESC LIMIT 10",
                        guestbook_key(guestbook_name))

for greeting in greetings:
  if greeting.author:
    self.response.out.write(
        '<b>%s</b> wrote:' % greeting.author)
  else:
    self.response.out.write('An anonymous person wrote:')
  self.response.out.write('<blockquote>%s</blockquote>' %
                          cgi.escape(greeting.content))

self.response.out.write("""
      <form action="/sign?%s" method="post">
        <div><textarea name="content" rows="3" cols="60"></textarea></div>
        <div><input type="submit" value="Sign Guestbook"></div>
      </form>
      <hr>
      <form>Guestbook name: <input value="%s" name="guestbook_name">
      <input type="submit" value="switch"></form>
    </body>
  </html>""" % (urllib.urlencode({'guestbook_name': guestbook_name}),
                      cgi.escape(guestbook_name)))


class Guestbook(webapp.RequestHandler):
def post(self):
# We set the same parent key on the 'Greeting' to ensure each greeting is in
# the same entity group. Queries across the single entity group will be
# consistent. However, the write rate to a single entity group should
# be limited to ~1/second.
guestbook_name = self.request.get('guestbook_name')
greeting = Greeting(parent=guestbook_key(guestbook_name))

if users.get_current_user():
  greeting.author = users.get_current_user().nickname()

greeting.content = self.request.get('content')
greeting.put()
self.redirect('/?' + urllib.urlencode({'guestbook_name': guestbook_name}))


application = webapp.WSGIApplication([
('/', MainPage),
('/sign', Guestbook)
], debug=True)


def main():
run_wsgi_app(application)


if __name__ == '__main__':
main()

Answer 1

最简单的方法是修改post类的Guestbook方法，以便它检查当前用户的现有帖子并更新它（如果存在）。

class Guestbook(webapp.RequestHandler):
  def post(self):
    guestbook_name = self.request.get('guestbook_name')
    user = users.get_current_user()
    nickname = None
    if user:
      nickname = user.nickname()
      greeting = Greeting.gql('WHERE author = :1 AND ANCESTOR IS :2',
          nickname, guestbook_key(guestbook_name)).get()
    if not greeting:
      greeting = Greeting(parent=guestbook_key(guestbook_name))
      greeting.author = nickname

    greeting.content = self.request.get('content')
    greeting.put()
    self.redirect('/?' + urllib.urlencode({'guestbook_name': guestbook_name}))

使用python for GAE覆盖数据存储区 - 访客留言示例

1 个答案: