Google App Engine出现黑屏错误

Question

I am trying out this idea where there is a table of 'events' on a '/search' page and when a 'GO' button of an event is pressed, it will increment the 'RSVP' count of that event, and redirect back to '/search'. However, when I clicked on the 'GO' button in my application, it leads to a blank screen with url 'localhost:8080/rsvp'.

Finding it strange and wondering which part of my code is wrong. Here are some of the relevant parts of the code that I think is causing the error.

This is the code from the python file:

class RSVPItem(webapp2.RequestHandler):
    # increment RSVP count when GO button is clicked
    def post(self):
        itemkey = ndb.Key('Items', self.request.get('itemid'))
        item = itemkey.get()
        item.rsvp = item.rsvp + 1
        item.put()
        self.redirect('/search')

# Handler for the Search page
class Search(webapp2.RequestHandler):
    # Display search page
    def get(self):
        user = users.get_current_user()
        if user:  # signed in already
            # Retrieve items
            query = ndb.gql("SELECT * "
                            "FROM Items ")

            template_values = {
                'user_mail': users.get_current_user().email(),
                'logout': users.create_logout_url(self.request.host_url),
                'items': query,
            }
            template = jinja_environment.get_template('search.html')
            self.response.out.write(template.render(template_values))
        else:
            self.redirect(self.request.host_url)

app = webapp2.WSGIApplication([('/', MainPage),
                           ('/giftbook', MainPageUser),
                           ('/wishlist', WishList),
                           ('/deleteitem', DeleteItem),
                           ('/search', Search),
                           ('/rsvp', RSVPItem),
                           ('/display', Display),
                           ('/displaytag', Displaytag)],
                          debug=True)

This is from the html file for 'search.html'. Only showing the part I think is relevant.

<h4> Events List </h4>
<table class="table table-bordered table-striped">
    <thead>
    <tr>
        <th width="10%">Name</th>
        <th>Description</th>
        <th width = "10%">Link</th>
        <th width = "10%">Date</th>
        <th width = "10%">Type</th>
        <th width = "10%">RSVP</th>
        <th width = "10%">Rolling?</th>
    </tr>
    </thead>
    <tbody>
    {% for item in items %}
        <tr>
            <td>{{ item.event_name }} </td>
            <td>{{ item.description }}</td>
            <td>{{ item.event_link}}</td>
            <td>{{ item.date.strftime('%Y-%m-%d')  }}</td>
            <td>{{ item.event_type}}</td>
            <td>{{ item.rsvp }}
            <td>
                <form action="/rsvp" method="post">
                    <input type="hidden" name="itemid" value="{{ item.item_id }}">
                    <input type="submit" value="GO!">
                </form></td>
        </tr>
    {% endfor %}
    </tbody>
</table>

Answer 1

<form action="/rsvp" method="post"> sends them to /rsvp . Do you have a url handler for /rsvp ?

Make sure you cast the Key to an int :

itemkey = ndb.Key('Items', int(self.request.get('itemid')))

Instead of setting your own id item_id , just use the built-in Key :

<input type="hidden" name="itemid" value="{{ item.key.id() }}">

Check the logs to see if there are any errors.