google app engine - How can I modify the property of ndb model through a webapp2 handler in python -

i have python file , html file interact each other through jinja2 environment in manner similar 1 in this tutorial.

the following code controls interaction between html file , python file:

 class mainpage(webapp2.requesthandler):      def get(self):         submission_query = submission.query().order(-submission.score)         submissions = submission_query.fetch(10)          template_values = {             'submission' : submission,             'submissions' : submissions,         }          template = jinja_environment.get_template('index.html')         self.response.write(template.render(template_values))  app = webapp2.wsgiapplication([     ('/', mainpage),     ('/create', createsubmmission),     ('/voteup', voteup), ], debug=true) 

i have ndb model follows:

class submission(ndb.model):     username = ndb.stringproperty()     placename = ndb.stringproperty()     link = ndb.stringproperty()     score = ndb.integerproperty() 

i have html form create new submission follows:

<form action="/create" method="post">     add new location: <br>     name:<div><textarea name="username" rows="2" cols="60"></textarea></div>     placename:<div><textarea name="placename" rows="2" cols="60"></textarea></div>     url:<div><textarea name="link" rows="2" cols="60"></textarea></div>     <div><input type="submit" value="post"></div> </form> 

using request handler:

class createsubmmission(webapp2.requesthandler):     def post(self):         submission = submission()         submission.username = self.request.get('username')         submission.placename = self.request.get('placename')         submission.link = self.request.get('link')         submission.score = 0         submission.put()         self.redirect('/') 

i have section in html prints out each submission along button upvoting it:

{% submission in submissions %}     <p>         {{submission.username}} posted:         <strong><a href="{{submission.link}}">{{submission.placename}}</a></strong> <br>         score:{{submission.score}}<br>           <!--vote button-->         <form action="/voteup?submission={{submission}}" method="post">             <div><input type="submit" value="voteup"></div>         </form>     </p><br><br> {% endfor %} 

the upvoting handled following python class:

class voteup(webapp2.requesthandler):     def post(self):         submission = self.request.get('submission')         submission_key = submission.put()         the_submission = submission_key.get()         the_submission.score +=1         the_submission.put()         self.redirect('/') 

when pressing button, value of respective submission's score attribute should increase one.

the code implemented on website sunlit-hook-91816.appspot.com. can seen on site, pressing upvote button generates following error:

file "/base/data/home/apps/s~sunlit-hook-91816/1.383863233180213164/guestbook.py", line 52, in post     submission_key = submission.put() attributeerror: 'str' object has no attribute 'put' 

it appears voteup class somehow unable modify value of submission.score.

i using information found here can't figure out how correctly apply problem. can tell me of way make voteup class modify submission.score?

you're using submission object can passed along between html/python code can't, must add reference in form , dereference in server.

do in vote form:

<form action="/voteup?submission={{submission.key.urlsafe()}}" method="post">     <div><input type="submit" value="voteup"></div> </form> 

we're getting key of submission in format safe http transport, can arrive server unaltered.

now when processing vote, can recreate key , correct object:

class voteup(webapp2.requesthandler):     def post(self):         submission = self.request.get('submission')         submission_key = ndb.key(urlsafe=submission)         the_submission = submission_key.get()         the_submission.score +=1         the_submission.put()         self.redirect('/') 

as can see we're recreating key based on formatted string printed in form.

another way make better use input in form:

<form action="/voteup" method="post">     <input name="submission" type="hidden" value="{{submission.key.urlsafe()}}">     <div><input type="submit" value="voteup"></div> </form> 

your code work same way, find easier read , maintain.