How to use AJAX with Google App Engine (Python)
I am completely novice at AJAX. I am familiar with HTML/CSS, jQuery and beginner at GAE and Python.
In an effort to understand how AJAX works, I would like to know how AJAX might be used (actual code) in this example below. Let's use a reddit-like example where vote ups/downs are ajaxified:
Here is the Story Kind:
class Story(ndb.Model):
title = ndb.StringProperty(required = True)
vote_count = ndb.IntegerProperty(default = 0)
The HTML would look like this:
<h2>{{story.title}}</h2>
<div>
{{story.vote_count}} | <a href="#">Vote Up Story</a>
</div>
How does AJAX fit inside here?
Answer
Ok Sir here we go... A simple app with one story and infinite votes... ;-)
app.yaml
application: anotherappname
version: 1
runtime: python27
api_version: 1
threadsafe: true
default_expiration: "0d 0h 5m"
libraries:
- name: jinja2
version: latest
- name: webapp2
version: latest
handlers:
- url: .*
script: main.app
main.py
import logging
from controllers import server
from config import config
import webapp2
app = webapp2.WSGIApplication([
# Essential handlers
('/', server.RootPage),
('/vote/', server.VoteHandler)
],debug=True, config=config.config)
# Extra Hanlder like 404 500 etc
def handle_404(request, response, exception):
logging.exception(exception)
response.write('Oops! Naughty Mr. Jiggles (This is a 404)')
response.set_status(404)
app.error_handlers[404] = handle_404
models/story.py
from google.appengine.ext import ndb
class Story(ndb.Model):
title = ndb.StringProperty(required=True)
vote_count = ndb.IntegerProperty(default = 0)
controllers/server.py
import os
import re
import logging
import config
import json
import webapp2
import jinja2
from google.appengine.ext import ndb
from models.story import Story
class RootPage(webapp2.RequestHandler):
def get(self):
story = Story.get_or_insert('Some id or so', title='A voting story again...')
jinja_environment = self.jinja_environment
template = jinja_environment.get_template("/index.html")
self.response.out.write(template.render({'story': story}))
@property
def jinja_environment(self):
jinja_environment = jinja2.Environment(
loader=jinja2.FileSystemLoader(
os.path.join(os.path.dirname(__file__),
'../views'
))
)
return jinja_environment
class VoteHandler(webapp2.RequestHandler):
def post(self):
logging.info(self.request.body)
data = json.loads(self.request.body)
story = ndb.Key(Story, data['storyKey']).get()
story.vote_count += 1
story.put()
self.response.out.write(json.dumps(({'story': story.to_dict()})))
and finally
views/index.html
<!DOCTYPE html>
<html>
<head>
<base href="/">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
</head>
<body>
<h2>{{story.title}}</h2>
<div>
<span class="voteCount">{{story.vote_count}}</span> | <a href="javascript:VoteUp('{{story.key.id()}}');" >Vote Up Story</a>
</div>
<script>
function VoteUp(storyKey){
$.ajax({
type: "POST",
url: "/vote/",
dataType: 'json',
data: JSON.stringify({ "storyKey": storyKey})
})
.done(function( data ) { // check why I use done
alert( "Vote Cast!!! Count is : " + data['story']['vote_count'] );
$('.voteCount').text(data['story']['vote_count']);
});
};
</script>
</body>
</html>
Assemble, read it's simple enough and run. If you need a working git example just comment.
githublink (as from comments)