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POWhat's wrong with my channel api code?
 

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  1. POWhat's wrong with my channel api code?
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    <p>I've been working on getting a website together with GAE and the channel api to display and process real time data from a robot I'm working on. I'm pretty new to web development, and python in general, but it seems to me like this code should work I'll make it more fancy once I get it working (logging data into a database, actual data processing etc.), but for now I just want it to display the most recent occurance of the variable "val" from a post request sent from the internet connected board on the robot. Hopefully this will be helpful to anyone looking to do real time data display with the channel api.</p> <p>Right now I'm displaying a template with an input box set to send a post request to the page. Instead of updating the front page with the current value on submission however, I get a blank screen. I'm not sure if my problem actually has to do with the channel api code, or the java function for updating the displayed value.</p> <p>Python code:</p> <pre><code>import os import webapp2 import jinja2 import json import logging from google.appengine.ext import db from google.appengine.api import channel from google.appengine.api import users template_dir = os.path.join(os.path.dirname(__file__), 'templates') jinja_env = jinja2.Environment(loader = jinja2.FileSystemLoader(template_dir), autoescape=True) channels = [] class MainPage(webapp2.RequestHandler): def get(self): user = users.get_current_user() if not user: self.redirect(users.create_login_url(self.request.uri)) return nickname = user.nickname() clientid = user.user_id() channel_token = channel.create_channel(clientid) channels.append(channel_token) template_values = {'channel_id': channel_token, 'nickname': nickname} template = jinja_env.get_template('front.html') self.response.out.write(template.render(template_values)) def post(self): value = self.request.get("value") if value: jsn = json.dumps({"val": value}) for i in range(len(channels)): channel.send_message(channels[i], jsn) app = webapp2.WSGIApplication([ ('/', MainPage) ], debug=True) </code></pre> <p>Relevant part of HTML Template:</p> <pre><code> &lt;form method="post"&gt; &lt;label&gt; &lt;div&gt;Title&lt;/div&gt; &lt;input type="text" name="value" value="{{value}}"&gt; &lt;/label&gt; &lt;br&gt; &lt;input type="submit"&gt; &lt;div class="error"&gt;{{error}}&lt;/div&gt; &lt;/form&gt; &lt;hr&gt; &lt;script&gt; onMessage = function myFunction(message) { document.getElementById("val").innerHTML=message; } var token = '{{ channel_id }}'; var channel = new goog.appengine.Channel(token); var socket = channel.open(); socket.onmessage = onMessage(message.val); &lt;/script&gt; &lt;p id="val"&gt;No value to display&lt;/p&gt; &lt;/body&gt; </code></pre> <p></p> <p>Thanks in advance.</p>
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