Getting Started with Python in Google App Engine

Question

I'm just getting started in python with google app engine using the webapp2 framework and jinja2 templating. I can't seem to get my first and very simple script up and running. All I want is for the script to serve the index.html file(located in the same directory).

Here is the app.yaml file:

libraries
- name: webapp2
  version: latest
- name: jinja2
  version: latest

application: practice
version: 1
runtime: python27
api_version: 1
threadsafe: true

handlers:
- url: /.*
  script: practice.application

Here is practice.py:

import os
import webapp2
from jinja2 import Enviroment, FileSystemLoader

loader = jinja2.FileSystemLoader(os.path.dirname(__FILE__)
env = jinja2.Enviroment(loader)

class MainPage(webapp2.RequestHandler):
    def get(self):
        template = env.get_template('index.html')
        self.response.write(template.render())

application = webapp2.WSGIApplication([
 ('/', MainPage),
 ], debug=True)

Update: I am running this locally from the Google app engine launcher. When I attempt to open the file I receive a server error with the description

The website encountered an error while retrieving http://localhost:9080/. It may be
down for maintenance or configured incorrectly."

Answer 1

Here's why your code won't run:

• Your app.yaml is malformed
• Enviroment is spelt wrong
• Your missing a closing bracket on line 5
• You haven't imported the jinja2 library
• The variable __ FILE __ is undeclared

Here's what I think your code should look like:

app.yaml

application: practice
version: 1
runtime: python27
api_version: 1
threadsafe: true

libraries:
- name: webapp2
  version: latest
- name: jinja2
  version: latest

handlers:
- url: /.*
  script: practice.application

practice.py

import jinja2
import os
import webapp2

loader = jinja2.FileSystemLoader(os.path.dirname(__file__))
env = jinja2.Environment(loader=loader)

class MainPage(webapp2.RequestHandler):
    def get(self):
        template = env.get_template('index.html')
        self.response.write(template.render())

application = webapp2.WSGIApplication([
 ('/', MainPage),
 ], debug=True)

I suggest you do the following to make your life a LOT easier:

• download eclipse (I assume you haven't given the syntax errors) -> http://eclipse.org/
• complete the tutorial -> https://developers.google.com/appengine/docs/python/gettingstartedpython27/introduction
• read the docs -> https://developers.google.com/appengine/docs/python/

Hope this helps get you on your way.

Happy coding :)

Answer 2

在webapp2中，您应该使用 app而不是application ，所以最后一行应如下所示：

app = webapp2.WSGIApplication([('/', MainPage),], debug=True)