How to create a simple app on appengine

• First, go to AppEngine and create a new application. You can do this from your gmail account (so that the app will always be yours), or if you don't have a gmail account, from your @ucsc.edu account (in which case you won't be able to access the app, once you are no longer a student, unless you manage to transfer its ownership to a personal account). Remember the application id appid you created..
• Download this web2py package (feel free to update it using git if you want the latest web2py version, at your risk, by doing a git fetch ; git merge origin/master from the main directory of the package.).
  • The documentation for web2py (especially, the book), and versions you can also download, are available at the web2py main site. The package above is pre-set to be used on appengine.
• Edit app.yaml to have the application match the application you created.
• Download the Google Appengine SDK for Python.
• Upload your application. If you use the command line tools like me, if you install it in a google_appengine subdirectory (the default), do:

   google_appengine/appcfg.py --email=youremail@gmail.com --no_cookies update web2py-student-starter/

• Of course, feel free to rename the directory from web2py-student-starter to something else!
  • You can also run the code locally as follows, and then point your browser to http://127.0.0.1:8888/classexample/default/get.json/behappy/luca/12 for testing (or to whatever other URL you need to use, see below for more information).

   google_appengine/dev_appserver.py --port 8888 --admin_port 8880 web2py-student-starter/

classexample

The package contains a very simple app, classexample, which can be used as a key value store.

You can use it as follows:

First, change MYSECRET in applications/classexample/controllers/default.py to be yoursecret.

To write a piece of data, you can do:

https://appid.appspot.com/classexample/default/put.json/yoursecret/appname/key?c=hello

Where:

• appname is a parameter of your choice, e.g., the application name you are building.
• key is the key
• hello is the value

You can also use a POST request, assigning to the variable c the value you want to store for appname and key.

To read, you can use:

https://appid.appspot.com/classexample/default/get.json/yoursecret/appname/key

and you will get a reply like:

{"result": "hello"}

that you can decode using json.

If you include MYSECRET in your Android app, and always use ssl (https) as above to access your appengine app, you will have at least a modicum of security. But always use https, otherwise the information will be sent around in the clear.

Creating your own app

To create your app, instead of classexample, simply copy applications/classexample to applications/yourapp.

Then:

• Edit yourapp/models/tables.py if you wish to define different tables.
• Every path of the form appid.appspot.com/yourapp/f/g.json maps to a function g() (without arguments) defined in yourapp/controllers/f.py . See the example in the class app.
  • Look at the web2py documentation for more information.