Django Nonrel and Google App Engine

The guys behind appengine patch have a new project using the Django nonrel project to run on App Engine.

Clone the appropriate projects from bitbucket :

$ hg clone https://[Bitbucket User Name]@bitbucket.org/wkornewald/django-nonrel/
$ hg clone https://[Bitbucket User Name]@bitbucket.org/wkornewald/djangoappengine/
$ hg clone https://[Bitbucket User Name]@bitbucket.org/wkornewald/django-testapp/

The instructions say next, "Now you should be able to create a new app in the testapp folder and use native Django models on App Engine. Try it!"

dignan@dignan-laptop:~/workspace/django-nonrel/django-testapp$ python manage.py runserver
Traceback (most recent call last):
File "manage.py", line 4, in <module>
from djangoappengine.boot import setup_env
ImportError: No module named djangoappengine.boot

Hmmm.

The documentation calls for two symlinks :

django-testapp/common-apps/djangoappengine -> ../../djangoappengine

django-testapp/common-apps/djangoappengine -> ../../django-nonrel/django

I created them and tried again.

The Google App Engine SDK could not be found!
Make sure it's accessible via your PATH environment.

So I added the it to my path and tried again. Same result.

I found the following on the appengine-patch website:

"you can also put the SDK into any folder that is in the system's PATH environment variable as long as it's called "google_appengine" (this works with any OS)"

My sdk was in "google_appengine_1.3.0". I created a symlink, "google_appengine" and tried again.

/home/dignan/tools/appengine/google_appengine_1.3.0/google/appengine/api/datastore_file_stub.py:40: DeprecationWarning: the md5 module is deprecated; use hashlib instead                                                             
import md5                                                                                                    
/home/dignan/tools/appengine/google_appengine_1.3.0/google/appengine/api/memcache/__init__.py:31: DeprecationWarning: the sha module is deprecated; use the hashlib module instead                                                    
import sha
WARNING  2010-03-10 22:41:09,468 datastore_file_stub.py:483] Could not read datastore data from /tmp/django_nonreltest.datastore
Traceback (most recent call last):
File "workspace/django-norel/django-testapp/manage.py", line 16, in <module>
execute_manager(settings)
File "/home/dignan/workspace/django-norel/django-testapp/common-apps/django/core/management/__init__.py", line 438, in execute_manager
utility.execute()
File "/home/dignan/workspace/django-norel/django-testapp/common-apps/django/core/management/__init__.py", line 379, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "workspace/django-norel/django-testapp/common-apps/djangoappengine/management/commands/runserver.py", line 88, in run_from_argv
start_dev_appserver(argv)
File "workspace/django-norel/django-testapp/common-apps/djangoappengine/management/commands/runserver.py", line 74, in start_dev_appserver
dev_appserver_main.main([progname] + args + [os.getcwdu()])
File "/home/dignan/tools/appengine/google_appengine_1.3.0/google/appengine/tools/dev_appserver_main.py", line 360, in main
config, matcher = dev_appserver.LoadAppConfig(root_path, {})
File "/home/dignan/tools/appengine/google_appengine_1.3.0/google/appengine/tools/dev_appserver.py", line 3441, in LoadAppConfig
raise AppConfigNotFoundError
google.appengine.tools.dev_appserver.AppConfigNotFoundError

At least it started! I cd'd into the app's directory and ran:

python manage.py runserver

It started up. I got the default "It worked!" page.

Using the Google App Engine Helper for Django

Working through the steps to install the Google Appengine Helper for Django, I zipped up Django 1.1 and placed it in the root directory. I ran, "python manage.py runserver" and got the following error :

dignan@dignan-laptop:~/workspace/python/[PROJECT_NAME]$ python manage.py runserver
ERROR:root:Django 1.0 or greater is required!

The solution was simple. I zipped up the "django" folder inside the complete distro and put it in the root.

app-engine-patch Database problems

I've been using app-engine-patch to get some Django stuff running on Google AppEngine.

Several times my admin password has been reset or invalidated. On a couple of occasions I recreated the admin user from the link on the default page. After styling the site this wasn't possible.

I added the "create_admin_user" entry from the generated myapp/urls.py to the root level urls.py and manually entered the url. That worked.

Google AppEngine

New Google AppEngine!

Sweet, couldn't wait to use it. I started the tutorial during lunch. I downloaded and installed Python and the AppEngine. Then I created a work directory, "C:\google_workspace" and a helloworld folder, "C:\google_workspace\helloworld" just like the tutorial said to do, created the files "helloworld.py" and "app.yaml" just like in the tutorial, and fired up the dev_appserver with, "C:\google_workspace\helloworld>dev_appserver.py helloworld\". Instead of "Hello, world!" I got :

C:\google_workspace\helloworld>dev_appserver.py helloworld/
Traceback (most recent call last):
File "C:\Program Files\Google\google_appengine\dev_appserver.py", line 50, in
<module>
execfile(script_path, globals())
File "C:\Program Files\Google\google_appengine\google/appengine/tools/dev_apps
erver_main.py", line 338, in <module>
sys.exit(main(sys.argv))
File "C:\Program Files\Google\google_appengine\google/appengine/tools/dev_apps
erver_main.py", line 287, in main
config, matcher = dev_appserver.LoadAppConfig(root_path, {})
File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_apps
erver.py", line 2415, in LoadAppConfig
raise AppConfigNotFoundError
google.appengine.tools.dev_appserver.AppConfigNotFoundError

Hmm. I ran through a mental checklist before diving into the code (I knew I was being lazy. I was also really looking forward to diving into the code, but I wanted to at least get the thing running first.)

• Perhaps I should've installed somewhere other than "C:\Program Files" I don't usually put anything in there.
• Apparently I had Tomcat running which would be blocking 80 (I usually set Tomcat to 80 and JBoss to 8080).

Neither of those made a difference. "I, d, ten, t" error - I was running the wrong file.

Running, "C:\google_workspace\helloworld>dev_appserver.py ./" started the server.

The first line was a prompt, "Allow dev_appserver to check for updates on startup? (Y/n):"
Naturally I said "Y", and I liked name of the config file which was conveniently printed out on the next line, "dev_appserver will check for updates on startup. To change this setting, edit C
:\Documents and Settings\jdavis/.appcfg_nag"

I saw "Hello, world!"

I can't wait to start using this. Now I can finally build a completely scalable side project to make myself rich without spending any money out of pocket! Actually, I can finally stop putting off learning Python.

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