Google App Engine with local Django 1.1 gets Intermittent Failures
- by Jon Watte
I'm using the Windows Launcher development environment for Google App Engine.
I have downloaded Django 1.1.2 source, and un-tarrred the "django" subdirectory to live within my application directory (a peer of app.yaml)
At the top of each .py source file, I do this:
import settings
import os
os.environ["DJANGO_SETTINGS_MODULE"] = 'settings'
In my file settings.py (which lives at the root of the app directory, as well), I do this:
DEBUG = True
TEMPLATE_DIRS = ('html')
INSTALLED_APPS = ('filters')
import os
os.environ["DJANGO_SETTINGS_MODULE"] = 'settings'
from google.appengine.dist import use_library
use_library('django', '1.1')
from django.template import loader
Yes, this looks a bit like overkill, doesn't it?
I only use django.template. I don't explicitly use any other part of django.
However, intermittently I get one of two errors:
1) Django complains that DJANGO_SETTINGS_MODULE is not defined.
2) Django complains that common.html (a template I'm extending in other templates) doesn't exist.
95% of the time, these errors are not encountered, and they randomly just start happening. Once in that state, the local server seems "wedged" and re-booting it generally fixes it.
What's causing this to happen, and what can I do about it? How can I even debug it?
Here is the traceback from the error:
Traceback (most recent call last):
File "C:\code\kwbudget\edit_budget.py", line 34, in get
self.response.out.write(t.render(template.Context(values)))
File "C:\code\kwbudget\django\template\__init__.py", line 165, in render
return self.nodelist.render(context)
File "C:\code\kwbudget\django\template\__init__.py", line 784, in render
bits.append(self.render_node(node, context))
File "C:\code\kwbudget\django\template\__init__.py", line 797, in render_node
return node.render(context)
File "C:\code\kwbudget\django\template\loader_tags.py", line 71, in render
compiled_parent = self.get_parent(context)
File "C:\code\kwbudget\django\template\loader_tags.py", line 66, in get_parent
raise TemplateSyntaxError, "Template %r cannot be extended, because it doesn't exist" % parent
TemplateSyntaxError: Template u'common.html' cannot be extended, because it doesn't exist
And edit_budget.py starts with exactly the lines that I included up top.
All templates live in a directory named "html" in my root directory, and "html/common.html" exists. I know the template engine finds them, because I start out with "html/edit_budget.html" which extends common.html.
It looks as if the settings module somehow isn't applied (because that's what adds html to the search path for templates).
