how to render django template from code instead of file on Google App Engine

In order to render a template 'in memory', there are a few things you'll need to do:

App Engine Setup

First of all, you'll need to ensure that everything is set up correctly for Django. There's a lot of information on the Third-party libraries page, but I'll include it here for your benefit.

In main.py, or (whatever your script handler is), you'll need to add the following lines:

import os
os.environ['DJANGO_SETTINGS_MODULE'] = 'settings'

from google.appengine.dist import use_library
use_library('django', '1.2') # Change to a different version as you like

Don't forget to include django in your app.yaml:

libraries:
    - name: django
      version: "1.2"

Code Setup

Second of all, you'll need to create a Template object, as denoted in the Google App Engine template documentation. For example:

from google.appengine.ext.webapp import template

# Your code...
template_string = "Hello World"
my_template = template.Template(template_string)

# `context` is optional, but will be useful!
# `context` is what will contain any variables, etc. you use in the template
rendered_output = template.render(context)

# Now, do what you like with `rendered_output`!

You can instantiate a template from text in Django with just template.Template(my_text).