CODEWITHSUNDEEP
djangogoogle-app-engine
Pratyush
Pratyush

Reputation: 5478

How to migrate Django project to Google App Engine

I am looking for a guide to migrate Django project to Google App Engine and use Google's datastore. The most of the guides I found were linked to Django-Appengine using Django-nonrel (but I want to use GAE's native support).

Going through GAE getting started guide, it says:

Google App Engine supports any framework written in pure Python that speaks CGI (and any WSGI-compliant framework using a CGI adaptor), including Django, CherryPy, Pylons, web.py, and web2py. You can bundle a framework of your choosing with your application code by copying its code into your application directory.

I understand that I won't be able to use some features of Django in that case (majorly the admin feature) and would also need to restructure the models.

From other reading, I also found that latest SDK of GAE now includes Django 1.3 on Python 2.5.

I tried to put all files from my Django application to a GAE project, but couldn't get it all to work together.

Please provide some basic guide using which I may migrate my Django project to Google App Engine's code.

Thanks.

Upvotes: 2

Views: 3143

Answers (3)

chachan
chachan

Reputation: 2452

If you already have a Django application you might want to check this out. You won't work with App Engine's datastore but Google Cloud SQL might fit your needs.

Upvotes: 1

dragonx
dragonx

Reputation: 15143

I've used django-nonrel, which behaves pretty much like django, except that operations with JOINs will return errors. I've basically worked around this by avoiding ManyToMany fields, and essentially building that functionality manually with an intermediate table.

So far I've ran into two problems with Django-nonrel: 1. No access to ancestor queries, which can be run in a transaction. There's a pending pull request for this feature though. 2. You can't specify fields that are not indexed. This could significantly increase your write costs. I have an idea to fix this, but I haven't done so yet.
(Edit: You CAN specify fields that are not indexed, and I've verified this works well). 2 (new). Google is pushing a new database backend called ndb that does automatic caching and batching, which will not be available with django-nonrel.

If you decide not to use django-nonrel, the main differences are that Django models do not run under App Engine. You'll have to rewrite your models to inherit from App Engine's db.Model. Your forms that use Django's ModelForm will need to inherit from google.appengine.ext.db.djangoforms instead. Once you're on App Engine, you'd have to port back Django if you ever take your app somewher else.

Upvotes: 2

Guido van Rossum
Guido van Rossum

Reputation: 16890

For an existing Django app, using django-nonrel is the simplest approach; it is very popular so you should be able to find help with specific errors you get quickly.

Another approach is written up in this article: http://code.google.com/appengine/articles/pure_django.html -- it goes the other way, taking an App Engine app that uses Django for dispatch, templates, and forms, but not for models, and describes how to make it run in a native Django environment. Maybe you can glean some useful hints for your situation from it.

Upvotes: 2

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