Use only some parts of Django?

Question

I like Django, but for a particular application I would like to use only parts of it, but I'm not familiar enough with how Django works on the inside, so maybe someone can point me into the right direction as to what I have to check out.

Specifically, I want to use:

• The models and database abstraction
• The caching API, although I want to avoid database lookups by caching, not HTML generation, and since the caching framework in Django is intended for the latter, I'm not sure yet whether that's really appropriate.

I would not use:

• Templating
• urlconfigs

Or, more exactly, I'm neither using HTTP nor HTML. So basically, I have a different input / output chain than usual.

Can this work?

My personal killer feature in Django is the Object / database mapping that I can do with the models, so if there's another technology (doesn't have to be Python, I'm in the design phase and I'm pretty agnostic about languages and platforms) that gives me the same abilities, that would be great, too.

Answer 1

There are of course other projects out there that specifically implement single parts of django. TurboGears for example is a collection of several projects that can work by themselves and together form a complete web development framework.

For the db abstraction SQLAlchemy comes to mind.

Regarding the caching part: I'm not aware of any standalone project that implements a generic caching facility.

On the other hand, it should be fairly easy to implement your own caching, for example by using pickles. Have a look at this recipe for a decorator for ideas and google for "memoize".

Also keep in mind that your database has its own caching mechanism, so maybe you don't even need to concern yourself with the details.

Answer 2

I tend to prefer a mix-and-match approach to using Python for web programming. :-)

I don't have a lot of experience with Django, but I'd recommend giving sqlalchemy a look for the database stuff. It works well with others and gives you several potential layers of abstraction (so you can go with something basic or tweak the hell out of it if you want). Plus, you'll already be somewhat familiar with it if you've ever used hibernate/nhibernate.

My favorite part is that it has a lot of options for databases to connect to (most notably SQL Server, which django doesn't have built in last time I checked).

With that said, I'm told that with Django, it's pretty easy to decouple functionality (but never done so myself).

Answer 3

I myself use Django for its object/db mapping without using its urlconfigs. Simply create a file called djangosettings.py and insert the necessary configuration, for example:

DATABASE_ENGINE   = 'oracle'
DATABASE_HOST     = 'localhost'
DATABASE_NAME     = 'ORCL'
DATABASE_USER     = 'scott' 
DATABASE_PASSWORD = 'tiger'

Then in your regular Python code, do

import os
os.environ["DJANGO_SETTINGS_MODULE"] = "djangosettings.py"

before you import any Django modules. This will let you use Django's object/db mappings without actually having a Django project, so you can use it for standalone scripts or other web applications or whatever you want.

As for caching, if you don't want to use Django then you should probably decide what you are using and go from there. I recommend using CherryPy, which doesn't use Django-style regular expression URL mapping, but instead automatically maps URLs to functions based on the function names. There's an example right at the top of the CherryPy home page: http://cherrypy.org/

CherryPy has its own caching system, so you can accomplish exactly the same thing as what Django does but without needing to use Django's urlconfig system.

Answer 4

Django, being a web framework, is extremely efficient at creating websites. However, it's also equally well-suited to tackling problems off the web. This is the loose coupling that the project prides itself on. Nothing stops you from installing a complete version of Django, and just using what you need. As a rule, very few components of Django make broad assumptions about their usage.

Specifically:

• Django models don't know anything about HTML or HTTP.
• Templates don't know anything about HTML or HTTP.
• The cache system can be used to store anything that can be pickled.

One of the main things you'll face when trying to use Django without a web server is setting up the environment properly. The ORM and cache system still need to be configured in settings.py. There are docs on using django without a settings module that you may find useful.