django-standalone 0.4
use the Django ORM with standalone scripts
License: BSD
Keywords: django standalone script orm

-*- markdown -*-

Simple Standalone Scripts Using the Django ORM
=====================================================

This little library is all about easing the pain of using
the Django ORM for simple tools that just happen to be in need
of some easy to use ORM for object persistence.

The best way of course is to set up a full Django project and
just use a settings.py file and using the DJANGO_SETINGS_MODULE
environment variable. But when you just want to do little tools
that just need some sqlite3 database to store some of their
data and don't want to go for a full Django project, that is
where this little library comes into play.

It consists of just two modules so far:

standalone.conf handles all the configuration needs, setting up

standalone.models carries a base class for your models that
automatically tells Python that all models created actually
reside in the standalone Django app, even though they are
in a different file, outside the app's namespace.

As a warning: this might be seen as voodoo, bad magic or just
a plain stupid idea by some people. And the official way
to do it might be a much better idea for you. I myself just
happen to like to have the ability to easily create standalone
executable scripts that don't rely on some predefined project
structure.

how to get it
---------------

The easiest way to get django-standalone is to use easy_install
or pip:

sudo easy_install django-standalone

or

sudo pip install django-standalone

Or you can clone this repository and run the included setup.py

To run the included test cases, just run the following:

pythons setup.py test

using in your scripts:
------------------------

First create a dynamic configuration for your database
connection:

 from standalone.conf import settings
 settings = settings(
     DATABASE_ENGINE='sqlite3',
     DATABASE_NAME=options.database,
 )

this is all you need to do to have django modules working
in your script. You would have to add additional settings if
you want to use more than just the ORM, for example you will
have to add TEMPLATE_DIR if you want to use the template modules.

You can add any django setting you want - standalone.conf will
allways extend your settings, never overwrite them.

Now you just define a bunch of Models, using the provided base
class in your script. The needed module standalone.models
reexports everything from django.models, so you only need one.

 from standalone import models

 class MyModel(models.StandaloneModel):

     col1 = models.CharField(max_length=1000)
     col2 = models.IntegerField()
     col3 = models.BooleanField()

     def __unicode__(self):
         return self.col1

This will create the model and will make it available directly
in your script. Additionally it will make them available in the
module standalone.models for access by modules you might import
in your script or for access in the django shell.

This patching into standalone.models only happens for models
defined in scripts, though - if your models reside in proper
python modules, nothing of that kind will happen, as they
are easily accessible to modules or the shell in their original
module. If for any reason you need to force install into
standalone.models, too (for example the testing uses this
to make sure the model is accessible in a standard place even
though defined in a module), you can add a class variable
force_install_standalone_models with a true value.

If you want to access a Django shell with access to your models,
you can just use the standard way to access management commands
from scripts:

 from django.core.management import call_command
 call_command("shell")

The same way can be used to actually create the tables, too. Put
the following lines directly after your model declarations and
your script will automatically set up the database tables if they
don't yet exist.

 from django.core.management import call_command
 call_command("syncdb")

Using with a library of models
--------------------------------

You can create library modules with model definitions based
on StandaloneModel, too. These won't be patched into standalone.models,
though, so you have to reference them by their own modules. They
can reference models in your script by using symbolic names.

 from standalone import models

 class MyOtherModel(models.StandaloneModel):

     col1 = models.CharField(max_length=100)
     col2 = models.ForeignKey("standalone.MyModel")

To write a class that again references this library model, just do
something like the following:

 from mylibrary.mymodels import MyOtherModel

 class AndYetAnotherModel(models.StandaloneModel):

     col1 = models.ForeignKey(MyOtherModel)

There are situations where you need to force a model to be installed
into standalone.models to make sure you can access it from other
places. One such situation is setUp methods in test cases. For that
purpose, you can define an option as follows:

 class AllwaysInstalledModel(models.StandaloneModel):
     force_install_standalone_models = True

     col1 = models.CharField(max_length=100)

This model will not only reside in it's own scope but will additionally
be hooked up in standalone.models as a global value.

CAVEAT: even if a model is not installed into standalone.models,
they will allways be regarded as models of the standalone application.
Which means, their table names will all start with 'standalone_'
in the database! This has to do with the fact that django only likes
model definitions that are linked to some installed django application
and django-standalone behaves as an umbrella application for all
models defined in the context of a script.

contacting the author
-----------------------

Can be done at gb at rfc1437.de in case of problems. Allthough, as the
license says, essentially it's a "if you break it, you have to keep
the pieces" thing. Of course, I allways like to hear war stories. Just
don't blame me if this little lib kills your production server, hunts
down your boss and eradicates all your companies expense records.