As a sort of challenge to myself, I once again attempted to recreate ticket #17 as a standalone component. After a few hours, and some previous code I had written as a good guide, it seems to be working. So I’d like to announce django-idmapper.

The goal of the project is a simple plug-and-play system for integrating the identity mapper into the ORM components. It allows you it simply define as a model with a different base class (via the SharedMemoryModel class), and all queries against this model (yes even from non-singleton models) are directed through the unique instance cache.

In many cases, this can provide a nice decrease of memory usage, and you may even see a nice speed bonus (as we did with Curse).

Here is a nice and dirty quick example of a situation which would gain from this benefit:

from idmapper import models
 
class Category(models.SharedMemoryModel):
    # We have 5 categories
    name = models.CharField(max_length=32)
 
class Article(models.SharedMemoryModel):
    # And 100 articles
    name = models.CharField(max_length=32)
    category = models.ForeignKey(Category)

Now in a (sort of) typical query, maybe we want to show every article (or 100, which isn’t too unreasonable). We also want to show the category they are in:

article_list = Article.objects.all().select_related('category')

What we have achieved here, is only having a maximum of N (where N is the number of categories) unique instances of category in memory here. Since we only have five, this means that we only created five category instances. This gives us a savings of the time it takes to create the additional 95 category objects, as well as the memory they would have consumed.

Please let me know if you run in to any problems, but so far, the tests are passing

Note: I’ve renamed the project due to the incorrect terminology. My apologies