Select a COUNT using Django model?

Question

Does anyone know if there's a way to just select the number of rows matching a query in Django? I have a search I've written that splits results into sets of 40, but I'd like to display the total number of results as well. I could to something like len(Model.objects.filter(name__icontains=search)), but it seems like that would be grossly inefficient (since I'm assuming that would generate a "SELECT * FROM model" and then all of the resulting objects). Any suggestions?

Answer 1

Use count():

>>> Model.objects.count()
42
>>> Model.related_set.count()
102
>>> Model.related_set.filter(blah=42)
3

Answer 2

There are two main ways to handle this:

1. Use Django's count() QuerySet method — simply append count() to the end of the appropriate QuerySet
2. Generate an aggregate over the QuerySet — Aggregation is when you "retrieve values that are derived by summarizing or aggregating a collection of objects." Ref: Django Aggregation Documentation

The links above are to the applicable sections of Django's documentation.