Question

I have some simple Django Models like this:

class Event(models.Model):
    # some stuff

class Price(models.Model):
    event = models.ForgeinKey(Event)

i.e. each Event has 1 or more Price‘s.

I am selecting some Events like this: events = Event.objects.filter(…), and then looping over them for event in events:, inside the loop I need to access all the Price objects for each event (i.e. with event.price_set), however that does a new SQL query for each event. I have thousands of events, and this is causing thousands of queries. Is there some way I can prepopulate the price_set for each event all in one go?

I tried adding a select_related to the QuerySet, but it doesn’t work (I can still see all the queries in the Django Debug Toolbar). Surely there’s some way to do a join on the original SQL query which will bring in all the Event‘s and their Prices in one query?

Answer 1

Have a look at: https://github.com/lilspikey/django-batch-select/
It will allow you to get what you want with just 2 queries (1 for the events and 1 for the prices)