How to use select_related with GenericForeignKey in django?

Question

I have a situation wherein a large number of objects of a particular class are being iterated over, and they take a huge amount of time for processing because I can't pre-select data using select_related.

The class in question goes something like below

from django.contrib.contenttypes.models import ContentType
from django.db import models

class Offer(models.Model):
    ...
    object_id = models.PositiveIntegerField(db_index = True)
    content_type = models.ForeignKey(ContentType, db_index = True)
    content_object = generic.GenericForeignKey('content_type', 'object_id')
    ...

I have tried using select_related like below, but it obviously doesn't work

offerList = Offer.objects.select_related('content_type', "content_object"
    ).filter(content_type=ContentType.objects.get_for_model(SomeObject),
    object_id=someobject.id)

So, how can I use select_related with GenericForeignKey in django?

Answer 1

It is not select_related what you are looking for. It is prefetch_related, which

supports prefetching of GenericRelation and GenericForeignKey.

Therefore, your base command would be:

Offer.objects.all().prefetch_related('content_object')