Dear Django community,
I have a data model that looks like the following:
class Submission(models.Model):
...
class Assessment(models.Model):
submission = models.ForeignKey(
Submission, on_delete=models.CASCADE, related_name='assessments')
time_stamp = models.DateTimeField()
And I would like to do something simple such as computing a list of pairs
of submissions and their most recent assessments:
qs = Submission.objects.prefetch_related('assessments')
xs = [(s, s.assessments.latest('time_stamp')) for s in qs.all()]
This seems to be inefficient because the assessments table seems to be
queried for each submission.
I've read about prefetch_related and tried to use it as above but it
doesn't seem to have any effect.
I suppose this is because I try to use 'latest'?
Is prefetch_related applicable in this case at all or do I need to resort
to a different technique like a raw SQL query?
Thanks in advance!
Simon
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