Question

Let’s say I have the following Django model:

class Info(models.Model):
    instrument = models.ForeignKey('Instrument')
    date = models.DateTimeField()

How can I extract the entry with the newest date for each Instrument ?

Answer 1

Try this:

Instrument.objects.all().annotate(max_date=models.Max("info__date"))

It will return a list of all instruments and each intrument will have additional attribute max_date which contains the latest date for this instrument.