I have a querset with attributes location, person and error

I need to either create a new queryset or edit an existing one such that rows are "combined" based on a certain criteria This criteria is if the location and person are the same Once combined, I want to make the error value be true if any of the rows that are being combined had a true value In this case the table should be changed as follows:

CodePudding user response：

Okay, so to help you out you can do this:

MyModel.objects.filter(your query).values('location', 'person').distinct()

by using .distinct() no duplicates will be present and you shall achieve what you want. (which also serves the purpose if location and person are the same for 2 rows)

CodePudding user response：

You shouldn't use aggregate() for this purpose, but annotate() (docs).

Input:

class T(models.Model):
    person = models.CharField(max_length=10)
    location = models.CharField(max_length=10)
    error = models.BooleanField()

T.objects.bulk_create([
    T(person='P1', location='L1', error=False),
    T(person='P1', location='L1', error=True),
    T(person='P2', location='L2', error=False),
    T(person='P2', location='L2', error=False)
])
for t in T.objects.all().values('person', 'location').distinct().annotate(error=Sum('error')):
    print(t)

Output:

{'person': 'P1', 'location': 'L1', 'error': True}
{'person': 'P2', 'location': 'L2', 'error': False}