合并 django 查询集上的行

Question

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:

Location	Person	Error
L1	P1	false
L1	P1	true
L2	P2	false
L2	P2	false

Location	Person	Error
L1	P1	true
L2	P2	false

Answer 1

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}

Answer 2

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)