When there is a DateTimeField django does not group by

[Fabio García Sánchez]

I have 2 models, both have almost the same fields. Just one of them has a DateTimeField.
The problem comes when I try to group by (not on the DateTimeField) and summarize using Sum in annotate. The model that does not have the DateTimeField works properly, the other groups by day, the Sum is per day.

qs1 = Bills.objects.values('tipo_documento').annotate(total=Sum('venta_neto'))
print(qs1 )
<QuerySet [{'tipo_documento': 'FV', 'total': Decimal('8419159.0000')}, {'tipo_documento': 'FY', 'total': Decimal('12500000.0000')}, {'tipo_documento': 'FY', 'total': Decimal('210000.0000')}...

debug_toolbar shows, effectively is grouping by "document_date", but I have just "tipo_documento" in values:

SELECT `biable_facturasbiable`.`tipo_documento`, SUM(`biable_facturasbiable`.`venta_neto`) AS `cosa` FROM `biable_facturasbiable` GROUP BY `biable_facturasbiable`.`tipo_documento`, `biable_facturasbiable`.`document_date` ORDER BY `biable_facturasbiable`.`document_date` DESC LIMIT 21

this repeat the type ('tipo_documento'), each Total is per day.

On the other hand, the model without DateTimeField work properly:

qs2 = Bills2.objects.values('tipo_documento').annotate(total=Sum('venta_neto'))
print(qs2 )
<QuerySet [{'tipo_documento': 'FV', 'total': Decimal('22367372215.1000')}, {'tipo_documento': 'NV', 'total': Decimal('-38955434.0000')}, {'tipo_documento': 'NI', 'total': Decimal('0.0000')}, {'tipo_documento': 'FY', 'total': Decimal('10155529934.9700')}]>

qs2 works properly. I have tried to do the same example with another models and I have got the same issue.

debug_toolbar shows:

SELECT `biable_movimientoventabiable`.`tipo_documento`, SUM(`biable_movimientoventabiable`.`venta_neto`) AS `cosa` FROM `biable_movimientoventabiable` GROUP BY `biable_movimientoventabiable`.`tipo_documento` ORDER BY NULL LIMIT 21

Thanks