SnapToGrid并在Django中将其值分组

Question

我对Django queryset分组有问题。我需要获取由point捕捉网格ST_SnapToGrid摸索的点的queryset，查询应如下所示：

SELECT
    ST_AsGeoJSON(
        ST_SnapToGrid("events_place"."point", 1),
        8
    ) AS "point_geo",
    MAX("events_place"."adress") AS "adress"
FROM
    "events_place"
GROUP BY
    point_geo

并且代码无效：

models.py

class Place(models.Model):
    kode= models.BigIntegerField(blank=True, null=True)
    adress = models.CharField(max_length=250, blank=True, null=True)
    lat = models.FloatField(blank=True, null=True)
    lng = models.FloatField(blank=True, null=True)
    point = models.PointField(blank=True, null=True)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return str(self.id) + " "+str(self.adress ) + " ("+str(self.lat) + ", " + str(self.lat) + ")"

    class Meta:
        ordering = ('created_at',)
    def save(self, *args, **kwargs):
        super(Place, self).save(*args, **kwargs) # Call the "real" save() method.

views.py

class PlaceSTGViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = Place.objects.all()
    serializer_class = PlaceSTGSerializer


    def get_queryset(self):
        queryset = Place.objects\
            .annotate(point_geo=AsGeoJSON(SnapToGrid('point', 1)), adress=Max('adress'))\
            .values('lng', 'point_geo')

        return queryset 

结果查询无效：

SELECT
    "events_place"."lng",
    ST_AsGeoJSON(
        ST_SnapToGrid("events_place"."point", 1),
        8
    ) AS "point_geo"
FROM
    "events_place"
GROUP BY
    "events_place"."id",
    ST_AsGeoJSON(
        ST_SnapToGrid("events_place"."point", 1),
        8
    )
ORDER BY
    "runis_events_place"."created_at" ASC

问题是它按语句包含了"events_place"."id"。您能告诉我如何摆脱此id吗？

Answer 1

在此问题中找到答案：Django annotate and values(): extra field in 'group by' causes unexpected results，该问题与order_by有关