使用values()获取Django GeometryField的坐标 [英] Get Django GeometryField's coordinates with values()

问题描述

我有一个带GeometryField的模型.像这样-

I have a model with a GeometryField. Like this -

from django.contrib.gis.db import models as geo_models

class School(BaseModel):
    # Some fields
    centroid = geo_models.GeometryField(blank=True, null=True)

我正在使用values()方法过滤值，因为我必须从QuerySet中生成JSON-

And I'm filtering the values with the values() method because I have to generate a JSON out of the QuerySet -

class SearchView(View, JSONResponseMixin):
    def get(self, *args, **kwargs):
        params = self.request.GET
        results = {}
        schools = School.objects.values('id', 'code', 'name')
        # More stuff here

但是我也需要在JSON中返回纬度和经度.将centroid放在values()中只会返回加密的十六进制值.我怎样才能把坐标吐出来?

But I need to return the latitude and longitude in the JSON too. Putting centroid in values() just returns the encrypted hex value. How do I get it to spit the coordinates out?

推荐答案

经过大量研究，不得不像这样使用PostGIS的ST_AsGeoJSON()功能-

After much research, had to use the ST_AsGeoJSON() function of PostGIS like this -

schools = School.objects.extra(
    select={
        'centroid': 'ST_AsGeoJSON("schools_school"."centroid")'
    }
).values('code', 'name', 'centroid')

结果，我得到了与JSON兼容的数据-

As a result, I get the JSON compatible data -

{
    "results": [
        {
            "code": "12345678",
            "centroid": "{\"type\":\"Point\",\"coordinates\":[75.32559653,16.906422997]}",
            "name": "SCHOOL NAME"
        },
        // more
    ]
}

我仍然需要在客户端对它进行反序列化，但是我认为这是可行且可以接受的.至少我得到JSON.

I'd still have to deserialize it on client side, but I guess that's doable and acceptable. At least I get JSON.

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