postgis mvt矢量切片 django drf mapboxgl

with mvtgeom as (
select ST_AsMVTGeom(ST_Transform(geom, 3857), ST_TileEnvelope(1,0,0)) as geom, gid 
    from 
    zzz, 
    (select ST_SRID(geom) as srid from zzz where geom is not null limit 1) a
    where
      ST_Intersects(geom, ST_Transform(ST_TileEnvelope(1,0,0), srid))
)
select ST_AsMVT(mvtgeom.*, 'zzz', 4096, 'geom') as mvt from mvtgeom;

from django.db import connection
from rest_framework.views import APIView
from rest_framework.response import Response

class MapView(APIView):

    def get(self, request, table, z, x, y):
        
        print(table, z, x, y,)
        table_name = table  #'zzz'
        
        # 将数据库的数据导出为geojson（建议不要太大，太大用 wms服务吧、或者mvt矢量切片）
        # sql = f"""select json_build_object('type', 'FeatureCollection', 'name', '{table_name}', 'features', json_agg(ST_ASGeoJSON(t.*)::json)) from {table_name} AS t """
        
        # 获取表的字段名称 列表
        # sql = f"""select column_name from information_schema.columns where table_name='{table_name}'"""  # where后面是string 不应被转成对象变量
        # 获取表的字段名称 字符串
        # sql = f"""select array_to_string(array(select column_name from information_schema.columns where table_name='{table_name}' and column_name != 'geom'), ',');"""
        # 动态矢量切片mvt   gid字段也可替换成前端传入的字段
        geom_name = 'geom'
        sql = f"""with mvtgeom as (
                select ST_AsMVTGeom(ST_Transform({geom_name}, 3857), ST_TileEnvelope({z},{x},{y})) as geom, gid
                from 
                {table_name}, 
                (select ST_SRID({geom_name}) as srid from {table_name} where {geom_name} is not null limit 1) a
                where
                ST_Intersects({geom_name}, ST_Transform(ST_TileEnvelope({z},{x},{y}), srid))
            )
            select ST_AsMVT(mvtgeom.*, '{table_name}', 4096, 'geom') as mvt from mvtgeom;"""
                
        print(sql)
        with connection.cursor() as cursor:
            cursor.execute(sql)
            results = cursor.fetchall()

        return Response(results)