postgresql - 将 PostGIS 表 (postgresql) 转换为 GeoJSON

Question

我访问了How to convert from PostgreSQL to GeoJSON format?中显示的问题

此 PostGIS SQL 将整个表转换为 GeoJSON 结果:

SELECT row_to_json(fc) AS geojson FROM 
(SELECT 'FeatureCollection' As type, array_to_json(array_agg(f))
As features FROM 
(SELECT 
'Feature' As type, 
ST_AsGeoJSON((lg.geometry),15,0)::json As geometry,
row_to_json((id, name)) As properties
FROM imposm3_restaurants As lg) As f ) As fc;

我发现在结果中，我们没有得到字段的名称。

我希望输出为 "properties":{"id":6323,"name":"锡纳亚餐厅"

但实际输出是 "properties":{"f1":6323,"f2":"锡纳亚餐厅"

看了row_to_json指令的规范，决定把最后一条row_to_json指令改掉

SELECT row_to_json(fc) AS geojson FROM 
(SELECT 'FeatureCollection' As type, array_to_json(array_agg(f))
As features FROM 
(SELECT 
'Feature' As type, 
ST_AsGeoJSON((lg.geometry),15,0)::json As geometry,
row_to_json((lg)) As properties
FROM imposm3_restaurants As lg) As f ) As fc;

但现在 geojson 还检索几何字段作为属性。

我的意思是，在结果中我可以看到以 geojson 格式和 PostGIS 格式格式化的几何图形(这第二个几何图形不是必需的，我可以浪费它)所以如果第一个结果是 1200Kb，第二个将是2300Kb。

我能做什么？任何替代品

row_to_json((id, name)) As properties

或

row_to_json((lg)) As properties

我也尝试过类似的东西

row_to_json(('id',lg.id ,'masa',lg.masa ,'parcela',lg.parcela)) As properties

和任何其他，但没有结果(只有 SQL 错误)

非常感谢

Answer 1

您需要做的是，首先选择您的列，然后选择 row_to_json。 根据您的值(value)观，这将给出以下示例:

SELECT
    row_to_json(fc)
FROM (
    SELECT
        'FeatureCollection' AS type
        , array_to_json(array_agg(f)) AS features
    FROM (
        SELECT
            'feature' AS type
            , ST_AsGeoJSON(geom)::json as geometry
            , (
                SELECT
                    row_to_json(t)
                FROM (
                    SELECT
                        id
                        , name
                    ) AS t
                ) AS properties
        FROM imposm3_restaurants
    ) AS f
) AS fc