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”：“ Restaurant Sinaia”

但实际输出是 “ properties”：{“ f1”：6323，“ f2”：“ Restaurant Sinaia”

我阅读了row_to_json指令的规范，所以我决定更改最后一个row_to_json指令

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;

但是现在geojson还将几何字段作为属性检索。

我的意思是，在结果中，我可以看到以geojson格式设置的几何图形，然后又以PostGIS格式设置了几何图形（这第二个几何图形不是必需的，我可能会浪费掉），因此，如果第一个结果为1200Kb，第二个结果为2300Kb。

我该怎么办？

的任何替代方案

row_to_json((id, name)) As properties

或

row_to_json((lg)) As properties

我也尝试过类似的事情

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

和其他任何内容，但没有结果（只有SQL错误）

非常感谢您

Answer 1

您需要做的是，首先选择列，然后选择row_to_json。使用您的值，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

Answer 2

您可以使用ogr2ogr在控制台中执行此代码

cd C:\\OSGeo4W64\\bin && ogr2ogr -f "GeoJSON" C:\Users\Documents\nameFile.json "PG:dbname=nameBD schemas=NameSchema host='localhost' port='5432' user='postgres' password='**'" -sql "select * from public.tableName"

将PostGIS表（postgresql）转换为GeoJSON

2 个答案: