将PostGIS表(PostgreSQL)转换为Geojson

Question

我访问了如何从postgresql转换为geojson格式的问题？

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，"名称"："餐厅Sinaia"

但是实际输出是 " properties"：{" f1"：6323，" f2"："餐厅Sinaia"

我阅读了row_to_json指令的规范，所以我决定更改最后的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;

，但现在Geojson也将几何字段作为属性。

我的意思是，在结果中，我可以看到以geojson格式形成的几何形状，并以gis postgis格式(不需要第二几何形状，我可以浪费(，所以如果第一个结果是1200kb，第二个结果将围绕2300kb。

我该怎么办？

的任何替代品

row_to_json((id, name)) As properties

或

row_to_json((lg)) As properties

我也尝试了

之类的事情

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

和其他任何人，但没有结果(仅SQL错误(

非常感谢

Answer 1

您需要做的是首先选择列，然后选择row_to_json此选择。以您的价值观，这将提供以下示例：

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

您可以在控制台中使用OGR2OGR执行此代码

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