Name

ST_AsGeoJSON — Return the geometry as a GeoJSON element.

Synopsis

text ST_AsGeoJSON(record feature, text geomcolumnname, integer maxdecimaldigits=15, boolean prettyprint=false);

text ST_AsGeoJSON(geometry geom, integer maxdecimaldigits=15, integer options=0);

text ST_AsGeoJSON(geography geog, integer maxdecimaldigits=15, integer options=0);

Description

Return the geometry as a GeoJSON "geometry" object, or the row as a GeoJSON "feature" object. (Cf GeoJSON specifications RFC 7946). 2D and 3D Geometries are both supported. GeoJSON only support SFS 1.1 geometry types (no curve support for example).

The maxdecimaldigits argument may be used to reduce the maximum number of decimal places used in output (defaults to 15). If you are using EPSG:4326 and are outputting the geometry only for display, maxdecimaldigits=6 can be a good choice for many maps.

The options argument could be used to add BBOX or CRS in GeoJSON output:

  • 0: means no option (default value)

  • 1: GeoJSON BBOX

  • 2: GeoJSON Short CRS (e.g EPSG:4326)

  • 4: GeoJSON Long CRS (e.g urn:ogc:def:crs:EPSG::4326)

Availability: 1.3.4

Availability: 1.5.0 geography support was introduced.

Changed: 2.0.0 support default args and named args.

Changed: 3.0.0 support records as input

This function supports 3d and will not drop the z-index.

Examples

GeoJSON format is popular among web mapping frameworks.

You can test and view your GeoJSON data online on geojson.io.

SELECT ST_AsGeoJSON(t.*)
FROM (VALUES
  (1, 'one', 'POINT(1 1)'::geometry),
  (2, 'two', 'POINT(2 2)'),
  (3, 'three', 'POINT(3 3)'))
AS t(id, name, geom);
                                                  st_asgeojson
-----------------------------------------------------------------------------------------------------------------
 {"type": "Feature", "geometry": {"type":"Point","coordinates":[1,1]}, "properties": {"id": 1, "name": "one"}}
 {"type": "Feature", "geometry": {"type":"Point","coordinates":[2,2]}, "properties": {"id": 2, "name": "two"}}
 {"type": "Feature", "geometry": {"type":"Point","coordinates":[3,3]}, "properties": {"id": 3, "name": "three"}}
SELECT ST_AsGeoJSON(geom) from fe_edges limit 1;
					   st_asgeojson
-----------------------------------------------------------------------------------------------------------

{"type":"MultiLineString","coordinates":[[[-89.734634999999997,31.492072000000000],
[-89.734955999999997,31.492237999999997]]]}
(1 row)

You can also use it with 3D geometries:

SELECT ST_AsGeoJSON('LINESTRING(1 2 3, 4 5 6)');

st_asgeojson
-----------------------------------------------------------------------------------------
 {"type":"LineString","coordinates":[[1,2,3],[4,5,6]]}

See Also

ST_GeomFromGeoJSON, ST_AsMVT, ST_AsGeobuf