Returns the geometry as a GeoJSON fragment
This does not return a complete GeoJSON document, only the geometry fragment. To construct a complete GeoJSON document or feature, look into using the DuckDB JSON extension in conjunction with this function. This function supports geometries with Z values, but not M values. M values are ignored.
SQL examples
SELECT ST_AsGeoJSON('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'::GEOMETRY);
-- {"type":"Polygon","coordinates":[[[0.0, 0.0], [0.0, 1.0], [1.0, 1.0], [1.0, 0.0], [0.0, 0.0]]]}
--
-- -- Convert a geometry into a full GeoJSON feature (requires the JSON extension to be loaded)
-- SELECT CAST({
-- type: 'Feature',
-- geometry: ST_AsGeoJSON(ST_Point(1, 2)),
-- properties: {
-- name: 'my_point'
-- }
-- } AS JSON);
-- {"type":"Feature","geometry":{"type":"Point","coordinates":[1.0, 2.0]},"properties":{"name":"my_point"}}