ST_AsGeoJSON(g [, max_dec_digits [, options]])

Generates a GeoJSON object from the geometry g. The object string has the connection character set and collation.

If any argument is NULL, the return value is NULL. If any non-NULL argument is invalid, an error occurs.

max_dec_digits, if specified, limits the number of decimal digits for coordinates and causes rounding of output. If not specified, this argument defaults to its maximum value of 2³² − 1. The minimum is 0.

options, if specified, is a bitmask. The following table shows the permitted flag values. If the geometry argument has an SRID of 0, no CRS object is produced even for those flag values that request one.

mysql> SELECT ST_AsGeoJSON(ST_GeomFromText('POINT(11.11111 12.22222)'),2);
+-------------------------------------------------------------+
| ST_AsGeoJSON(ST_GeomFromText('POINT(11.11111 12.22222)'),2) |
+-------------------------------------------------------------+
| {"type": "Point", "coordinates": [11.11, 12.22]}            |
+-------------------------------------------------------------+

ST_GeomFromGeoJSON(str [, options [, srid]])

Parses a string str representing a GeoJSON object and returns a geometry.

If any argument is NULL, the return value is NULL. If any non-NULL argument is invalid, an error occurs.

options, if given, describes how to handle GeoJSON documents that contain geometries with coordinate dimensions higher than 2. The following table shows the permitted options values.

options values of 2, 3, and 4 currently produce the same effect. If geometries with coordinate dimensions higher than 2 are supported in the future, these values will produce different effects.

The srid argument, if given, must be a 32-bit unsigned integer. If not given, the geometry return value has an SRID of 4326.

If srid refers to an undefined spatial reference system (SRS), an ER_SRS_NOT_FOUND error occurs.

For geographic SRS geometry arguments, if any argument has a longitude or latitude that is out of range, an error occurs:

Ranges shown are in degrees. If an SRS uses another unit, the range uses the corresponding values in its unit. The exact range limits deviate slightly due to floating-point arithmetic.

GeoJSON geometry, feature, and feature collection objects may have a crs property. The parsing function parses named CRS URNs in the urn:ogc:def:crs:EPSG::srid and EPSG:srid namespaces, but not CRSs given as link objects. Also, urn:ogc:def:crs:OGC:1.3:CRS84 is recognized as SRID 4326. If an object has a CRS that is not understood, an error occurs, with the exception that if the optional srid argument is given, any CRS is ignored even if it is invalid.

If a crs member that specifies an SRID different from the top-level object SRID is found at a lower level of the GeoJSON document, an ER_INVALID_GEOJSON_CRS_NOT_TOP_LEVEL error occurs.

As specified in the GeoJSON specification, parsing is case sensitive for the type member of the GeoJSON input (Point, LineString, and so forth). The specification is silent regarding case sensitivity for other parsing, which in MySQL is not case-sensitive.

This example shows the parsing result for a simple GeoJSON object:

mysql> SET @json = '{ "type": "Point", "coordinates": [102.0, 0.0]}';
mysql> SELECT ST_AsText(ST_GeomFromGeoJSON(@json));
+--------------------------------------+
| ST_AsText(ST_GeomFromGeoJSON(@json)) |
+--------------------------------------+
| POINT(102 0)                         |
+--------------------------------------+