The SE_PointFromBSON() function

The SE_PointFromBson() function takes a bson value with spatial data following the GeoJSON specification and a JSON path in a VARCHAR string, and returns an ST_Point object.

Syntax

create function SE_PointFromBSON(bson,varchar(255))
returns ST_Point

Return type

ST_Point

Example

The city engineer wants to know the “Point” of a city, an array of at least two coordinate values of the position of the city. The first coordinate is longitude in the range of -180.0 and 180, the second value is latitude from -90 and 90.

The following code inserts one row for GeoJSON geometry type Point.

-- create a table of bson value containing GeoJson spatial values under the city tag
create table bson_tab (pid serial, geometry bson, type varchar(16));
Table created.

-- insert values for Point
insert into bson_tab values(0, ('{
		"city":{
			"type":"Point",
			"coordinates" : [3, 2]
		}
	 }'::json)::bson,
	'Point');
1 row(s) inserted.

The query selects a point value from the table by using SE_PointFromBSON.

select pid,se_pointfrombson(geometry,'city') from bson_tab where type = 'Point' ;

This is the result.

pid           1
(expression)  4326 POINT (3 2) 

1 row(s) retrieved.