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Currently I fetch polygons from a database table using ST_AsText(). The results are in text format, like the following.

POLYGON((84 104,212 48,321 122,243 179,275 238,131 240,84 104))

I am not quite sure if ST_AsText() and string manipulation is the way to go for performant polygon reading. Is there another way to fetch the points?

How can I get all points of a polygon as an array in PHP?

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JSON might be a better solution postgis.org/docs/ST_AsGeoJSON.html is fast with openlayers – Mapperz♦ May 8 at 14:23
Thanks, that is a great option since I can directly forward that to Leaflet. If you would write an answer, I'll mark it as accepted. – danijar May 8 at 14:59
Posted a longer answer basis on @danijar feedback. – Mapperz♦ May 8 at 15:07

1 Answer

up vote 1 down vote accepted

For current method ST_AsText() I suggest that you request GeoJSON instead this can be requested from PostGIS natively

Example:

SELECT ST_AsGeoJSON(the_geom) from fe_edges limit 1;
                       st_asgeojson
-----------------------------------------------------------------------------------------------------------

{"type":"MultiLineString","coordinates":[[[-89.734634999999997,31.492072000000000],
[-89.734955999999997,31.492237999999997]]]}
(1 row)
--3d point

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

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

in response to JSON might be a better solution postgis.org/docs/ST_AsGeoJSON.html is fast with openlayers

Full official documentation: http://www.postgis.org/docs/ST_AsGeoJSON.html

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I have one related question. It there some kind of reverse function? Would be really helpful if I could store from JSON by something like ST_GeomFromGeoJSON(). – danijar May 8 at 15:16
postgis.org/documentation/manual-svn/ST_GeomFromGeoJSON.html will take GeoJSON and import it into PostGIS – Mapperz♦ May 8 at 15:19
I must have overseen it, thanks! – danijar May 8 at 16:12

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