Need Path in the form of Lat,long using pgrouting

Question

I am using this query for finding the path using postgresql , postgis, pgrouting, postgis_topology using nodejs

client.query(
"WITH dijkstra AS (
  SELECT * 
  FROM pgr_dijkstra('SELECT id,source,target,distance AS cost 
     FROM edges_noded',230965,3338,false)) 
 SELECT seq, 
   CASE WHEN dijkstra.node = edges_noded.source THEN edges_noded.the_geom 
   ELSE ST_Reverse(edges_noded.the_geom) END AS route_geom 
 FROM dijkstra JOIN edges_noded ON(edge = id) 
 ORDER BY seq",(err,res)=>{ var data = res.rows;})

now problem is that this query returns two columns which is

I think route_geom column in above above image has a information of path.

How can I modified the above query to get path in the form of latitude and longitude.

I need the complete path in the form of latitude and longitude.

Jim Jones · Accepted Answer · 2020-01-06T16:05:09.160

If I understood you correctly, you just need to convert the already existing coordinates to a format that your application can read. There are many formats you can get directly from PostGIS. Here a few that might interest you:

Data sample

CREATE TEMPORARY TABLE t (seq INT, the_geom GEOMETRY);
INSERT INTO t VALUES (1,'POINT(1 2)'),(2,'POINT(2 3)');

Geometries in the PostGIS geometry format - as you've been doing so far.

SELECT seq, the_geom FROM t;
 seq |                  the_geom                  
-----+--------------------------------------------
   1 | 0101000000000000000000F03F0000000000000040
   2 | 010100000000000000000000400000000000000840
(2 Zeilen)

Retrieving data as latitude and longitude in separated columns - ST_X, ST_Y

SELECT seq, ST_X(the_geom), ST_Y(the_geom) FROM t;
 seq | st_x | st_y 
-----+------+------
   1 |    1 |    2
   2 |    2 |    3
(2 Zeilen)

As WKT - ST_AsText

SELECT seq, ST_AsText(the_geom) FROM t;
 seq | st_astext  
-----+------------
   1 | POINT(1 2)
   2 | POINT(2 3)
(2 Zeilen)

.. or GeoJSON - ST_AsGeoJSON

SELECT seq, ST_AsGeoJSON(the_geom) FROM t;
 seq |             st_asgeojson             
-----+--------------------------------------
   1 | {"type":"Point","coordinates":[1,2]}
   2 | {"type":"Point","coordinates":[2,3]}
(2 Zeilen)

So your CTE will most likely look like this

WITH dijkstra AS (
  SELECT *
  FROM pgr_dijkstra('SELECT id,source,target,distance AS cost 
    FROM edges_noded',230965,3338,false)) 
SELECT seq, 
  CASE WHEN dijkstra.node = edges_noded.source THEN ST_X(edges_noded.the_geom)
  ELSE ST_X(ST_Reverse(edges_noded.the_geom)) END AS route_geom_x,
  CASE WHEN dijkstra.node = edges_noded.source THEN ST_Y(edges_noded.the_geom)
  ELSE ST_Y(ST_Reverse(edges_noded.the_geom)) END AS route_geom_y 
FROM dijkstra JOIN edges_noded ON(edge = id) 
ORDER BY seq

Thanks #Jim Jones for your detailed answer – M.HUSSAIN Jan 07 '20 at 05:08 — M.HUSSAIN, Jan 07 '20 at 05:08

Need Path in the form of Lat,long using pgrouting

1 Answers1