[GRASS-user] Problem accessing GRASS from GRASS from PostgreSQL9.1/PostGIS2.0 via pg-python or plpythonu [SEC=UNCLASSIFIED]
Andrew MacIntyre
Andrew.MacIntyre at acma.gov.au
Wed Jul 18 17:53:30 PDT 2012
I suggest running a test script that reports sys.path to confirm that the actual Python module search path seen by the Postgres server's environment is as expected.
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Andrew MacIntyre Operations Branch
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> Message: 5
> Date: Wed, 18 Jul 2012 22:58:59 +1000
> From: Mark Wynter <mark at dimensionaledge.com>
> To: grass-user at lists.osgeo.org
> Subject: [GRASS-user] Problem accessing GRASS from
> PostgreSQL9.1/PostGIS2.0 via pg-python or plpythonu
> Message-ID: <4D8125BB-F64C-4D07-8D4B-
> 69C64060CB7E at dimensionaledge.com>
> Content-Type: text/plain; charset="utf-8"
>
> My requirement is to connect to GRASS from PostgreSQL9.1/PostGIS2.0 via
> the pg-python or plpythonu procedural language. I'm wondering whether I
> have a permissions issue?
>
> I'm running my stack on Ubuntu 12.04 LTS
> I've added the following environmental variables to /etc/bash.bashrc
> export GISBASE=/usr/local/grass-6.4.3svn
> export PATH=$PATH:$GISBASE/bin:$GISBASE/scripts:$GISBASE/lib
> export PYTHONPATH=${PYTHONPATH}:$GISBASE/etc/python/
> export PYTHONPATH=${PYTHONPATH}:$GISBASE/etc/python/grass
> export PYTHONPATH=${PYTHONPATH}:$GISBASE/etc/python/grass/script
> export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$GISBASE/lib
> export GIS_LOCK=$$
> export GISRC=$HOME/.grassrc6
>
> If I log out and log in again, the following environment variables are now
> available to the postgres user:
>
> ubuntu at ip-10-252-74-140:~$ sudo su postgres
> postgres at ip-10-252-74-140:/home/ubuntu$ echo $GISBASE
> /usr/local/grass-6.4.3svn
> postgres at ip-10-252-74-140:/home/ubuntu$ echo $PYTHONPATH
> :/usr/local/grass-6.4.3svn/etc/python/:/usr/local/grass-
> 6.4.3svn/etc/python/grass:/usr/local/grass-6.4.3svn/etc/python/grass/script
> postgres at ip-10-252-74-140:/home/ubuntu$ echo $HOME
> /var/lib/postgresql
>
>
> if I call the function "import grass.script as grass" from the python console,
> there is no error. All seems ok.
>
> postgres at ip-10-252-74-140:/$ python
> Python 2.7.3 (default, Apr 20 2012, 22:39:59)
> [GCC 4.6.3] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import grass.script as grass
> >>>
>
> If I now log into PostgreSQL/PostGIS via psql, and try to run the same
> command within in a postgresql plpythonu or pg-python function, I get the
> following error messages.
> psql -d test
>
> CREATE OR REPLACE FUNCTION pythontest() RETURNS text AS
> $$
> import grass.script as grass
> $$
> LANGUAGE 'plpythonu' VOLATILE;
>
> test=# select pythontest();
> ERROR: ImportError: No module named grass.script
> CONTEXT: Traceback (most recent call last):
> PL/Python function "pythontest", line 3, in <module>
> import grass.script as grass
> PL/Python function "pythontest"
> test=#
>
> I've also tried the pg-python language - in case it had something to do with
> plpythonu:
>
> CREATE OR REPLACE FUNCTION pgpython_test()
> RETURNS text LANGUAGE python AS
> $python$
> import Postgres
> import grass.script as grass
> def main():
> return ("Hello World")
> $python$;
>
>
> test=# select pgpython_test();
> ERROR: could not load Python function's module object
> CONTEXT: [exception from Python]
> Traceback (most recent call last):
> File "public.pgpython_test()", line 3, in <module>
> ImportError: No module named grass.script
>
> [public.pgpython_test() while loading function module]
> test=#
>
> I can however access GRASS from PostgreSQL9.1/PostGIS2.0 via pl/r and R.
> For example, this function works...
> CREATE OR REPLACE FUNCTION generate_viewshed() RETURNS text as
> $$
> library(spgrass6)
> #initialise GRASS.
> initGRASS(gisBase = ?/usr/local/grass-6.4.3svn/?, home = tempdir(),
> gisDbase = ?/usr/local/share/grassdata/?, location =
> ?aust_dem_1sec_wgs84?, mapset = ?postgres?, SG=?aust_dem_1sec?,
> override = TRUE)
> #define the computational region for the analysis ? limiting the region to an
> area slightly greater than the max_distance from the observation point.
> execGRASS(?g.region?, parameters = list(n=?-34.9759927736275?, s=?-
> 34.9985728860995?, e=?138.641896696527?, w=?138.619947232807?,
> align=?aust_dem_1sec?))
> #run the viewshed module ? all of these parameters can be set dynamically
> and parsed as plr function arguments ? the output is a raster file.
> execGRASS(?r.viewshed?, parameters = list(input = ?aust_dem_1sec?,
> output = ?viewshed_raster?, coordinate = ?138.630922,-34.987283?,
> obs_elev = 25, max_dist = 1000), flags = c(?b?, ?overwrite?))
> #convert the raster output to a vector.
> execGRASS(?r.to.vect?, parameters = list(input = ?viewshed_raster?, output
> = ?viewshed_vector?, feature = ?area?), flags = c(?overwrite?))
> #write the vector data back to PostGIS.
> execGRASS(?v.out.ogr?, parameters = list(input = ?viewshed_vector?, dsn =
> ?PG:host=localhost dbname=test user=postgres password=password?,
> olayer = ?viewshed_vector?, format = ?PostgreSQL?, type = ?area?), flags =
> c(?c?))
> $$
> LANGUAGE ?plr?;
>
> In terms of GRASS permissions...
> postgres at ip-10-252-74-140:/home/ubuntu$ vi $HOME/.grassrc6
> GISDBASE: /usr/local/share/grassdata
> LOCATION_NAME: aust_dem_1sec_wgs84
> MAPSET: postgres
> GRASS_GUI: text
> ~
>
> This is as far as I've got and need some help to connect to GRASS from
> PostgeSQL/PostGIS via python (as an alternative to pl/r).
> Is there something obvious I have missed? Could someone please guide me
> through to a solution.
>
> With thanks and regards
>
> Mark
>
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