[GIS] Using gdal.Warp cutlineSQL option in python

gdalpostgispython

I want to use the gdal.Warp method with python (doc). I have seen a cutlineSQL option which would be nice for my case since cutlines are stored in a PostGIS table but I can not find the syntax for this parameter.

How to tell gdal which database connection to use?

Or maybe I misunderstood the meaning of this parameter?

How to provide a cutline to Warp method then?

option not presented in the warp tutorial neither.

What I have so far : 

from osgeo import gdal
from osgeo.gdalconst import GA_ReadOnly

# input dataset
dataset = gdal.OpenShared(path, GA_ReadOnly)
raster = dataset.GetRasterBand(1)

# warp options
db_conn = """PG:"host=xx.xx.xx.xx port=5432 user='xxxx' password='xxxx' dbname='xxxx'" """
warp_opts = gdal.WarpOptions(
        format="GTiff",
        cutlineDSName=db_conn,
        cutlineSQL="SELECT cutline FROM table WHERE id_1",
        cropToCutline=True,
    )

# warp
res = gdal.Warp("test.tif",
                 raster,
                 options=warp_opts,
             )

Producing the error : 

ERROR 1: PQconnectdb failed.
invalid connection option ""host"

ERROR 1: Cannot open PG:"host=xx.xx.xx.xx port=5432 user='xxx' password=XXXXXXXXXX dbname='xxxx'" .

While ogrinfo with the same paramters is working.

If I try to remove some quotes in db_conn like this : 

db_conn = "PG:host=xx.xx.xx.xx port=5432 user='xxxx' password='xxxx' dbname='xxxx'"

I end up with a seg fault…

Best Answer

Ok, after a lot of efforts :-p, I ended up with a working script:

from osgeo import gdal

db_conn = "PG:host=xx.xx.xx.xx port=5432 user='xxxx' password='xxxx' dbname='xxxx'"
warp_opts = gdal.WarpOptions(
    format="GTiff",
    cutlineDSName=db_conn,
    cutlineSQL="SELECT cutline FROM table WHERE id=1",
    cropToCutline=True,
)

res = gdal.Warp("test.tif",
                 path,
                 options=warp_opts,
             )
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