[mapserver-users] Problem with Python MapScript queryByRect

[Just van den Broecke]

I got somewhat further: it appears I get a SEGFAULT when calling any 
MapScript query() method. This is also what FastCGI receives (signal 11).

For example, bash-ing into the Docker Container and execute MapScript 
Python:

$ python
Python 2.7.16 (default, Oct 10 2019, 22:02:15)
[GCC 8.3.0] on linux2
 >>> import mapscript
 >>> map = mapscript.mapObj('/app1/config/mapserver/app1.map')
 >>> layer = map.getLayerByName('nlpubs')
 >>> layer.name
'nlpubs'
 >>> len(layer.metadata)
0
 >>> res = layer.queryByAttributes(map, 'Name', 'Lef', 
mapscript.MS_MULTIPLE)
Segmentation fault

But getting number of Features is ok:
 >>> layer.getNumFeatures()
GNM: GNMRegisterAllInternal
GNM: RegisterGNMFile
GNM: RegisterGNMdatabase
GDAL: GDALOpen(/app1/data/pubs, this=0x557ace611b90) succeeds as ESRI 
Shapefile.
Shape: DBF Codepage = LDID/87 for /app1/data/pubs/osm-nl-pub.shp
Shape: Treating as encoding 'ISO-8859-1'.
GDAL: GDALClose(/app1/data/pubs, this=0x557ace611b90)
2864

The LAYER def is
LAYER
     NAME nlpubs
     STATUS default
     TYPE POINT
     PROJECTION
       "init=epsg:4326"
     END

     METADATA
         "wfs_title"         "NL Pubs from OSM POIs"
         "wfs_version" 	"1.1.0"
         "wfs_extent" 	"4 50 6 54"
         "wfs_bbox_extended"     "true"
         "wfs_enable_request"    "*"
         "wfs_srs" 		"epsg:4326 epsg:3857 epsg:900913"
         "wfs_include_items"     "all"
         "gml_include_items"     "all"
         "gml_geometries"        "geom"
         "wms_title"             "NL Pubs from OSM POIs"
         "wms_srs" 		"epsg:4326 epsg:3857 epsg:900913"
         "wms_extent" 	"4 50 6 54"
         "wms_feature_info_mime_type" "text/xml"
         "mapglow_feat_density"	 "0.002"
    END

     CONNECTIONTYPE OGR
     CONNECTION "/app1/data/pubs"
     DATA "osm-nl-pub"
     TEMPLATE "/app1/config/mapserver/template.html"

     CLASS
       NAME "osm-nl-pub"
       STYLE
         COLOR 0 102 204
         SYMBOL "circle"
         SIZE 10
       END
     END
END

Data is a shapefile, but GeoJSON also fails. Also strange that 
layer.metadata is empty. Like said when I delegate any incoming OWS req 
to map.OWSDispatch() I get proper results for all WMS requests, in 
particular GetMap with styled output.
The base Dockerfile used is at:
https://github.com/PDOK/mapserver-docker/blob/master/Dockerfile from
which I derived my Dockerfile:
https://github.com/justb4/mapglow/blob/master/Dockerfile

Maybe there is some mismatch in lib versions?

Again thanks. Best,

Just van den Broecke

On 26-06-20 17:55, Just van den Broecke wrote:
> Hi,
> 
> I am reviving a Python 2 MapServer MapScript app that used to work 7 
> years ago (and still is in old deployment) but stuck in some MapScript 
> calls that fail but also throw no Exceptions.
> 
> Purpose of the app "MapGlow" [1] is to generate a WMS-heatmap triggered 
> by specific STYLE parameters. When no heatmap STYLE is requested 
> requests are delegated to map_file.OWSDispatch() etc. The latter works 
> fine so the overall setup/stack/mapfile is working. Using MS 7.6.0 in 
> Docker (compose) with Lighttp, FastCGI, WSGI, flup.
> 
> It is only when  layerObj.queryByRect() is called, a HTTP 500 is 
> returned after a FastCGI hard error, no means to catch an Exception. The 
> passed MapFile and Rect objects seem ok. Also I noticed that 
> layerObj.metadata had 0 items. I can see that I have proper SWIG objects 
> like
> <mapscript.layerObj; proxy of <Swig Object of type 'layerObj *' at 
> 0x7fded06b1de0> >
> If only I could get a hint, a MapFile setting, maybe some log output or 
> debug flag I can set? The WIP is on GH, I can point at the failing line 
> [2] but the code is
> quite involved (mind, my first Python 7-9 years ago):
> 
> [1] https://github.com/justb4/mapglow
> [2] 
> https://github.com/justb4/mapglow/blob/master/app1/wms/mapglow_ms.py#L249
> 
> Thanks for any help,
> 
> Just van den Broecke
> The Netherlands
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