[mapserver-users] mapscript Perl/Python: DBF

[Lowell.Filak]

Is it possible to generate & use a unique name for the new shape/dbffile?
This should eliminate a name conflict that could be causing the crash.
Lowell F.

On Tue, 23 Jul 2002, Michael Schulz wrote:

> Hi List,
>
> i have a python-mapscript script that queries a database, queries for
> each returned value a layer (via filteritem/filter) and then retrieves
> the resulting shapeOj and puts it in a new shapefileObj. the dbf-file
> for the new shapefileObj is also generated with msDBFCreate, then twqo
> fields are created and later records are added to the dbf, finally the
> dbf file are closed.
>
> The problem is now, that this sometimes does not work and it crashes
> with a segmentation fault. It seems, this script is working when the
> dbf-files that are to be created do not exist in the specified
> directory. So i build a method that prior to creating the shape and dfb
> files looks in the directory and if present deletes the shp/shp/dbf
> file. But still the script crashes- if i do it manually it works.
>
> Can somebody give me a hint, i if have to do something special with the
> DBFInfoObj's or sth similar: That would be great.
>
> Cheers, Michael
>
> P.S.: the source code of the script:
>
> --snip
>
>   newshpname = '/var/www/plz_veranst'
>   newshp = shapefileObj(newshpname,MS_SHAPEFILE_POINT)
>   newshpdbf = msDBFCreate(newshpname+'.dbf')
>   msDBFAddField(newshpdbf,'PLZ',0,5,0)
>   msDBFAddField(newshpdbf,'NAME',0,35,0)
>
>   # Query existing plz-points and copy values to new plz_veranst
>   plzdbf = msDBFOpen('/var/www/plz_points.dbf',"rb")
>   plzmap = mapObj('/var/www/test.map')
>   plzlayer = plzmap.getLayerByName('orte_gesamt')
>   plzlayer.filteritem="PLZ"
>   plzshp = shapefileObj('/var/www/plz_points',-1)
>   count=0
>   for vlist_item in vlist: # vlist is a list of integers
>     plzlayer = plzmap.getLayerByName('orte_gesamt')
>     plzlayer.filteritem="PLZ"
>     plzlayer.setFilter("\"%d\"" % int(vlist_item))
>     plzlayer.queryByAttributes(plzmap,MS_SINGLE)
>     if plzlayer.resultcache.numresults == 1:
>       r = plzlayer.getResult(0)
>       ptshp = shapeObj(-1)
>       plzshp.get(r.shapeindex, ptshp)
>       name = msDBFReadStringAttribute(plzdbf,r.shapeindex,2)
>       newshp.add(ptshp)
>       msDBFWriteStringAttribute(newshpdbf, count, 0, vlist_item)
>       msDBFWriteStringAttribute(newshpdbf, count, 1, name)
>       count=count+1
>   msDBFClose(plzdbf)
>   msDBFClose(newshpdbf)
>
> --snip
>
> --
> -----------------------------------------------------------
> Michael Schulz                                in medias res
> Dipl.-Geologe                              Gesellschaft für
>                                 Informationstechnologie mbH
>                              Sautierstr. 38, 79104 Freiburg
>                                      0761 55695-95 (Fax 96)
> mschulz at webgis.de                             www.webgis.de
>
>