Aman, Thanks for the informative post. Could you put the relevant parts and your example file into the issue tracker at
http://trac.osgeo.org/postgis so we have a record of it? I can see the benefit in handling data in the "way others do" for maximum ease of use. Yours, Paul On Fri, Aug 13, 2010 at 6:13 PM, Aman Verma <aman.ve...@mcgill.ca> wrote: > Hi everybody, > > This is my first post to the list. Please let me know (flame) if this is not > a suitable place to post. > > If you use shp2pgsql to upload a shapefile with an attribute table that has a > malformed integer (like a letter), shp2pgsql will not correct it, and the > upload will fail. > > Normally, I would view this as 'expected behaviour' (garbage in, garbage > out). However, I have two reasons to believe that shp2pgsql should do the > correction: > > 1) ArcGIS, and other software that read the xBase format (DBF), interpret > such malformed integers as 0. There seem to be a lot of shape files floating > around that have malformed integers in them, precisely because they appear to > be working. Users may have a difficult time understanding why shp2pgsql keeps > trying to upload 'g' when all they can see is '0'. > > 2) shapelib, the library that shp2pgsql uses to read the shapefiles, will > also interpret malformed integers as zeroes, provided the appropriate > function is used. (http://shapelib.maptools.org/dbf_api.html - see > DBFReadIntegerAttribute). I assume this decision was made to conform to how > Arc handles them. > > Although shp2pgsql uses the shapelib library to read shape files, it opts to > use the DBFReadStringAttribute function to read integers and doubles (see the > ShpLoaderGenerateSQLRowStatement function about line 1537 in the current > source shp2pgsql-core.c). I can't really understand why, when there is a > perfectly good integer reading function available. > > I suggest that the code for shp2pgsql be changed to use the > DBFReadIntegerAttribute function for integers, and the DBFReadDoubleAttribute > function for doubles. If that is unappealing for other reasons, perhaps the > current code could be modified to detect when the attribute is not a number, > and convert it to a zero. Alternatively, if this is not desired as default > behaviour an optional switch on the command line would be helpful to convert > malformed integers. > > You can find an example of a shapefile with a malformed integer here: > > http://aman.koumbit.org/arret2.zip > > This file contains a shapefile that has a single point. The point has two > attributes, ID and VANDAL. Both are integers. The VANDAL attribute is set to > the letter 'g'. ArcGIS, and other DBF viewing software, interpret this as 0. > > I am using the 1.5 (RCSID: $Id: shp2pgsql-core.h 5098 2010-01-04 05:47:04Z > pramsey) release of shp2pgsql, on the Windows platform. > > Thanks everybody, > aman > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
