problem with expression: null values in table

[Bart van den Eijnden]

Hi Umberto,

thanks for the explanation.

So this means with shapefiles in 5.0 null values would fall into the
category of ([mycolumn] = 0) ? That seems almost even worse to me than an
error ....

Mapserver really needs the concept of null values, but I can imagine this
would require quite a bit of work ...

Best regards,
Bart

On 10/8/07, Umberto Nicoletti <umberto.nicoletti at gmail.com> wrote:
>
> Probably when the column is null it is evaluated by OGR to the empty
> string and the expression (after replacing [HINDERCATEGORIE] with '')
> becomes ' = 1' which is invalid.
>
> Just a side note: starting with mapserver 5 the shapefile provider
> will return 0 for null numeric columns and '' for null strings.
>
> Umberto
>
> On 10/8/07, Bart van den Eijnden <bartvde at gmail.com> wrote:
> > Hi list,
> >
> > I am posting this problem here since I don't know if it is an OGR
> problem or
> > a Mapserver problem.
> >
> > Using Mapserver 5.0 and GDAL 1.4.1 we have an Oracle table that only
> > contains null values for an integer column called HINDERCATEGORIE.
> >
> > The expression used in Mapserver is:
> >
> > EXPRESSION ([HINDERCATEGORIE] = 1)
> >
> > which will result in:
> >
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> >  msyyparse(): Expression parser error. parse error
> >
> > [bart at hades rwsnl]$ shp2img -m topografie.map -all_debug 10 -l
> > vaarwegwerkzaamheid_live -o /tmp/bla.png
> > msOGRFileOpen(vaarwegwerkzaamheid_live.ovf)...
> > OGROPen(/data/OGC_UMN_services/rwsnl/./vaarwegwerkzaamheid_live.ovf)
> > msyyparse(): Expression parser error. parse error
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> > msyyparse(): Expression parser error. parse error
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> > msyyparse(): Expression parser error. parse error
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> > msyyparse(): Expression parser error. parse error
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> > msyyparse(): Expression parser error. parse error
> > msEvalExpression: Expression parser error. Failed to parse
> expression:  = 1
> > msOGRLayerClose(vaarwegwerkzaamheid_live.ovf).
> >
> msOGRFileClose(/data/OGC_UMN_services/rwsnl/./vaarwegwerkzaamheid_live.ovf,0).
> > msDrawMap(): Layer 3 (vaarwegwerkzaamheid_live), 0.761s
> > msDrawLabelCacheGD(): labelcache_map_edge_buffer = -10
> > msDrawMap(): Drawing Label Cache, 0.005s
> > msDrawMap() total time: 0.781s
> >
> > The layer definition is:
> >
> >   LAYER
> >     NAME "vaarwegwerkzaamheid_live"
> >     TYPE POINT
> >     CONNECTIONTYPE OGR
> >     CONNECTION "vaarwegwerkzaamheid_live.ovf"
> >     DATA "vaarwegwerkzaamheid"
> >     PROCESSING "CLOSE_CONNECTION=DEFER"
> >     PROJECTION
> >       "init=epsg:28992"
> >     END
> >     METADATA
> >       "WMS_TITLE" "Vaarwegwerkzaamheden - staging omgeving"
> >     END
> >     CLASS
> >       NAME "Unknown"
> >       EXPRESSION ([HINDERCATEGORIE] = 1)
> >       STYLE
> >         ANGLE 360
> >         COLOR 0 0 0
> >         OPACITY 100
> >         SYMBOL "wegwerkzaamheid_3"
> >       END
> >     END
> >   END
> >
> > Best regards,
> > Bart
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/mapserver-dev/attachments/20071008/798db73f/attachment.html