[mapserver-users] About FILTER and FILTERITEM

[Rahkonen Jukka (Tike)]

Hi,

Thank you very much, Christy. By your example I made some tests and now filters like this work for me
FILTER (([WORKERS]>20000000) OR ("[STATE_FIPS]"="17"))

The secret element was the right syntax for string attributes  ("[STATE_FIPS]"="17").
Now when I know how it must be used I can find corresponding examples from the expression page of Mapserver documentation. Could someone explain shortly what is the difference between filter and expression? To me they seem to do pretty similar work.

-Jukka Rahkonen-

Christy Nieman wrote:

> You do not need to set both FILTERITEM and FILTER.  You can just set FILTER to
> an expression using as many attributes as you need. e.g.
> FILTER (( [POPULATION] < 500000 ) AND ("[DISPLAY]" == "1")). Just like you can
> have multiple attributes in a class EXPRESSION.
> 
> I think it's the section of the document that is key - the "MapServer Expressions"
> section talks about using FILTER and EXPRESSION in more complex logical
> expressions, where as the section you quoted is talking about basic string
> comparison.
> 
> Christy
> 
> On 14/05/14 08:03 AM, Rahkonen Jukka (Tike) wrote:
> > Hi,
> >
> >  From document page: http://mapserver.org/mapfile/expressions.html
> > "To use a string comparison for filtering a LAYER, both FILTERITEM and FILTER
> must be set. FILTERITEM is set to the attribute name. FILTER is set to the value
> for comparison. The same rule applies to CLASSITEM in the LAYER object and
> EXPRESSION in the CLASS object."
> >
> > That would mean that only one attribute from the data can be used for
> building a filter. Is this true or just old information living in the document?
> >
> > -Jukka Rahkonen-
> > _______________________________________________
> > mapserver-users mailing list
> > mapserver-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> 
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