[mapserver-users] About FILTER and FILTERITEM

[Steve.Toutant at inspq.qc.ca]

Filter is defined at the LAYER level while expression is defined at CLASS 
level.
So you could use expression for rendering filtered values....

using expression without filter means that you query all the data.






"Rahkonen Jukka  (Tike)" <jukka.rahkonen at mmmtike.fi>@lists.osgeo.org 
Envoyé par : mapserver-users-bounces at lists.osgeo.org
2014-05-14 09:05

A
"mapserver-users at lists.osgeo.org" <mapserver-users at lists.osgeo.org>
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Objet
Re: [mapserver-users] About FILTER and FILTERITEM








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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