I am wondering whether it actually is an error. My assumption was that
<ogc:Literal> is always a string.
The method, strSubstring (string:String, begin:Integer, end:Integer)
clearly wants a string and two integers. So, you must give these types to
that method.
Hence, the correct form would be:
<sld:Label>
<ogc:Function name="strSubstring">
<ogc:PropertyName>STATIONNAME</ogc:PropertyName> //String - param[0]
<ogc:Function name="parseInt"> //1. Int –
param[1]
<ogc:Literal>0</ogc:Literal>
</ogc:Function>
<ogc:Function name="parseInt"> //2. Int –
param[2]
<ogc:Literal>3</ogc:Literal>
</ogc:Function>
</ogc:Function>
</sld:Label>
That works for me and obviously for Ákos.
If I wrap the first parseInt function into a <ogc:Literal>
Like below I get:
<sld:Label>
<ogc:Function name="strSubstring">
<ogc:PropertyName>STATIONNAME</ogc:PropertyName>
/<ogc:Literal>/<ogc:Function name="parseInt">
<ogc:Literal>0</ogc:Literal>
</ogc:Function> /</ogc:Literal>/
<ogc:Function name="parseInt">
<ogc:Literal>3</ogc:Literal>
</ogc:Function>
</ogc:Function>
</sld:Label>
java.lang.IllegalArgumentException: Filter Function problem for function
strSubstring argument #1 - expected type int at
org.geotools.filter.function.FilterFunction_strSubstring.evaluate(FilterFunction_strSubstring.java:55).
Fair enough, that is what I expect, because my integer is converted again
into a string.
Now when I put an AA instead of a number in there:
<sld:Label>
<ogc:Function name="strSubstring">
<ogc:PropertyName>STATIONNAME</ogc:PropertyName>
<ogc:Function name="parseInt">
<ogc:Literal>AA</ogc:Literal>
</ogc:Function>
<ogc:Function name="parseInt">
<ogc:Literal>3</ogc:Literal>
</ogc:Function>
</ogc:Function>
</sld:Label>
Geoserver tries to think for me and puts a 0 in and displays the label. Well
to assume that everything for the first parameter, which cannot be read or
converted, is position 0, is fine.
Now, trying to trick Geoserver, because it cannot make assumption about the
end of the string gets the following result:
<sld:Label>
<ogc:Function name="strSubstring">
<ogc:PropertyName>STATIONNAME</ogc:PropertyName>
<ogc:Function name="parseInt">
<ogc:Literal>0</ogc:Literal>
</ogc:Function>
<ogc:Function name="parseInt">
<ogc:Literal>BB</ogc:Literal>
</ogc:Function>
</ogc:Function>
</sld:Label>
This goes through the validation but at Submit I get the following error:
14 Nov 11:05:53 WARN [catalog.impl] - Catalog listener threw exception
handling event. java.lang.NullPointerException at
org.geoserver.gwc.layer.CatalogConfiguration.getLayerInfosFor(CatalogConfiguration.java:413)
Nevertheless the style is submitted successfully, however, the map displays
without label.
My point is: I think this is actually enough, however, I would like to see
an error message from parseInt or other functions, because if I write AA in
an SLD, it is obvious, that this is no int. If the value comes from a
database it is not. The implicit conversion would rather confuse me and
there is no way to check beforehand if the string value to be converted is
correct if it is a varialble. Furthermore, the implicit conversion from
literal/String into the right Java type needs to be done either for all
methods or for none. As these methods will increase. I am pretty sure the
conversion will be forgotten for the odd method to be added in the future
and that is bad.
I think I would prefer an error message from parseInt instead of nothing and
going through the documentation and change the wording that it becomes clear
what type a function passes back and may be adding a few examples, so that
people understand that types matter when using methods.
-----
____________________________
Dr Christian Maul
Project Manager
Information Services Branch
Department of Sustainability and Environment
Level13, Marland House, 570 Bourke Street
Melbourne 3000
PO Box 500, East Melbourne Vic 3002
Telephone: +61-3-8636 2325
Telefax: +61-3-8636 2813
--
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http://osgeo-org.1560.n6.nabble.com/Problem-with-strSubstring-function-in-SLD-tp5015967p5016135.html
Sent from the GeoServer - User mailing list archive at Nabble.com.
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