[QGIS-Developer] QGIS-Server: filter by categories in an OGC compatible way

[pblottiere]

Hi Andreas,


> Can you point me to an example how to create a valid GetMap request
with an SLD submitted?


There's a basic example in unit tests:
https://github.com/qgis/QGIS/blob/master/tests/src/python/test_qgsserver_wms_getmap.py#L1309-L1325


Regards,

Paul


On 4/9/19 4:14 PM, Andreas Neumann wrote:
>
> Hi,
>
> I did some test:
>
> Here is a long URL with the SLD (originally sent by QGIS server,
> stripped away some RULES manually) and sending it back in a GetMap
> request:
>
> https://services.geo.zg.ch/ows-oereb/Grundwasserschutz?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=2682932,1225299,2684213,1226054&CRS=EPSG:2056&WIDTH=1615&HEIGHT=952&LAYERS=ch.zg.grundwasserschutz.gwszonen&STYLES=&FORMAT=image/png&DPI=96&MAP_RESOLUTION=96&FORMAT_OPTIONS=dpi:96&TRANSPARENT=TRUE&SLD=%3CStyledLayerDescriptor+xmlns%3D%22http%3A%2F%2Fwww.opengis.net%2Fsld%22+xmlns%3Axlink%3D%22http%3A%2F%2Fwww.w3.org%2F1999%2Fxlink%22+xmlns%3Axsi%3D%22http%3A%2F%2Fwww.w3.org%2F2001%2FXMLSchema-instance%22+xsi%3AschemaLocation%3D%22http%3A%2F%2Fwww.opengis.net%2Fsld+http%3A%2F%2Fschemas.opengis.net%2Fsld%2F1.1.0%2FStyledLayerDescriptor.xsd%22+xmlns%3Ase%3D%22http%3A%2F%2Fwww.opengis.net%2Fse%22+version%3D%221.1.0%22+xmlns%3Aogc%3D%22http%3A%2F%2Fwww.opengis.net%2Fogc%22%3E%0D%0A+%3CNamedLayer%3E%0D%0A++%3Cse%3AName%3Ech.zg.grundwasserschutz.gwszonen%3C%2Fse%3AName%3E%0D%0A++%3CUserStyle%3E%0D%0A+++%3Cse%3AName%3Edefault%3C%2Fse%3AName%3E%0D%0A+++%3Cse%3AFeatureTypeStyle%3E%0D%0A++++%3Cse%3ARule%3E%0D%0A+++++%3Cse%3AName%3EGrundwasserschutzzone+S1%3C%2Fse%3AName%3E%0D%0A+++++%3Cse%3ADescription%3E%0D%0A++++++%3Cse%3ATitle%3EGrundwasserschutzzone+S1%3C%2Fse%3ATitle%3E%0D%0A+++++%3C%2Fse%3ADescription%3E%0D%0A+++++%3Cogc%3AFilter+xmlns%3Aogc%3D%22http%3A%2F%2Fwww.opengis.net%2Fogc%22%3E%0D%0A++++++%3Cogc%3APropertyIsEqualTo%3E%0D%0A+++++++%3Cogc%3APropertyName%3Etyp_code%3C%2Fogc%3APropertyName%3E%0D%0A+++++++%3Cogc%3ALiteral%3ES1%3C%2Fogc%3ALiteral%3E%0D%0A++++++%3C%2Fogc%3APropertyIsEqualTo%3E%0D%0A+++++%3C%2Fogc%3AFilter%3E%0D%0A+++++%3Cse%3APolygonSymbolizer%3E%0D%0A++++++%3Cse%3AFill%3E%0D%0A+++++++%3Cse%3ASvgParameter+name%3D%22fill%22%3E%23003bb3%3C%2Fse%3ASvgParameter%3E%0D%0A++++++%3C%2Fse%3AFill%3E%0D%0A++++++%3Cse%3AStroke%3E%0D%0A+++++++%3Cse%3ASvgParameter+name%3D%22stroke%22%3E%23000080%3C%2Fse%3ASvgParameter%3E%0D%0A+++++++%3Cse%3ASvgParameter+name%3D%22stroke-width%22%3E1%3C%2Fse%3ASvgParameter%3E%0D%0A+++++++%3Cse%3ASvgParameter+name%3D%22stroke-linejoin%22%3Ebevel%3C%2Fse%3ASvgParameter%3E%0D%0A++++++%3C%2Fse%3AStroke%3E%0D%0A+++++%3C%2Fse%3APolygonSymbolizer%3E%0D%0A++++%3C%2Fse%3ARule%3E%0D%0A+++%3C%2Fse%3AFeatureTypeStyle%3E%0D%0A++%3C%2FUserStyle%3E%0D%0A+%3C%2FNamedLayer%3E%0D%0A%3C%2FStyledLayerDescriptor%3E
>
> The response is:
>
> <ServiceExceptionReport xmlns="http://www.opengis.net/ogc" version="1.3.0">
> <ServiceException code="Invalid Parameter">
> SLD ('<StyledLayerDescriptor xmlns="http://www.opengis.net/sld"
> xmlns:xlink="http://www.w3.org/1999/xlink"
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:schemaLocation="http://www.opengis.net/sld
> http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd"
> xmlns:se="http://www.opengis.net/se" version="1.1.0"
> xmlns:ogc="http://www.opengis.net/ogc"> <NamedLayer>
> <se:Name>ch.zg.grundwasserschutz.gwszonen</se:Name> <UserStyle>
> <se:Name>default</se:Name> <se:FeatureTypeStyle> <se:Rule>
> <se:Name>Grundwasserschutzzone S1</se:Name> <se:Description>
> <se:Title>Grundwasserschutzzone S1</se:Title> </se:Description>
> <ogc:Filter xmlns:ogc="http://www.opengis.net/ogc">
> <ogc:PropertyIsEqualTo> <ogc:PropertyName>typ_code</ogc:PropertyName>
> <ogc:Literal>S1</ogc:Literal> </ogc:PropertyIsEqualTo> </ogc:Filter>
> <se:PolygonSymbolizer> <se:Fill> <se:SvgParameter
> name="fill">#003bb3</se:SvgParameter> </se:Fill> <se:Stroke>
> <se:SvgParameter name="stroke">#000080</se:SvgParameter>
> <se:SvgParameter name="stroke-width">1</se:SvgParameter>
> <se:SvgParameter name="stroke-linejoin">bevel</se:SvgParameter>
> </se:Stroke> </se:PolygonSymbolizer> </se:Rule> </se:FeatureTypeStyle>
> </UserStyle> </NamedLayer> </StyledLayerDescriptor>') cannot be
> converted into QString
> </ServiceException>
> </ServiceExceptionReport>
>  
> So apparently the SLD cannot be converted to a QString. Is my encoding
> in the URL above wrong or am I missing a required additional parameter?
>  
> Can you point me to an example how to create a valid GetMap request
> with an SLD submitted?
>  
> Thanks a lot,
> Andreas
>
> On 2019-04-09 15:38, Andreas Neumann wrote:
>
>> Hi,
>>
>> Does QGIS-Server support SLD styles to filter away RULEs in a GetMap
>> Request?
>>
>> I would assume, yes, but in what encoding would I submit such an SLD
>> in a GET request? I know that one should rather use POST reqests for
>> such long parameters, but for experimenting, it would be ok to use GET.
>>
>> The idea would be to allow users to enable/disable categories within
>> a given layer.
>>
>> The WMS client would first request the available rules with a
>> GetStyles command (that part works fine) and would then filter the
>> RULE (strip away the unwanted RULEs) and resubmit the GetMap with an
>> SLD. Does that work with QGIS server?
>>
>> I know that one can also use the FILTER parameter, but we want to do
>> it in an OGC compatible way, since the client being developed should
>> work with any OGC compatible WMS server.
>>
>> Thanks for your reply,
>>
>> Andreas
>>
>>
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>
>
>
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