Hi,

The vendor specific filters are listed in the WFS  GetCapabilities. Try 
https://demo.geo-solutions.it/geoserver/wfs?service=WFS&version=2.0.0&request=GetCapabilities
 and you will find a lot of filters, including “Nearest”. I do not know the 
exact syntax to use in WFS filter but perhaps Andrea is lurking this list and 
can show some light for us.

The function list is per WFS service and that may be problematic with filters 
like pgnearest and SDO_NN which can work only with PostGIS and Oracle layers, 
respectively.

-Jukka Rahkonen-

Lähettäjä: Steve Lime <sdl...@gmail.com>
Lähetetty: maanantai 27. huhtikuuta 2020 21.42
Vastaanottaja: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi>
Kopio: Fran Acuña Parra <fran.a...@gmail.com>; mapserver-users@lists.osgeo.org
Aihe: Re: [mapserver-users] GetFeature WFS request with Spatial Filter DWITHIN

To be clear, Fran - are you saying the issue isn't the result set rather the 
order? If so I don't know of a way to affect that order.

In terms of a nearest feature or features. This would be something that I would 
be keen on addressing. I've run into a variant of this issue using the CGI and 
mode=query when searching multiple layers. The query finds the first matching 
feature but not necessarily the closest. It's an issue primarily with line and 
point layers when you need to set TOLERANCE values to make things clickable. 
Jukka, what does the vendor specific extension in GeoServer look like from WFS 
filter standpoint?

--Steve

On Mon, Apr 27, 2020 at 10:21 AM Rahkonen Jukka (MML) 
<jukka.rahko...@maanmittauslaitos.fi<mailto:jukka.rahko...@maanmittauslaitos.fi>>
 wrote:
Hi,

The DWithin function in WFS is a true/false function just like the equivalent 
PostGIS function https://postgis.net/docs/ST_DWithin.html. You can’t find the 
nearest feature with DWithin. A not so good workaround is to increase the 
distance until the result is not empty.

Mapserver does not have a vendor specific function for nearest either like 
Geotools/Geoserver. Especially the pgnearest function that works with PostGIS 
backend and returns n nearest features would be practical for your use case  
https://docs.geotools.org/stable/userguide/library/main/function_list.html.  
Geotools should also have a similar function for Oracle that is using the 
native SDO_NN function.

Unfortunately I can’t say how to proceed for making nearest or nearestN queries 
with Mapserver.

-Jukka Rahkonen-

Lähettäjä: mapserver-users 
<mapserver-users-boun...@lists.osgeo.org<mailto:mapserver-users-boun...@lists.osgeo.org>>
 Puolesta Fran Acuña Parra
Lähetetty: maanantai 27. huhtikuuta 2020 16.59
Vastaanottaja: 
mapserver-users@lists.osgeo.org<mailto:mapserver-users@lists.osgeo.org>
Aihe: [mapserver-users] GetFeature WFS request with Spatial Filter DWITHIN

Hi,

Following the topic about another question that I sent, I'm using a Getfeature 
WFS request with a DWITHIN spatial filter to returns the closes feature of a 
layer given some specific coordinates. The request works fine, but when there 
are several features that match the filter it doesn't returns the closest one 
in the first position of the response(GML for example). Is there a way to 
achieve this?

Thanks in advance.

Regards,

Fran Acuña
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