[mapserver-users] Geojson output from WFS is missing ID

[Rahkonen Jukka (MML)]

About the format of GetFeatureByID, I can actually read the standard myself.

"11.3.5
GetFeatureById response
Executing a GetFeature operation containing the GetFeatureById stored query (see 7.9.3.6) shall generate a response composed of a single feature encoded according to the values of the outputFormat parameter (see 7.6.3.7). The response shall only contain the feature XML without any of the normal containing elements generated as a result of executing a GetFeature operation (see 11.3.3.4, 11.3.3.5, 11.3.3.6)."

So it must be a feature and wrapping it into FeatureCollection is not accepted.

-Jukka-


-----Alkuperäinen viesti-----
Lähettäjä: Rahkonen Jukka (MML) 
Lähetetty: 10. toukokuuta 2016 14:08
Vastaanottaja: mapserver-users at lists.osgeo.org
Aihe: Re: VS: [mapserver-users] Geojson output from WFS is missing ID

Hi,

Geoserver breaking GML 3.2.1 schema is even documented in http://docs.geoserver.org/2.8.3/user/data/app-schema/supported-gml-versions.html, section GML 3.2.1 geometries require gml:id, including an application schema example about how to make it GML 3.2.1 compliant.

So Mapserver WFS 2.0 does not return a FeatureCollection with members with GetFeatureByID but only a feature. The gml:id "states.1" is in the very beginning of the GML and it is the gml:id of the feature. In the geometry there is gml:id "states.1.1" and it means roughly "first geometry of the feature states.1". 
However, with GeoJSON as an outputformat the geometry is wrapped into a FeatureCollection probably because GeoJSON required it to be so. But would it be wrong to wrap also the GML 3.2.1 output of GetFeatureByID into a FeatureCollection?

-Jukka-

-----Alkuperäinen viesti-----
Even Rouault wrote:

Le mardi 10 mai 2016 12:32:17, Rahkonen Jukka (MML) a écrit :
> Hi,
> 
> Do you mean that the output from GeoServer WFS 2.0 is not valid 
> because it does not seem to have gml:id for the collection, nor for 
> the geometries, but it does have gml:id for the members?
> 
> <wfs:FeatureCollection numberMatched="49" numberReturned="49"
> timeStamp="2016-05-10T10:23:29.813Z"
> xsi:schemaLocation="http://www.opengis.net/wfs/2.0
> http://localhost:8080/geoserver/schemas/wfs/2.0/wfs.xsd
> http://www.openplans.org/topp
> http://localhost:8080/geoserver/wfs?service=WFS&version=2.0.0&request=
> Desc ribeFeatureType&typeName=topp%3Astates
> http://www.opengis.net/gml/3.2
> http://localhost:8080/geoserver/schemas/gml/3.2.1/gml.xsd"><wfs:member
> ><to pp:states gml:id="states.1"><topp:the_geom><gml:MultiSurface
> srsName="urn:ogc:def:crs:EPSG::4326"
> srsDimension="2"><gml:surfaceMember><gml:Polygon><gml:exterior><gml:Li
> near
> Ring><gml:posList>

Yes, this will not validate the gml 3.2.1 schema. See for example http://www.datypic.com/sc/niem21/e-gml32_MultiSurface.html
gml:id being compulsory on geometries is one of the main difference between gml
3.2 and 3.1

> 
> -Jukka Rahkonen-
> 
> Even Rouault wrote:
> > Le mardi 10 mai 2016 12:08:07, Rahkonen Jukka (MML) a écrit :
> >> Hi,
> >> 
> >> WFS output from Mapserver 7.0 in GML contain gml:id 
> >> <ms:msGeometry><gml:Polygon gml:id="states.1"
> >> srsName="urn:ogc:def:crs:EPSG::4326">
> > 
> > It looks like you must use WFS 2.0 and/or GML 3.2 output. In that 
> > case the GML
> 
> 3.2 schemas require each geometry to have a gml:id. So this is a 
> geometry id, not a feature id ( in case of geometry collections, 
> you'll have one id for the collection and as many ids as members) To 
> address that technical requirement, MapServer generates it in a 
> sequential way for the output of each request. Not completely sure it 
> matches the uniqueness intended but at least it validates schemas. So 
> this particular one is not a good candidate to be exported to other 
> formats, but I see Thomas has just replied for the feature id.
> 
> >> However, with GeoJSON as outputformat the id is missing:
> >> {
> >> "type": "FeatureCollection",
> >> "crs": { "type": "name", "properties": { "name":
> >> "urn:ogc:def:crs:OGC:1.3:CRS84" } }, "features": [ { "type":
> >> "Feature", "properties": { "PK_UID": 1, "STATE_NAME": "Illinois",
> >> 
> >> 
> >> GeoJSON specification says in
> >> http://geojson.org/geojson-spec.html#feature-objects: "If a feature 
> >> has a commonly used identifier, that identifier should be included 
> >> as a member of the feature object with the name "id"."
> >> 
> >> GeoJSON from Geoserver WFS does contain the id:
> >> 
> >> {"type":"FeatureCollection","totalFeatures":49,"features":[{"type":
> >> "Fe ature ","id":"states.1","geometry":{"type":"MultiPolygon"
> >> 
> >> Should this be classified as a bug or a candidate for a featere request?
> >> 
> >> -Jukka Rahkonen-
> 
> --
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