[postgis-devel] [PostGIS] #1377: GML for empty geometries should be NULL

[PostGIS]

#1377: GML for empty geometries should be NULL
---------------------+------------------------------------------------------
 Reporter:  strk     |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 2.0.0
Component:  postgis  |     Version:  trunk        
 Keywords:           |  
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Comment(by aperi2007):

 Hi,
 I tested with xml-spy the available solutions so this solutions are all
 acceptable with the xsd rules of GML 3.1.1


 {{{
         <gml:MultiCurve srsName="urn:ogc:def:crs:EPSG:3003">
           <gml:curveMember>
             <gml:Curve>
               <gml:segments>
                 <gml:LineStringSegment>
                   <gml:posList srsDimension="2"></gml:posList>
                 </gml:LineStringSegment>
               </gml:segments>
             </gml:Curve>
           </gml:curveMember>
         </gml:MultiCurve>

         <gml:MultiCurve srsName="urn:ogc:def:crs:EPSG:3003">
           <gml:curveMember>
             <gml:Curve>
               <gml:segments>
                 <gml:LineStringSegment>
                   <gml:posList srsDimension="2" />
                 </gml:LineStringSegment>
               </gml:segments>
             </gml:Curve>
           </gml:curveMember>
         </gml:MultiCurve>

 <gml:LineString srsName="urn:ogc:def:crs:EPSG:3003">
    <gml:posList srsDimension="2" />
 </gml:LineString>

 <gml:Point srsName="urn:ogc:def:crs:EPSG:3003">
   <gml:pos srsDimension="2" />
 </gml:Point>

 <gml:MultiPoint srsName="urn:ogc:def:crs:EPSG:3003">
   <gml:pointMember>
     <gml:Point>
       <gml:pos srsDimension="2" />
     </gml:Point>
   </gml:pointMember>
 </gml:MultiPoint>

 <gml:TopoCurve>
   <gml:directedEdge>
     <gml:Edge gml:id="Edge_32_2174" >
       <gml:directedNode orientation="-">
         <gml:Node gml:id="Node_1_231068"/>
       </gml:directedNode>
       <gml:directedNode xlink:href="#Node_1_231068"/>
       <gml:curveProperty>
         <gml:LineString srsName="urn:ogc:def:crs:EPSG:3003">
           <gml:posList srsDimension="2" />
         </gml:LineString>
       </gml:curveProperty>
     </gml:Edge>
   </gml:directedEdge>
 </gml:TopoCurve>



 }}}

 please notice that this instead give an error to validate test:


 {{{
 <gml:TopoCurve>
   <gml:directedEdge>
     <gml:Edge gml:id="Edge_32_2174">
       <gml:directedNode orientation="-">
         <gml:Node gml:id="Node_1_231068"/>
       </gml:directedNode>
       <gml:directedNode xlink:href="#Node_1_231068"/>
       <gml:curveProperty>
         <gml:LineString srsName="urn:ogc:def:crs:EPSG:3003"/>
       </gml:curveProperty>
     </gml:Edge>
   </gml:directedEdge>
 </gml:TopoCurve>

 also this is not allowed:

 <gml:TopoCurve>
   <gml:directedEdge>
     <gml:Edge gml:id="Edge_32_2174" />
   </gml:directedEdge>
 </gml:TopoCurve>

 }}}

 instead this is compliant with xsd validate:

 {{{
 <gml:TopoCurve>
   <gml:directedEdge>
     <gml:Edge gml:id="Edge_32_2174">
       <gml:directedNode orientation="-">
         <gml:Node gml:id="Node_1_231068"/>
       </gml:directedNode>
       <gml:directedNode xlink:href="#Node_1_231068"/>
       <gml:curveProperty />
     </gml:Edge>
   </gml:directedEdge>
 </gml:TopoCurve>

 }}}

 So I Guess the better strategy is put always on the posList or pos tag the
 null,
 using

 <posList />
 or
 <pos />

 regards,

 Andrea.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/1377#comment:1>
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