#160 Parcel calc fix

* fixes minor bug where invalid geometry (self intersecting) could not be used properly as input for WFS parcel intersection calculation
    * future enhancements regarding map client will make sure invalid geometries can not be added in the first place

konova/utils/wfs/spatial.py

@@ -11,7 +11,7 @@ from json import JSONDecodeError
 from time import sleep
 
 import requests
-from django.contrib.gis.db.models.functions import AsGML, Transform
+from django.contrib.gis.db.models.functions import AsGML, Transform, MakeValid
 from requests.auth import HTTPDigestAuth
 
 from konova.settings import DEFAULT_SRID_RLP, PARCEL_WFS_USER, PARCEL_WFS_PW, PROXIES
@@ -91,7 +91,7 @@ class ParcelWFSFetcher(AbstractWFSFetcher):
         ).annotate(
             transformed=Transform(srid=filter_srid, expression="geom")
         ).annotate(
-            gml=AsGML('transformed')
+            gml=AsGML(MakeValid('transformed'))
         ).first().gml
         spatial_filter = f"<Filter><{geometry_operation}><PropertyName>{self.geometry_property_name}</PropertyName>{geom_gml}</{geometry_operation}></Filter>"
         return spatial_filter