#138 WIP Validity

* adds geometry validity checks for SimpleGeomForm is_valid()
    * shows validity problems on the form if a feature is invalid
* optimizes merging of different features into one MultiPolygon
* further enhances tests
* adds as_feature_collection() method on Geometry model for converting geom MultiPolygon attribute into FeatureCollection json holding each polygon as an own feature -> makes each polygon selectable in new netgis map client

compensation/tests/compensation/test_workflow.py

@@ -128,6 +128,7 @@ class CompensationWorkflowTestCase(BaseWorkflowTestCase):
         new_identifier = self.create_dummy_string()
         new_comment = self.create_dummy_string()
         new_geometry = MultiPolygon(srid=4326)  # Create an empty geometry
+        geojson = self.create_geojson(new_geometry)
 
         check_on_elements = {
             self.compensation.title: new_title,
@@ -142,7 +143,7 @@ class CompensationWorkflowTestCase(BaseWorkflowTestCase):
             "title": new_title,
             "intervention": self.intervention.id,  # just keep the intervention as it is
             "comment": new_comment,
-            "geom": new_geometry.geojson,
+            "geom": geojson,
         }
         self.client_user.post(url, post_data)
         self.compensation.refresh_from_db()

konova/forms.py

@@ -17,8 +17,8 @@ from django.db.models.fields.files import FieldFile
 
 from konova.sub_settings.lanis_settings import DEFAULT_SRID_RLP
 from user.models import User
-from django.contrib.gis.forms import OSMWidget, MultiPolygonField
-from django.contrib.gis.geos import MultiPolygon, GEOSGeometry, Polygon
+from django.contrib.gis.forms import MultiPolygonField
+from django.contrib.gis.geos import MultiPolygon, Polygon
 from django.db import transaction
 from django.http import HttpRequest, HttpResponseRedirect
 from django.shortcuts import render
@@ -291,11 +291,13 @@ class SimpleGeomForm(BaseForm):
         # Initialize geometry
         try:
             geom = self.instance.geometry.geom
-            geom.transform(ct=DEFAULT_SRID_RLP)
             self.empty = geom.empty
+
             if self.empty:
                 raise AttributeError
-            geom = geom.geojson
+
+            geojson = self.instance.geometry.as_feature_collection(srid=DEFAULT_SRID_RLP)
+            geom = json.dumps(geojson)
         except AttributeError:
             # If no geometry exists for this form, we simply set the value to None and zoom to the maximum level
             geom = ""
@@ -326,19 +328,26 @@ class SimpleGeomForm(BaseForm):
                 self.add_error("geom", _("Only surfaces allowed. Points or lines must be buffered."))
                 is_valid = False
                 return is_valid
-            features.append(g)
-        if len(features) > 0:
-            form_geom = features[0]
-            for g in features[1:]:
-                form_geom = form_geom.union(g)
-            form_geom.transform(coord_trans=DEFAULT_SRID)
+
+            polygon = Polygon.from_ewkt(g.ewkt)
+            is_valid = polygon.valid
+            if not is_valid:
+                self.add_error("geom", polygon.valid_reason)
+                return is_valid
+
+            features.append(polygon)
+        form_geom = MultiPolygon(srid=DEFAULT_SRID_RLP)
+        for feature in features:
+            form_geom = form_geom.union(feature)
+
+        # Make sure to convert into a MultiPolygon. Relevant if a single Polygon is provided.
         if form_geom.geom_type != "MultiPolygon":
-                form_geom = MultiPolygon(MultiPolygon.from_ewkt(form_geom.ewkt))
+            form_geom = MultiPolygon(form_geom, srid=DEFAULT_SRID_RLP)
 
         # Write unioned Multipolygon into cleaned data
         if self.cleaned_data is None:
             self.cleaned_data = {}
-            self.cleaned_data["geom"] = form_geom.wkt
+        self.cleaned_data["geom"] = form_geom.ewkt
 
         return is_valid
 

konova/models/geometry.py

@@ -5,11 +5,15 @@ Contact: michel.peltriaux@sgdnord.rlp.de
 Created on: 15.11.21
 
 """
+import json
+
 from django.contrib.gis.db.models import MultiPolygonField
+from django.contrib.gis.geos import Polygon
 from django.db import models, transaction
 from django.utils import timezone
 
 from konova.models import BaseResource, UuidModel
+from konova.sub_settings.lanis_settings import DEFAULT_SRID_RLP
 from konova.utils.wfs.spatial import ParcelWFSFetcher
 
 
@@ -179,6 +183,34 @@ class Geometry(BaseResource):
 
         return parcels
 
+    def as_feature_collection(self, srid=DEFAULT_SRID_RLP):
+        """ Returns a FeatureCollection structure holding all polygons of the MultiPolygon as single features
+
+        This method is used to convert a single MultiPolygon into multiple Polygons, which can be used as separated
+        features in the NETGIS map client.
+
+        Args:
+            srid (int): The spatial reference system identifier to be transformed to
+
+        Returns:
+            geojson (dict): The FeatureCollection json (as dict)
+        """
+        geom = self.geom
+        geom.transform(ct=srid)
+
+        polygons = []
+        for coords in geom.coords:
+            p = Polygon(coords[0], srid=geom.srid)
+            polygons.append(p)
+        geojson = {
+            "type": "FeatureCollection",
+            "features": [
+                json.loads(x.geojson) for x in polygons
+            ]
+        }
+        return geojson
+
+
 
 class GeometryConflict(UuidModel):
     """

konova/tests/test_views.py

@@ -432,11 +432,12 @@ class BaseTestCase(TestCase):
             return
 
         if geom1.srid != geom2.srid:
+            tolerance = 0.001
             # Due to prior possible transformation of any of these geometries, we need to make sure there exists a
             # transformation from one coordinate system into the other, which is valid
             geom1_t = geom1.transform(geom2.srid, clone=True)
             geom2_t = geom2.transform(geom1.srid, clone=True)
-            self.assertTrue(geom1_t.equals(geom2) or geom2_t.equals(geom1))
+            self.assertTrue(geom1_t.equals_exact(geom2, tolerance) or geom2_t.equals_exact(geom1, tolerance))
         else:
             self.assertTrue(geom1.equals(geom2))