compensation/tables.py

@@ -133,7 +133,9 @@ class CompensationTable(BaseTable, TableRenderMixin):
         Returns:
 
         """
-        parcels = value.parcels.values_list(
+        parcels = value.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).values_list(
             "gmrkng",
             flat=True
         ).distinct()
@@ -294,7 +296,9 @@ class EcoAccountTable(BaseTable, TableRenderMixin):
         Returns:
 
         """
-        parcels = value.parcels.values_list(
+        parcels = value.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).values_list(
             "gmrkng",
             flat=True
         ).distinct()

ema/tables.py

@@ -103,7 +103,9 @@ class EmaTable(BaseTable, TableRenderMixin):
         Returns:
 
         """
-        parcels = value.parcels.values_list(
+        parcels = value.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).values_list(
             "gmrkng",
             flat=True
         ).distinct()

intervention/tables.py

@@ -130,7 +130,9 @@ class InterventionTable(BaseTable, TableRenderMixin):
         Returns:
 
         """
-        parcels = value.parcels.values_list(
+        parcels = value.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).values_list(
             "gmrkng",
             flat=True
         ).distinct()

konova/migrations/0003_auto_20220208_1801.py

@@ -0,0 +1,54 @@
+# Generated by Django 3.1.3 on 2022-02-08 17:01
+
+from django.db import migrations, models
+import django.db.models.deletion
+import uuid
+
+
+def migrate_parcels(apps, schema_editor):
+    Geometry = apps.get_model('konova', 'Geometry')
+    SpatialIntersection = apps.get_model('konova', 'SpatialIntersection')
+
+    all_geoms = Geometry.objects.all()
+    for geom in all_geoms:
+        SpatialIntersection.objects.bulk_create([
+            SpatialIntersection(geometry=geom, parcel=parcel)
+            for parcel in geom.parcels.all()
+        ])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('konova', '0002_auto_20220114_0936'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='SpatialIntersection',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('calculated_on', models.DateTimeField(auto_now_add=True, null=True)),
+                ('geometry', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='konova.geometry')),
+                ('parcel', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='konova.parcel')),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+        migrations.RunPython(migrate_parcels),
+        migrations.AddField(
+            model_name='parcel',
+            name='geometries_tmp',
+            field=models.ManyToManyField(blank=True, related_name='parcels', through='konova.SpatialIntersection', to='konova.Geometry'),
+        ),
+        migrations.RemoveField(
+            model_name='parcel',
+            name='geometries',
+        ),
+        migrations.RenameField(
+            model_name='parcel',
+            old_name='geometries_tmp',
+            new_name='geometries',
+        ),
+    ]

konova/migrations/0004_auto_20220209_0839.py

@@ -0,0 +1,17 @@
+# Generated by Django 3.1.3 on 2022-02-09 07:39
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('konova', '0003_auto_20220208_1801'),
+    ]
+
+    operations = [
+        migrations.RenameModel(
+            old_name='SpatialIntersection',
+            new_name='ParcelIntersection',
+        ),
+    ]

konova/models/geometry.py

@@ -99,7 +99,7 @@ class Geometry(BaseResource):
         Returns:
 
         """
-        from konova.models import Parcel, District
+        from konova.models import Parcel, District, ParcelIntersection
         parcel_fetcher = ParcelWFSFetcher(
             geometry_id=self.id,
         )
@@ -107,6 +107,7 @@ class Geometry(BaseResource):
         fetched_parcels = parcel_fetcher.get_features(
             typename
         )
+        _now = timezone.now()
         underlying_parcels = []
         for result in fetched_parcels:
             fetched_parcel = result[typename]
@@ -125,19 +126,35 @@ class Geometry(BaseResource):
                 krs=fetched_parcel["ave:kreis"],
             )[0]
             parcel_obj.district = district
-            parcel_obj.updated_on = timezone.now()
+            parcel_obj.updated_on = _now
             parcel_obj.save()
             underlying_parcels.append(parcel_obj)
 
+        # Update the linked parcels
         self.parcels.set(underlying_parcels)
 
+        # Set the calculated_on intermediate field, so this related data will be found on lookups
+        intersections_without_ts = self.parcelintersection_set.filter(
+            parcel__in=self.parcels.all(),
+            calculated_on__isnull=True,
+        )
+        for entry in intersections_without_ts:
+            entry.calculated_on = _now
+        ParcelIntersection.objects.bulk_update(
+            intersections_without_ts,
+            ["calculated_on"]
+        )
+
     def get_underlying_parcels(self):
         """ Getter for related parcels and their districts
 
         Returns:
             parcels (QuerySet): The related parcels as queryset
         """
-        parcels = self.parcels.all().prefetch_related(
+
+        parcels = self.parcels.filter(
+            parcelintersection__calculated_on__isnull=False,
+        ).prefetch_related(
             "district"
         ).order_by(
             "gmrkng",

konova/models/parcel.py

@@ -22,7 +22,7 @@ class Parcel(UuidModel):
     To avoid conflicts due to german Umlaute, the field names are shortened and vocals are dropped.
 
     """
-    geometries = models.ManyToManyField("konova.Geometry", related_name="parcels", blank=True)
+    geometries = models.ManyToManyField("konova.Geometry", blank=True, related_name="parcels", through='ParcelIntersection')
     district = models.ForeignKey("konova.District", on_delete=models.SET_NULL, null=True, blank=True, related_name="parcels")
     gmrkng = models.CharField(
         max_length=1000,
@@ -77,3 +77,22 @@ class District(UuidModel):
 
     def __str__(self):
         return f"{self.gmnd} | {self.krs}"
+
+
+class ParcelIntersection(UuidModel):
+    """ ParcelIntersection is an intermediary model, which is used to configure the
+    M2M relation between Parcel and Geometry.
+
+    Based on uuids, we will not have (practically) any problems on outrunning primary keys
+    and extending the model with calculated_on timestamp, we can 'hide' entries while they
+    are being recalculated and keep track on the last time they have been calculated this
+    way.
+
+    Please note: The calculated_on describes when the relation between the Parcel and the Geometry
+    has been established. The updated_on field of Parcel describes when this Parcel has been
+    changed the last time.
+
+    """
+    parcel = models.ForeignKey(Parcel, on_delete=models.CASCADE)
+    geometry = models.ForeignKey("konova.Geometry", on_delete=models.CASCADE)
+    calculated_on = models.DateTimeField(auto_now_add=True, null=True, blank=True)

konova/tasks.py

@@ -4,13 +4,19 @@ from celery import shared_task
 from django.core.exceptions import ObjectDoesNotExist
 
 
-
 @shared_task
 def celery_update_parcels(geometry_id: str, recheck: bool = True):
-    from konova.models import Geometry
+    from konova.models import Geometry, ParcelIntersection
     try:
         geom = Geometry.objects.get(id=geometry_id)
-        geom.parcels.clear()
+        objs = geom.parcelintersection_set.all()
+        for obj in objs:
+            obj.calculated_on = None
+        ParcelIntersection.objects.bulk_update(
+            objs,
+            ["calculated_on"]
+        )
+
         geom.update_parcels()
     except ObjectDoesNotExist:
         if recheck: