# Issue #381

* adds another validity check to SimpleGeomForm (is_size_valid) to make sure the area of the entered geometry is somehow rational (>= 1m²)
* optimizes performance of django command sanitize_db
* extends Geometry model with two new attributes, holding timestamps when a parcel calculation has been started and ended
* finally drops unused update_parcel_wfs in favor of update_parcels in Geometry model
* refactors update_parcel method
* adds geometry buffer fallback in schneider/fetcher.py to avoid emptying of geometries when parcels shall be fetched
* finally removes utils/wfs/spatial.py
* extends GeomParcelsView according to #381
* updates translations
* removes redundant psycopg2-binary requirement

konova/forms/geometry_form.py

@@ -98,12 +98,14 @@ class SimpleGeomForm(BaseForm):
 
             if g.geom_type not in accepted_ogr_types:
                 self.add_error("geom", _("Only surfaces allowed. Points or lines must be buffered."))
-                is_valid = False
+                is_valid &= False
                 return is_valid
 
+            is_valid &= self.__is_size_valid(g)
+
             polygon = Polygon.from_ewkt(g.ewkt)
-            is_valid = polygon.valid
+            is_valid &= polygon.valid
-            if not is_valid:
+            if not polygon.valid:
                 self.add_error("geom", polygon.valid_reason)
                 return is_valid
 
@@ -137,6 +139,24 @@ class SimpleGeomForm(BaseForm):
 
         return num_vertices <= GEOM_MAX_VERTICES
 
+    def __is_size_valid(self, geom: gdal.OGRGeometry):
+        """ Checks whether the number of vertices in the geometry is not too high
+
+        Returns:
+
+        """
+        is_area_valid = geom.area > 1  # > 1m² (SRID:25832)
+
+        if not is_area_valid:
+            self.add_error(
+                "geom",
+                _("Geometry must be greater than 1m². Currently is {}m²").format(
+                    float(geom.area)
+                )
+            )
+
+        return is_area_valid
+
     def __simplify_geometry(self, geom, max_vert: int):
         """ Simplifies a geometry
 

konova/management/commands/sanitize_db.py

@@ -61,14 +61,24 @@ class Command(BaseKonovaCommand):
             action=UserAction.CREATED
         )
 
-        intervention_log_entries_ids = self.get_all_log_entries_ids(Intervention)
+        EIV_log_entries_ids = self.get_all_log_entries_ids(Intervention)
-        attached_log_entries_id = intervention_log_entries_ids.union(
+        self._write_warning(f"   EIV: {EIV_log_entries_ids.count()} attached log entries")
-            self.get_all_log_entries_ids(Compensation),
+        KOM_log_entries_ids = self.get_all_log_entries_ids(Compensation)
-            self.get_all_log_entries_ids(EcoAccount),
+        self._write_warning(f"   KOM: {KOM_log_entries_ids.count()} attached log entries")
-            self.get_all_log_entries_ids(Ema),
+        OEK_log_entries_ids = self.get_all_log_entries_ids(EcoAccount)
-        )
+        self._write_warning(f"   OEK: {OEK_log_entries_ids.count()} attached log entries")
+        EMA_log_entries_ids = self.get_all_log_entries_ids(Ema)
+        self._write_warning(f"   EMA: {EMA_log_entries_ids.count()} attached log entries")
 
-        unattached_log_entries = all_log_entries.exclude(id__in=attached_log_entries_id)
+        unattached_log_entries = all_log_entries.exclude(
+            id__in=EIV_log_entries_ids
+        ).exclude(
+            id__in=KOM_log_entries_ids
+        ).exclude(
+            id__in=OEK_log_entries_ids
+        ).exclude(
+            id__in=EMA_log_entries_ids
+        )
 
         num_entries = unattached_log_entries.count()
         if num_entries > 0:
@@ -108,13 +118,20 @@ class Command(BaseKonovaCommand):
         self._write_warning("=== Sanitize compensation actions ===")
         all_actions = CompensationAction.objects.all()
 
-        compensation_action_ids = self.get_all_action_ids(Compensation)
+        kom_action_ids = self.get_all_action_ids(Compensation)
-        attached_action_ids = compensation_action_ids.union(
+        self._write_warning(f"   KOM: {kom_action_ids.count()} attached actions")
-            self.get_all_action_ids(EcoAccount),
+        oek_action_ids = self.get_all_action_ids(EcoAccount)
-            self.get_all_action_ids(Ema),
+        self._write_warning(f"   OEK: {oek_action_ids.count()} attached actions")
-        )
+        ema_action_ids = self.get_all_action_ids(Ema)
+        self._write_warning(f"   EMA: {ema_action_ids.count()} attached actions")
 
-        unattached_actions = all_actions.exclude(id__in=attached_action_ids)
+        unattached_actions = all_actions.exclude(
+            id__in=kom_action_ids
+        ).exclude(
+            id__in=oek_action_ids
+        ).exclude(
+            id__in=ema_action_ids
+        )
 
         num_entries = unattached_actions.count()
         if num_entries > 0:
@@ -125,7 +142,7 @@ class Command(BaseKonovaCommand):
             self._write_success("No unattached actions found.")
         self._break_line()
 
-    def get_all_deadline_ids(self, cls):
+    def _get_all_deadline_ids(self, cls):
         """ Getter for all deadline ids of a model
 
         Args:
@@ -154,13 +171,20 @@ class Command(BaseKonovaCommand):
         self._write_warning("=== Sanitize deadlines ===")
         all_deadlines = Deadline.objects.all()
 
-        compensation_deadline_ids = self.get_all_deadline_ids(Compensation)
+        kom_deadline_ids = self._get_all_deadline_ids(Compensation)
-        attached_deadline_ids = compensation_deadline_ids.union(
+        self._write_warning(f"   KOM: {kom_deadline_ids.count()} attached deadlines")
-            self.get_all_deadline_ids(EcoAccount),
+        oek_deadline_ids = self._get_all_deadline_ids(EcoAccount)
-            self.get_all_deadline_ids(Ema),
+        self._write_warning(f"   OEK: {kom_deadline_ids.count()} attached deadlines")
-        )
+        ema_deadline_ids = self._get_all_deadline_ids(Ema)
+        self._write_warning(f"   EMA: {kom_deadline_ids.count()} attached deadlines")
 
-        unattached_deadlines = all_deadlines.exclude(id__in=attached_deadline_ids)
+        unattached_deadlines = all_deadlines.exclude(
+            id__in=kom_deadline_ids
+        ).exclude(
+            id__in=oek_deadline_ids
+        ).exclude(
+            id__in=ema_deadline_ids
+        )
 
         num_entries = unattached_deadlines.count()
         if num_entries > 0:
@@ -171,7 +195,7 @@ class Command(BaseKonovaCommand):
             self._write_success("No unattached deadlines found.")
         self._break_line()
 
-    def get_all_geometry_ids(self, cls):
+    def _get_all_geometry_ids(self, cls):
         """ Getter for all geometry ids of a model
 
         Args:
@@ -200,14 +224,24 @@ class Command(BaseKonovaCommand):
         self._write_warning("=== Sanitize geometries ===")
         all_geometries = Geometry.objects.all()
 
-        compensation_geometry_ids = self.get_all_geometry_ids(Compensation)
+        kom_geometry_ids = self._get_all_geometry_ids(Compensation)
-        attached_geometry_ids = compensation_geometry_ids.union(
+        self._write_warning(f"   EMA: {kom_geometry_ids.count()} attached geometries")
-            self.get_all_geometry_ids(Intervention),
+        eiv_geometry_ids = self._get_all_geometry_ids(Intervention)
-            self.get_all_geometry_ids(EcoAccount),
+        self._write_warning(f"   EMA: {eiv_geometry_ids.count()} attached geometries")
-            self.get_all_geometry_ids(Ema),
+        oek_geometry_ids = self._get_all_geometry_ids(EcoAccount)
-        )
+        self._write_warning(f"   EMA: {oek_geometry_ids.count()} attached geometries")
+        ema_geometry_ids = self._get_all_geometry_ids(Ema)
+        self._write_warning(f"   EMA: {ema_geometry_ids.count()} attached geometries")
 
-        unattached_geometries = all_geometries.exclude(id__in=attached_geometry_ids)
+        unattached_geometries = all_geometries.exclude(
+            id__in=kom_geometry_ids
+        ).exclude(
+            id__in=eiv_geometry_ids
+        ).exclude(
+            id__in=oek_geometry_ids
+        ).exclude(
+            id__in=ema_geometry_ids
+        )
 
         num_entries = unattached_geometries.count()
         if num_entries > 0:
@@ -218,7 +252,7 @@ class Command(BaseKonovaCommand):
             self._write_success("No unattached geometries found.")
         self._break_line()
 
-    def get_all_state_ids(self, cls):
+    def _get_all_state_ids(self, cls):
         """ Getter for all states (before and after) of a class
 
         Args:
@@ -254,14 +288,19 @@ class Command(BaseKonovaCommand):
         """
         self._write_warning("=== Sanitize compensation states ===")
         all_states = CompensationState.objects.all()
-        compensation_state_ids = self.get_all_state_ids(Compensation)
+
-        account_state_ids = self.get_all_state_ids(EcoAccount)
+        kom_state_ids = self._get_all_state_ids(Compensation)
-        ema_state_ids = self.get_all_state_ids(Ema)
+        oek_state_ids = self._get_all_state_ids(EcoAccount)
-        attached_state_ids = compensation_state_ids.union(account_state_ids, ema_state_ids)
+        ema_state_ids = self._get_all_state_ids(Ema)
 
         unattached_states = all_states.exclude(
-            id__in=attached_state_ids
+            id__in=kom_state_ids
+        ).exclude(
+            id__in=oek_state_ids
+        ).exclude(
+            id__in=ema_state_ids
         )
+
         num_unattached_states = unattached_states.count()
         if num_unattached_states > 0:
             self._write_error(f"Found {num_unattached_states} unused compensation states. Delete now...")

konova/migrations/0015_geometry_parcel_calculation_end_and_more.py

@@ -0,0 +1,23 @@
+# Generated by Django 5.0.1 on 2024-01-09 10:38
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('konova', '0014_resubmission'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='geometry',
+            name='parcel_update_end',
+            field=models.DateTimeField(blank=True, db_comment='When the last parcel calculation finished', help_text='When the last parcel calculation finished', null=True),
+        ),
+        migrations.AddField(
+            model_name='geometry',
+            name='parcel_update_start',
+            field=models.DateTimeField(blank=True, db_comment='When the last parcel calculation started', help_text='When the last parcel calculation started', null=True),
+        ),
+    ]

konova/models/geometry.py

@@ -14,13 +14,24 @@ from django.utils import timezone
 from konova.models import BaseResource, UuidModel
 from konova.sub_settings.lanis_settings import DEFAULT_SRID_RLP
 from konova.utils.schneider.fetcher import ParcelFetcher
-from konova.utils.wfs.spatial import ParcelWFSFetcher
 
 
 class Geometry(BaseResource):
     """
     Geometry model
     """
+    parcel_update_start = models.DateTimeField(
+        blank=True,
+        null=True,
+        db_comment="When the last parcel calculation started",
+        help_text="When the last parcel calculation started"
+    )
+    parcel_update_end = models.DateTimeField(
+        blank=True,
+        null=True,
+        db_comment="When the last parcel calculation finished",
+        help_text="When the last parcel calculation finished",
+    )
     geom = MultiPolygonField(null=True, blank=True, srid=DEFAULT_SRID_RLP)
 
     def __str__(self):
@@ -109,82 +120,14 @@ class Geometry(BaseResource):
             objs += set_objs
         return objs
 
-    @transaction.atomic
+    def get_data_object(self):
-    def update_parcels_wfs(self):
-        """ Updates underlying parcel information using the WFS of LVermGeo
-
-        Returns:
-
         """
-        from konova.models import Parcel, District, ParcelIntersection, Municipal, ParcelGroup
+        Getter for the specific data object which is related to this geometry
-
+        """
-        if self.geom.empty:
+        objs = self.get_data_objects()
-            # Nothing to do
+        assert (len(objs) <= 1)
-            return
+        result = objs.pop()
-
+        return result
-        parcel_fetcher = ParcelWFSFetcher(
-            geometry_id=self.id,
-        )
-        typename = "ave:Flurstueck"
-        fetched_parcels = parcel_fetcher.get_features(
-            typename
-        )
-        _now = timezone.now()
-        underlying_parcels = []
-        for result in fetched_parcels:
-            parcel_properties = result["properties"]
-            # There could be parcels which include the word 'Flur',
-            # which needs to be deleted and just keep the numerical values
-            ## THIS CAN BE REMOVED IN THE FUTURE, WHEN 'Flur' WON'T OCCUR ANYMORE!
-            flr_val = parcel_properties["flur"].replace("Flur ", "")
-            district = District.objects.get_or_create(
-                key=parcel_properties["kreisschl"],
-                name=parcel_properties["kreis"],
-            )[0]
-            municipal = Municipal.objects.get_or_create(
-                key=parcel_properties["gmdschl"],
-                name=parcel_properties["gemeinde"],
-                district=district,
-            )[0]
-            parcel_group = ParcelGroup.objects.get_or_create(
-                key=parcel_properties["gemaschl"],
-                name=parcel_properties["gemarkung"],
-                municipal=municipal,
-            )[0]
-            flrstck_nnr = parcel_properties['flstnrnen']
-            if not flrstck_nnr:
-                flrstck_nnr = None
-            flrstck_zhlr = parcel_properties['flstnrzae']
-            if not flrstck_zhlr:
-                flrstck_zhlr = None
-            parcel_obj = Parcel.objects.get_or_create(
-                district=district,
-                municipal=municipal,
-                parcel_group=parcel_group,
-                flr=flr_val,
-                flrstck_nnr=flrstck_nnr,
-                flrstck_zhlr=flrstck_zhlr,
-            )[0]
-            parcel_obj.district = district
-            parcel_obj.updated_on = _now
-            parcel_obj.save()
-            underlying_parcels.append(parcel_obj)
-
-        # Update the linked parcels
-        self.parcels.clear()
-        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 update_parcels(self):
         """ Updates underlying parcel information
@@ -192,20 +135,28 @@ class Geometry(BaseResource):
         Returns:
 
         """
-        from konova.models import Parcel, District, ParcelIntersection, Municipal, ParcelGroup
-
         if self.geom.empty:
             # Nothing to do
             return
 
+        self._set_parcel_update_start_time()
+        self._perform_parcel_update()
+        self._set_parcel_update_end_time()
+
+    def _perform_parcel_update(self):
+        """
+        Performs the main logic of parcel updating.
+        """
+        from konova.models import Parcel, District, ParcelIntersection, Municipal, ParcelGroup
+
         parcel_fetcher = ParcelFetcher(
             geometry=self
         )
         fetched_parcels = parcel_fetcher.get_parcels()
-
         _now = timezone.now()
         underlying_parcels = []
         for result in fetched_parcels:
+            with transaction.atomic():
                 # There could be parcels which include the word 'Flur',
                 # which needs to be deleted and just keep the numerical values
                 ## THIS CAN BE REMOVED IN THE FUTURE, WHEN 'Flur' WON'T OCCUR ANYMORE!
@@ -259,6 +210,23 @@ class Geometry(BaseResource):
             ["calculated_on"]
         )
 
+    @transaction.atomic
+    def _set_parcel_update_start_time(self):
+        """
+        Sets the current time for the parcel calculation begin
+        """
+        self.parcel_update_start = timezone.now()
+        self.parcel_update_end = None
+        self.save()
+
+    @transaction.atomic
+    def _set_parcel_update_end_time(self):
+        """
+        Sets the current time for the parcel calculation end
+        """
+        self.parcel_update_end = timezone.now()
+        self.save()
+
     def get_underlying_parcels(self):
         """ Getter for related parcels and their districts
 

konova/settings.py

@@ -46,4 +46,8 @@ DEFAULT_GROUP = "Default"
 ZB_GROUP = "Registration office"
 ETS_GROUP = "Conservation office"
 
+# GEOMETRY
+## Max number of allowed vertices. Geometries larger will be simplified until they reach this threshold
 GEOM_MAX_VERTICES = 10000
+## Max seconds to wait for a parcel calculation result before a new request will be started (default: 5 minutes)
+GEOM_THRESHOLD_RECALCULATION_SECONDS = 300

konova/utils/schneider/fetcher.py

@@ -28,7 +28,11 @@ class ParcelFetcher:
         self.geometry = geometry
 
         # Reduce size of geometry to avoid "intersections" because of exact border matching
-        geom = geometry.geom.buffer(-0.001)
+        buffer_threshold = 0.001
+        geom = geometry.geom.buffer(-buffer_threshold)
+        if geom.area < buffer_threshold:
+            # Fallback for malicious geometries which are way too small but would disappear on buffering
+            geom = geometry.geom
         self.geojson = geom.ewkt
         self.results = []
 

konova/utils/wfs/spatial.py

@@ -1,189 +0,0 @@
-"""
-Author: Michel Peltriaux
-Organization: Struktur- und Genehmigungsdirektion Nord, Rhineland-Palatinate, Germany
-Contact: michel.peltriaux@sgdnord.rlp.de
-Created on: 17.12.21
-
-"""
-import json
-from abc import abstractmethod
-from json import JSONDecodeError
-from time import sleep
-
-import requests
-from django.contrib.gis.db.models.functions import AsGML, MakeValid
-from django.db.models import Func, F
-from requests.auth import HTTPDigestAuth
-
-from konova.settings import PARCEL_WFS_USER, PARCEL_WFS_PW, PROXIES
-
-
-class AbstractWFSFetcher:
-    """ Base class for fetching WFS data
-
-    """
-    # base_url represents not the capabilities url but the parameter-free base url
-    base_url = None
-    version = None
-    auth_user = None
-    auth_pw = None
-    auth_digest_obj = None
-
-    class Meta:
-        abstract = True
-
-    def __init__(self, base_url: str, version: str = "1.1.0", auth_user: str = None, auth_pw: str = None, *args, **kwargs):
-        self.base_url = base_url
-        self.version = version
-        self.auth_pw = auth_pw
-        self.auth_user = auth_user
-
-        self._create_auth_obj()
-
-    def _create_auth_obj(self):
-        if self.auth_pw is not None and self.auth_user is not None:
-            self.auth_digest_obj = HTTPDigestAuth(
-                self.auth_user,
-                self.auth_pw
-            )
-
-    @abstractmethod
-    def get_features(self, feature_identifier: str, filter_str: str):
-        raise NotImplementedError
-
-
-class ParcelWFSFetcher(AbstractWFSFetcher):
-    """ Fetches features from a special parcel WFS
-
-    """
-    geometry_id = None
-    geometry_property_name = None
-    count = 100
-
-    def __init__(self, geometry_id: str, geometry_property_name: str = "msGeometry", *args, **kwargs):
-        super().__init__(
-            version="2.0.0",
-            base_url="https://www.geoportal.rlp.de/registry/wfs/519",
-            auth_user=PARCEL_WFS_USER,
-            auth_pw=PARCEL_WFS_PW,
-            *args,
-            **kwargs
-        )
-        self.geometry_id = geometry_id
-        self.geometry_property_name = geometry_property_name
-
-    def _create_spatial_filter(self,
-                               geometry_operation: str):
-        """ Creates a xml spatial filter according to the WFS filter specification
-
-        The geometry needs to be shrinked by a very small factor (-0.01) before a GML can be created for intersection
-        checking. Otherwise perfect parcel outline placement on top of a neighbouring parcel would result in an
-        intersection hit, despite the fact they do not truly intersect just because their vertices match.
-
-        Args:
-            geometry_operation (str): One of the WFS supported spatial filter operations (according to capabilities)
-
-        Returns:
-            spatial_filter (str): The spatial filter element
-        """
-        from konova.models import Geometry
-
-        geom = Geometry.objects.filter(
-            id=self.geometry_id
-        ).annotate(
-            smaller=Func(F('geom'), -0.001, function="ST_Buffer")  # same as geometry.geom_small_buffered but for QuerySet
-        ).annotate(
-            gml=AsGML(MakeValid('smaller'))
-        ).first()
-        geom_gml = geom.gml
-        spatial_filter = f"<Filter><{geometry_operation}><PropertyName>{self.geometry_property_name}</PropertyName>{geom_gml}</{geometry_operation}></Filter>"
-        return spatial_filter
-
-    def _create_post_data(self,
-                          geometry_operation: str,
-                          typenames: str = None,
-                          start_index: int = 0,
-                          ):
-        """ Creates a POST body content for fetching features
-
-        Args:
-            geometry_operation (str): One of the WFS supported spatial filter operations (according to capabilities)
-
-        Returns:
-            _filter (str): A proper xml WFS filter
-        """
-        start_index = str(start_index)
-        spatial_filter = self._create_spatial_filter(
-            geometry_operation
-        )
-        _filter = f'<wfs:GetFeature service="WFS" version="{self.version}" xmlns:wfs="http://www.opengis.net/wfs/2.0" xmlns:fes="http://www.opengis.net/fes/2.0" xmlns:myns="http://www.someserver.com/myns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/wfs/2.0 http://schemas.opengis.net/wfs/2.0.0/wfs.xsd" count="{self.count}" startindex="{start_index}" outputFormat="application/json; subtype=geojson"><wfs:Query typeNames="{typenames}">{spatial_filter}</wfs:Query></wfs:GetFeature>'
-        return _filter
-
-    def get_features(self,
-                     typenames: str,
-                     spatial_operator: str = "Intersects",
-                     filter_srid: str = None,
-                     start_index: int = 0,
-                     rerun_on_exception: bool = True
-                     ):
-        """ Fetches features from the WFS using POST
-
-        POST is required since GET has a character limit around 4000. Having a larger filter would result in errors,
-        which do not occur in case of POST.
-
-        Args:
-            typenames (str): References to parameter 'typenames' in a WFS GetFeature request
-            spatial_operator (str): Defines the spatial operation for filtering
-            filter_srid (str): Defines the spatial reference system, the geometry shall be transformed into for filtering
-            start_index (str): References to parameter 'startindex' in a
-
-        Returns:
-            features (list): A list of returned features
-        """
-        found_features = []
-        while start_index is not None:
-            post_body = self._create_post_data(
-                spatial_operator,
-                typenames,
-                start_index
-            )
-            response = requests.post(
-                url=self.base_url,
-                data=post_body,
-                auth=self.auth_digest_obj,
-                proxies=PROXIES,
-            )
-
-            content = response.content.decode("utf-8")
-            try:
-                # Check if collection is an exception and does not contain the requested data
-                content = json.loads(content)
-            except JSONDecodeError as e:
-                if rerun_on_exception:
-                    # Wait a second before another try
-                    sleep(1)
-                    self.get_features(
-                        typenames,
-                        spatial_operator,
-                        filter_srid,
-                        start_index,
-                        rerun_on_exception=False
-                    )
-                else:
-                    e.msg += content
-                    raise e
-            fetched_features = content.get(
-                "features",
-                {},
-            )
-
-            found_features += fetched_features
-
-            if len(fetched_features) < self.count:
-                # The response was not 'full', so we got everything to fetch
-                start_index = None
-            else:
-                # If a 'full' response returned, there might be more to fetch. Increase the start_index!
-                start_index += self.count
-
-        return found_features

konova/views/geometry.py

@@ -10,10 +10,13 @@ from django.contrib.gis.geos import MultiPolygon
 from django.http import HttpResponse, HttpRequest
 from django.shortcuts import get_object_or_404
 from django.template.loader import render_to_string
+from django.utils import timezone
 from django.views import View
 
 from konova.models import Geometry
+from konova.settings import GEOM_THRESHOLD_RECALCULATION_SECONDS
 from konova.sub_settings.lanis_settings import DEFAULT_SRID_RLP
+from konova.tasks import celery_update_parcels
 
 
 class GeomParcelsView(LoginRequiredMixin, View):
@@ -38,15 +41,25 @@ class GeomParcelsView(LoginRequiredMixin, View):
         parcels = geom.get_underlying_parcels()
         geos_geom = geom.geom or MultiPolygon(srid=DEFAULT_SRID_RLP)
 
-        geometry_exists = not geos_geom.empty
+        waiting_too_long = self._check_waiting_too_long(geom)
-        parcels_are_currently_calculated = geometry_exists and geos_geom.area > 0 and len(parcels) == 0
+
+        geometry_exists = not geos_geom.empty and geos_geom.area > 0
+        parcels_are_currently_calculated = (
+                geometry_exists and
+                geom.parcel_update_start and
+                not geom.parcel_update_end
+        )
         parcels_available = len(parcels) > 0
 
         if parcels_are_currently_calculated:
             # Parcels are being calculated right now. Change the status code, so polling stays active for fetching
-            # resutls after the calculation
+            # results after the calculation
             status_code = 200
 
+        if waiting_too_long:
+            # Trigger calculation again
+            celery_update_parcels.delay(geom.id)
+
         if parcels_available or not geometry_exists:
             municipals = geom.get_underlying_municipals(parcels)
 
@@ -69,6 +82,21 @@ class GeomParcelsView(LoginRequiredMixin, View):
         else:
             return HttpResponse(None, status=404)
 
+    def _check_waiting_too_long(self, geom: Geometry):
+        """ Check whether the client is waiting too long for a parcel calculation result
+
+        Depending on the geometry's modified attribute
+
+        """
+        try:
+            pcs_diff = (timezone.now() - geom.parcel_update_start).seconds
+        except TypeError:
+            pcs_diff = GEOM_THRESHOLD_RECALCULATION_SECONDS
+
+        calculation_not_finished = geom.parcel_update_end is None
+        waiting_too_long = (pcs_diff >= GEOM_THRESHOLD_RECALCULATION_SECONDS) and calculation_not_finished
+        return waiting_too_long
+
 
 class GeomParcelsContentView(LoginRequiredMixin, View):
 

requirements.txt

@@ -34,7 +34,6 @@ pika==1.3.2
 prompt-toolkit==3.0.43
 psycopg==3.1.16
 psycopg-binary==3.1.16
-psycopg2-binary==2.9.9
 pyparsing==3.1.1
 pypng==0.20220715.0
 pyproj==3.6.1