Delete Stale Edges when removing a Node from a Pathway (#41)

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#41

epdb/apps.py

@@ -4,3 +4,6 @@ from django.apps import AppConfig
 class EPDBConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'epdb'
+
+    def ready(self):
+        import epdb.signals  # noqa: F401

epdb/models.py

@@ -1044,7 +1044,7 @@ class Node(EnviPathModel, AliasMixin, ScenarioMixin):
         return IndigoUtils.mol_to_svg(self.default_node_label.smiles)
 
 
-class Edge(PolymorphicModel, EnviPathModel, AliasMixin, ScenarioMixin):
+class Edge(EnviPathModel, AliasMixin, ScenarioMixin):
     pathway = models.ForeignKey('epdb.Pathway', verbose_name='belongs to', on_delete=models.CASCADE, db_index=True)
     edge_label = models.ForeignKey('epdb.Reaction', verbose_name='Edge label', null=True, on_delete=models.SET_NULL)
     start_nodes = models.ManyToManyField('epdb.Node', verbose_name='Start Nodes', related_name='edge_educts')

epdb/signals.py

@@ -0,0 +1,20 @@
+from django.db import transaction
+from django.db.models.signals import pre_delete
+from django.dispatch import receiver
+
+from epdb.models import Node, Edge
+
+
+@receiver(pre_delete, sender=Node)
+@transaction.atomic
+def delete_orphan_edges(sender, instance, **kwargs):
+    # check if the node that is about to be deleted is the only start node
+    for edge in Edge.objects.filter(start_nodes=instance):
+        if edge.start_nodes.count() == 1:
+            edge.delete()
+
+    # same for end_nodes
+    for edge in Edge.objects.filter(end_nodes=instance):
+        # check if the node that is about to be deleted is the only start node
+        if edge.end_nodes.count() == 1:
+            edge.delete()

epdb/views.py

@@ -1417,15 +1417,20 @@ def package_pathway_node(request, package_uuid, pathway_uuid, node_uuid):
         return render(request, 'objects/node.html', context)
 
     elif request.method == 'POST':
-        if s.DEBUG:
+
-            for k, v in request.POST.items():
+        log_post_params(request)
-                print(k, v)
 
         if hidden := request.POST.get('hidden', None):
             if hidden == 'delete-node':
-                current_node.delete()
-                return redirect(current_pathway.url)
 
+                # pre_delete signal will take care of edge deletion
+                current_node.delete()
+
+                return redirect(current_pathway.url)
+            else:
+                return HttpResponseBadRequest()
+        else:
+            return HttpResponseBadRequest()
     else:
         return HttpResponseNotAllowed(['GET', 'POST'])
 
@@ -1474,6 +1479,8 @@ def package_pathway_edges(request, package_uuid, pathway_uuid):
 
     elif request.method == 'POST':
 
+        log_post_params(request)
+
         edge_name = request.POST.get('edge-name')
         edge_description = request.POST.get('edge-description')
         edge_substrates = request.POST.getlist('edge-substrates')
@@ -1517,9 +1524,8 @@ def package_pathway_edge(request, package_uuid, pathway_uuid, edge_uuid):
         return render(request, 'objects/edge.html', context)
 
     elif request.method == 'POST':
-        if s.DEBUG:
+
-            for k, v in request.POST.items():
+        log_post_params(request)
-                print(k, v)
 
         if hidden := request.POST.get('hidden', None):
             if hidden == 'delete-edge':