clean up d3_json

epdb/models.py

@@ -1573,11 +1573,9 @@ class Pathway(EnviPathModel, AliasMixin, ScenarioMixin):
         while len(queue):
             current = queue.pop()
             processed.add(current)
-
             nodes.append(current.d3_json())
 
-            for e in self.edges:
-                if current in e.start_nodes.all():
+            for e in self.edges.filter(start_nodes=current).distinct():
                 for prod in e.end_nodes.all():
                     if prod not in queue and prod not in processed:
                         queue.append(prod)