Prevent an incident from having relations with itself

src/argus/incident/migrations/0004_incidentrelation_prevent_loop.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.5 on 2021-08-19 09:19
+
+from django.db import migrations, models
+import django.db.models.expressions
+
+
+class Migration(migrations.Migration):
+
+ dependencies = [
+ ('argus_incident', '0003_incident_level'),
+ ]
+
+ operations = [
+ migrations.AddConstraint(
+ model_name='incidentrelation',
+ constraint=models.CheckConstraint(check=models.Q(('incident1', django.db.models.expressions.F('incident2')), _negated=True), name='incidentrelation_prevent_loop'),
+ ),
+ ]

src/argus/incident/models.py

@@ -359,6 +359,13 @@ class IncidentRelation(models.Model):
  type = models.ForeignKey(to=IncidentRelationType, on_delete=models.PROTECT, related_name="incident_relations")
  description = models.TextField(blank=True)
 
+ class Meta:
+ constraints = [
+ models.CheckConstraint(
+ check=~models.Q(incident1=models.F("incident2")), name="incidentrelation_prevent_loop"
+ ),
+ ]
+
  def __str__(self):
  return f"Incident #{self.incident1.pk} {self.type} #{self.incident2.pk}"