Replace create default dashboard trigger with django signal

changelog.d/3585.changed.md

@@ -0,0 +1 @@
+Change default dashboard trigger to use django signal

python/nav/models/apps.py

@@ -4,3 +4,6 @@
 class NavModelsConfig(AppConfig):
     name = 'nav.models'
     verbose_name = 'NAV models'
+
+    def ready(self):
+        import nav.models.signals  # noqa

python/nav/models/signals.py

@@ -0,0 +1,32 @@
+"""
+signals.py
+
+Defines Django signal handlers for model events within the application.
+Handles actions such as creating default dashboards and navlets when new Accounts
+ are created.
+"""
+
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+from .profiles import Account, AccountDashboard, AccountNavlet
+
+
+@receiver(post_save, sender=Account)
+def create_default_dashboard(sender, instance, created, **_kwargs):
+    """
+    Signal handler that creates a default dashboard and navlets for a new Account.
+    """
+    if created:
+        dashboard = AccountDashboard.objects.create(
+            name='My dashboard', account=instance, num_columns=4, is_default=True
+        )
+        default_navlets = AccountNavlet.objects.filter(account_id=0)
+        for navlet in default_navlets:
+            AccountNavlet.objects.create(
+                account=instance,
+                navlet=navlet.navlet,
+                order=navlet.order,
+                column=navlet.column,
+                preferences=navlet.preferences,
+                dashboard=dashboard,
+            )

python/nav/models/sql/changes/sc.05.15.0002.sql

@@ -0,0 +1,5 @@
+-- Drop the trigger
+DROP TRIGGER IF EXISTS add_default_dashboard_on_account_create ON profiles.account;
+
+-- Drop the function
+DROP FUNCTION IF EXISTS create_new_dashboard() CASCADE;