[feature] Batch email notifications

README.rst

@@ -1014,7 +1014,7 @@ The default configuration is as follows:
     }
 
 ``OPENWISP_NOTIFICATIONS_EMAIL_BATCH_INTERVAL``
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 +---------+-----------------------------------+
 | type    | ``int``                           |
@@ -1026,6 +1026,17 @@ This setting defines the interval at which the email notifications are sent in b
 
 If you want to send email notifications immediately, then set it to ``0``.
 
+``OPENWISP_NOTIFICATIONS_EMAIL_BATCH_DISPLAY_LIMIT``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
++---------+-----------------------------------+
+| type    | ``int``                           |
++---------+-----------------------------------+
+| default | ``15``                            |
++---------+-----------------------------------+
+
+This setting defines the number of email notifications to be displayed in a batched email.
+
 Exceptions
 ----------
 

openwisp_notifications/handlers.py

@@ -25,7 +25,7 @@
 logger = logging.getLogger(__name__)
 
 EXTRA_DATA = app_settings.get_config()['USE_JSONFIELD']
-EMAIL_BATCH_INTERVAL = app_settings.OPENWISP_NOTIFICATIONS_EMAIL_BATCH_INTERVAL
+EMAIL_BATCH_INTERVAL = app_settings.EMAIL_BATCH_INTERVAL
 
 User = get_user_model()
 
@@ -201,6 +201,7 @@ def send_email_notification(sender, instance, created, **kwargs):
             'last_email_sent_time': None,
             'batch_scheduled': False,
             'pks': [],
+            'start_time': None,
             'email_id': instance.recipient.email,
         },
     )
@@ -209,12 +210,13 @@ def send_email_notification(sender, instance, created, **kwargs):
         # Case 1: Batch email sending logic
         if not cache_data['batch_scheduled']:
             # Schedule batch email notification task if not already scheduled
-            tasks.batch_email_notification.apply_async(
+            tasks.send_batched_email_notifications.apply_async(
                 (instance.recipient.id,), countdown=EMAIL_BATCH_INTERVAL
             )
             # Mark batch as scheduled to prevent duplicate scheduling
             cache_data['batch_scheduled'] = True
             cache_data['pks'] = [instance.id]
+            cache_data['start_time'] = timezone.now()
             cache.set(cache_key, cache_data)
         else:
             # Add current instance ID to the list of IDs for batch
@@ -224,8 +226,9 @@ def send_email_notification(sender, instance, created, **kwargs):
 
     # Case 2: Single email sending logic
     # Update the last email sent time and cache the data
-    cache_data['last_email_sent_time'] = timezone.now()
-    cache.set(cache_key, cache_data, timeout=EMAIL_BATCH_INTERVAL)
+    if EMAIL_BATCH_INTERVAL > 0:
+        cache_data['last_email_sent_time'] = timezone.now()
+        cache.set(cache_key, cache_data, timeout=EMAIL_BATCH_INTERVAL)
 
     send_notification_email(instance)
 

openwisp_notifications/settings.py

@@ -37,10 +37,14 @@
     'openwisp-notifications/audio/notification_bell.mp3',
 )
 
-OPENWISP_NOTIFICATIONS_EMAIL_BATCH_INTERVAL = getattr(
+EMAIL_BATCH_INTERVAL = getattr(
     settings, 'OPENWISP_NOTIFICATIONS_EMAIL_BATCH_INTERVAL', 30 * 60  # 30 minutes
 )
 
+EMAIL_BATCH_DISPLAY_LIMIT = getattr(
+    settings, 'OPENWISP_NOTIFICATIONS_EMAIL_BATCH_DISPLAY_LIMIT', 15
+)
+
 # Remove the leading "/static/" here as it will
 # conflict with the "static()" call in context_processors.py.
 # This is done for backward compatibility.

openwisp_notifications/tasks.py

@@ -9,6 +9,7 @@
 from django.db.utils import OperationalError
 from django.template.loader import render_to_string
 from django.utils import timezone
+from django.utils.translation import gettext as _
 
 from openwisp_notifications import settings as app_settings
 from openwisp_notifications import types
@@ -17,7 +18,7 @@
 from openwisp_utils.admin_theme.email import send_email
 from openwisp_utils.tasks import OpenwispCeleryTask
 
-EMAIL_BATCH_INTERVAL = app_settings.OPENWISP_NOTIFICATIONS_EMAIL_BATCH_INTERVAL
+EMAIL_BATCH_INTERVAL = app_settings.EMAIL_BATCH_INTERVAL
 
 User = get_user_model()
 
@@ -213,7 +214,7 @@ def delete_ignore_object_notification(instance_id):
 
 
 @shared_task(base=OpenwispCeleryTask)
-def batch_email_notification(instance_id):
+def send_batched_email_notifications(instance_id):
     """
     Sends a summary of notifications to the specified email address.
     """
@@ -226,7 +227,10 @@ def batch_email_notification(instance_id):
     if not cache_data['pks']:
         return
 
-    unsent_notifications = Notification.objects.filter(id__in=cache_data['pks'])
+    display_limit = app_settings.EMAIL_BATCH_DISPLAY_LIMIT
+    unsent_notifications = Notification.objects.filter(
+        id__in=cache_data['pks']
+    ).order_by('-timestamp')
     notifications_count = unsent_notifications.count()
     current_site = Site.objects.get_current()
     email_id = cache_data.get('email_id')
@@ -236,8 +240,8 @@ def batch_email_notification(instance_id):
         notification = unsent_notifications.first()
         send_notification_email(notification)
     else:
-        # Show notification description upto 5 notifications
-        show_notification_description = notifications_count <= 5
+        # Show the amount of notifications according to configured display limit
+        show_notification_description = notifications_count <= display_limit
         for notification in unsent_notifications:
             url = notification.data.get('url', '') if notification.data else None
             if url:
@@ -247,24 +251,33 @@ def batch_email_notification(instance_id):
             else:
                 notification.url = None
 
+        starting_time = (
+            cache_data.get('start_time')
+            .strftime('%B %-d, %Y, %-I:%M %p')
+            .lower()
+            .replace('am', 'a.m.')
+            .replace('pm', 'p.m.')
+        ) + ' UTC'
+
         context = {
             'notifications': unsent_notifications,
             'notifications_count': notifications_count,
             'show_notification_description': show_notification_description,
             'site_name': current_site.name,
+            'start_time': starting_time,
         }
         html_content = render_to_string('emails/batch_email.html', context)
         plain_text_content = render_to_string('emails/batch_email.txt', context)
 
         extra_context = {}
-        if notifications_count > 5:
+        if notifications_count > display_limit:
             extra_context = {
                 'call_to_action_url': f"https://{current_site.domain}/admin",
-                'call_to_action_text': 'View all Notifications',
+                'call_to_action_text': _('View all Notifications'),
             }
 
         send_email(
-            subject=f'Summary of {notifications_count} Notifications from {current_site.name}',
+            subject=f'[{current_site.name}] {notifications_count} new notifications since {starting_time}',
             body_text=plain_text_content,
             body_html=html_content,
             recipients=[email_id],

openwisp_notifications/templates/emails/batch_email.txt

@@ -1,15 +1,16 @@
-Summary of {{ notifications_count }} Notifications from {{ site_name }}
+{% load i18n %}
+
+[{{ site_name }}] {{ notifications_count }} {% translate "new notifications since" %} {{ start_time }}
 
 {% for notification in notifications %}
 - {{ notification.message }}
-  URL: {{ notification.url }}
-  Timestamp: {{ notification.timestamp|date:"F j, Y, g:i a" }}
+  {% translate "URL" %}: {{ notification.url }}
+  {% translate "Timestamp" %}: {{ notification.timestamp|date:"F j, Y, g:i a" }}
   {% if show_notification_description %}
-      Description: {{ notification.rendered_description }}
+      {% translate "Description" %}: {{ notification.rendered_description }}
   {% endif %}
 {% endfor %}
 
-{% if notifications_count > 5 %}
-View all Notifications: {{ call_to_action_url }}
+{% if not show_notification_description  %}
+{% translate "View all Notifications" %}: {{ call_to_action_url }}
 {% endif %}
-

openwisp_notifications/tests/test_notifications.py

@@ -11,7 +11,7 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.db.models.signals import post_migrate, post_save
 from django.template import TemplateDoesNotExist
-from django.test import TransactionTestCase
+from django.test import TransactionTestCase, override_settings
 from django.urls import reverse
 from django.utils import timezone
 from django.utils.timesince import timesince
@@ -944,7 +944,7 @@ def test_notification_for_unverified_email(self):
         # we don't send emails to unverified email addresses
         self.assertEqual(len(mail.outbox), 0)
 
-    @patch('openwisp_notifications.tasks.batch_email_notification.apply_async')
+    @patch('openwisp_notifications.tasks.send_batched_email_notifications.apply_async')
     def test_batch_email_notification_with_descriptions(self, mock_send_email):
         for _ in range(5):
             notify.send(recipient=self.admin, **self.notification_options)
@@ -953,37 +953,50 @@ def test_batch_email_notification_with_descriptions(self, mock_send_email):
         self.assertEqual(len(mail.outbox), 1)
 
         # Call the task
-        tasks.batch_email_notification(self.admin.id)
+        tasks.send_batched_email_notifications(self.admin.id)
 
         # Check if the rest of the notifications are sent in a batch
         self.assertEqual(len(mail.outbox), 2)
-        self.assertIn('Summary of 4 Notifications', mail.outbox[1].subject)
+        self.assertIn('4 new notifications since', mail.outbox[1].subject)
         self.assertNotIn('View all Notifications', mail.outbox[1].body)
         self.assertIn('Test Notification', mail.outbox[1].body)
 
-    @patch('openwisp_notifications.tasks.batch_email_notification.apply_async')
+    @patch('openwisp_notifications.tasks.send_batched_email_notifications.apply_async')
     def test_batch_email_notification_with_call_to_action(self, mock_send_email):
         self.notification_options.update(
             {
                 'message': 'Notification title',
                 'type': 'default',
             }
         )
-        for _ in range(11):
+        for _ in range(21):
             notify.send(recipient=self.admin, **self.notification_options)
 
         # Check if only one mail is sent initially
         self.assertEqual(len(mail.outbox), 1)
 
         # Call the task
-        tasks.batch_email_notification(self.admin.id)
+        tasks.send_batched_email_notifications(self.admin.id)
 
         # Check if the rest of the notifications are sent in a batch
         self.assertEqual(len(mail.outbox), 2)
-        self.assertIn('Summary of 10 Notifications', mail.outbox[1].subject)
+        self.assertIn('20 new notifications since', mail.outbox[1].subject)
         self.assertIn('View all Notifications', mail.outbox[1].body)
         self.assertNotIn('Test Notification', mail.outbox[1].body)
 
+    @override_settings(EMAIL_BATCH_INTERVAL=0)
+    def test_without_batch_email_notification(self):
+        self.notification_options.update(
+            {
+                'message': 'Notification title',
+                'type': 'default',
+            }
+        )
+        for _ in range(3):
+            notify.send(recipient=self.admin, **self.notification_options)
+
+        self.assertEqual(len(mail.outbox), 3)
+
     def test_that_the_notification_is_only_sent_once_to_the_user(self):
         first_org = self._create_org()
         first_org.organization_id = first_org.id

openwisp_notifications/utils.py

@@ -35,9 +35,7 @@ def normalize_unread_count(unread_count):
 
 
 def send_notification_email(notification):
-
     """Send a single email notification"""
-
     try:
         subject = notification.email_subject
     except NotificationRenderException: