Improve notification of 'low stock' parts:

- Traverse up the variant tree
- Enable subscription by "category"

InvenTree/part/models.py

@@ -20,7 +20,7 @@ from django.db.models.functions import Coalesce
 from django.core.validators import MinValueValidator
 
 from django.contrib.auth.models import User
-from django.db.models.signals import pre_delete
+from django.db.models.signals import pre_delete, post_save
 from django.dispatch import receiver
 
 from jinja2 import Template
@@ -47,6 +47,7 @@ from InvenTree import validators
 from InvenTree.models import InvenTreeTree, InvenTreeAttachment
 from InvenTree.fields import InvenTreeURLField
 from InvenTree.helpers import decimal2string, normalize, decimal2money
+import InvenTree.tasks
 
 from InvenTree.status_codes import BuildStatus, PurchaseOrderStatus, SalesOrderStatus
 
@@ -56,6 +57,7 @@ from company.models import SupplierPart
 from stock import models as StockModels
 
 import common.models
+
 import part.settings as part_settings
 
 
@@ -2085,9 +2087,24 @@ class Part(MPTTModel):
         return len(self.get_related_parts())
 
     def is_part_low_on_stock(self):
+        """
+        Returns True if the total stock for this part is less than the minimum stock level
+        """
+        
         return self.total_stock <= self.minimum_stock
 
 
+
+@receiver(post_save, sender=Part, dispatch_uid='part_post_save_log')
+def after_save_part(sender, instance: Part, **kwargs):
+    """
+    Function to be executed after a Part is saved
+    """
+
+    # Run this check in the background
+    InvenTree.tasks.offload_task('part.tasks.notify_low_stock_if_required', instance)
+
+
 def attach_file(instance, filename):
     """ Function for storing a file for a PartAttachment
 

InvenTree/part/tasks.py

@@ -13,23 +13,28 @@ from common.models import InvenTree
 import InvenTree.helpers
 import InvenTree.tasks
 
-from part.models import Part
+import part.models
 
 logger = logging.getLogger("inventree")
 
 
-def notify_low_stock(part: Part):
+def notify_low_stock(part: part.models.Part):
     """
     Notify users who have starred a part when its stock quantity falls below the minimum threshold
     """
 
     logger.info(f"Sending low stock notification email for {part.full_name}")
 
-    starred_users_email = EmailAddress.objects.filter(user__starred_parts__part=part)
+    # Get a list of users who are subcribed to this part
+    subscribers = part.get_subscribers()
+
+    emails = EmailAddress.objects.filter(
+        user__in=subscribers,
+    )
 
     # TODO: In the future, include the part image in the email template
 
-    if len(starred_users_email) > 0:
+    if len(emails) > 0:
         logger.info(f"Notify users regarding low stock of {part.name}")
         context = {
             # Pass the "Part" object through to the template context
@@ -39,20 +44,24 @@ def notify_low_stock(part: Part):
 
         subject = _(f'[InvenTree] {part.name} is low on stock')
         html_message = render_to_string('email/low_stock_notification.html', context)
-        recipients = starred_users_email.values_list('email', flat=True)
+        recipients = emails.values_list('email', flat=True)
 
         InvenTree.tasks.send_email(subject, '', recipients, html_message=html_message)
 
 
-def notify_low_stock_if_required(part: Part):
+def notify_low_stock_if_required(part: part.models.Part):
     """
     Check if the stock quantity has fallen below the minimum threshold of part.
     
     If true, notify the users who have subscribed to the part
     """
 
-    if part.is_part_low_on_stock():
+    # Run "up" the tree, to allow notification for "parent" parts
+    parts = part.get_ancestors(include_self=True, ascending=True)
+
+    for p in parts:
+        if p.is_part_low_on_stock():
             InvenTree.tasks.offload_task(
                 'part.tasks.notify_low_stock',
-            part
+                p
             )

InvenTree/stock/models.py

@@ -27,7 +27,9 @@ from mptt.managers import TreeManager
 
 from decimal import Decimal, InvalidOperation
 from datetime import datetime, timedelta
+
 from InvenTree import helpers
+import InvenTree.tasks
 
 import common.models
 import report.models
@@ -41,7 +43,6 @@ from users.models import Owner
 
 from company import models as CompanyModels
 from part import models as PartModels
-from part import tasks as part_tasks
 
 
 class StockLocation(InvenTreeTree):
@@ -1658,7 +1659,8 @@ def after_delete_stock_item(sender, instance: StockItem, **kwargs):
     Function to be executed after a StockItem object is deleted
     """
 
-    part_tasks.notify_low_stock_if_required(instance.part)
+    # Run this check in the background
+    InvenTree.tasks.offload_task('part.tasks.notify_low_stock_if_required', instance.part)
 
 
 @receiver(post_save, sender=StockItem, dispatch_uid='stock_item_post_save_log')
@@ -1667,7 +1669,8 @@ def after_save_stock_item(sender, instance: StockItem, **kwargs):
     Hook function to be executed after StockItem object is saved/updated
     """
 
-    part_tasks.notify_low_stock_if_required(instance.part)
+    # Run this check in the background
+    InvenTree.tasks.offload_task('part.tasks.notify_low_stock_if_required', instance.part)
 
 
 class StockItemAttachment(InvenTreeAttachment):

InvenTree/templates/email/low_stock_notification.html

@@ -17,13 +17,15 @@
 {% block body %}
 <tr style="height: 3rem; border-bottom: 1px solid">
     <th>{% trans "Part Name" %}</th>
-    <th>{% trans "Available Quantity" %}</th>
+    <th>{% trans "Total Stock" %}</th>
+    <th>{% trans "Available" %}</th>
     <th>{% trans "Minimum Quantity" %}</th>
 </tr>
 
 <tr style="height: 3rem">
     <td style="text-align: center;">{{ part.full_name }}</td>
     <td style="text-align: center;">{{ part.total_stock }}</td>
+    <td style="text-align: center;">{{ part.available_stock }}</td>
     <td style="text-align: center;">{{ part.minimum_stock }}</td>
 </tr>
 {% endblock %}