Add task to check required stock for build order

InvenTree/build/tasks.py

@@ -0,0 +1,85 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+import logging
+
+from django.utils.translation import ugettext_lazy as _
+from django.template.loader import render_to_string
+
+from allauth.account.models import EmailAddress
+
+from common.models import NotificationEntry
+
+import build.models
+import InvenTree.helpers
+import InvenTree.tasks
+
+
+logger = logging.getLogger('inventree')
+
+
+def check_build_stock(build: build.models.Build):
+    """
+    Check the required stock for a newly created build order,
+    and send an email out to any subscribed users if stock is low.
+    """
+
+    # Iterate through each of the parts required for this build
+
+    lines = []
+
+    for bom_item in build.part.get_bom_items():
+
+        sub_part = bom_item.sub_part
+
+        # The 'in stock' quantity depends on whether the bom_item allows variants
+        in_stock = sub_part.get_stock_count(include_variants=bom_item.allow_variants)
+
+        allocated = sub_part.allocation_count()
+
+        available = max(0, in_stock - allocated)
+
+        required = bom_item.quantity * build.quantity
+
+        if available < required:
+            # There is not sufficient stock for this part
+
+            lines.append({
+                'link': InvenTree.helpers.construct_absolute_url(sub_part.get_absolute_url()),
+                'part': sub_part,
+                'in_stock': in_stock,
+                'allocated': allocated,
+                'available': available,
+                'required': required,
+            })
+
+    if len(lines) == 0:
+        # Nothing to do
+        return
+
+    # Are there any users subscribed to these parts?
+    subscribers = build.part.get_subscribers()
+
+    emails = EmailAddress.objects.filter(
+        user__in=subscribers,
+    )
+
+    if len(emails) > 0:
+
+        logger.info(f"Notifying users of stock required for build {build.pk}")
+
+        context = {
+            'link': InvenTree.helpers.construct_absolute_url(build.get_absolute_url()),
+            'build': build,
+            'part': build.part,
+            'lines': lines,
+        }
+
+        # Render the HTML message
+        html_message = render_to_string('email/build_order_required_stock.html', context)
+
+        subject = "[InvenTree] " + _("Stock required for build order")
+
+        recipients = emails.values_list('email', flat=True)
+
+        InvenTree.tasks.send_email(subject, '', recipients, html_message=html_message)