From 80c7ee6dab8f64310c99b6963f560c77aa4eeea0 Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Fri, 8 Jan 2021 22:47:47 +1100
Subject: [PATCH] Add ability to filter label by StockItem

---
 InvenTree/label/api.py    | 90 +++++++++++++++++++++++++++++++++++++++
 InvenTree/label/models.py |  6 ++-
 2 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/InvenTree/label/api.py b/InvenTree/label/api.py
index 539851285a..c56bae59ca 100644
--- a/InvenTree/label/api.py
+++ b/InvenTree/label/api.py
@@ -7,6 +7,10 @@ from django_filters.rest_framework import DjangoFilterBackend
 
 from rest_framework import generics, filters
 
+import InvenTree.helpers
+
+from stock.models import StockItem
+
 from .models import StockItemLabel
 from .serializers import StockItemLabelSerializer
 
@@ -14,11 +18,97 @@ from .serializers import StockItemLabelSerializer
 class StockItemLabelList(generics.ListAPIView):
     """
     API endpoint for viewing list of StockItemLabel objects.
+
+    Filterable by:
+
+    - enabled: Filter by enabled / disabled status
+    - item: Filter by single stock item
+    - items[]: Filter by list of stock items
+
     """
 
     queryset = StockItemLabel.objects.all()
     serializer_class = StockItemLabelSerializer
 
+    def get_items(self):
+        """
+        Return a list of requested stock items
+        """
+
+        items = []
+
+        params = self.request.query_params
+
+        if 'items' in params:
+            items = params.getlist('items', [])
+        elif 'item' in params:
+            items = [params.get('item', None)]
+
+        if type(items) not in [list, tuple]:
+            items = [items]
+
+        valid_ids = []
+
+        for item in items:
+            try:
+                valid_ids.append(int(item))
+            except (ValueError):
+                pass
+
+        # List of StockItems which match provided values
+        valid_items = StockItem.objects.filter(pk__in=valid_ids)
+
+        return valid_items
+
+    def filter_queryset(self, queryset):
+        """
+        Filter the StockItem label queryset.
+        """
+        
+        queryset = super().filter_queryset(queryset)
+
+        # List of StockItem objects to match against
+        items = self.get_items()
+
+        # We wish to filter by stock items
+        if len(items) > 0:
+            """
+            At this point, we are basically forced to be inefficient,
+            as we need to compare the 'filters' string of each label,
+            and see if it matches against each of the requested items.
+
+            TODO: In the future, if this becomes excessively slow, it
+                  will need to be readdressed.
+            """
+
+            # Keep track of which labels match every specified stockitem
+            valid_label_ids = set()
+            
+            for label in queryset.all():
+
+                matches = True
+
+                # Filter string defined for the StockItem label
+                filters = InvenTree.helpers.validateFilterString(label.filters)
+
+                for item in items:
+
+                    item_query = StockItem.objects.filter(pk=item.pk)
+
+                    if not item_query.filter(**filters).exists():
+                        matches = False
+
+                # Matched all items
+                if matches:
+                    valid_label_ids.add(label.pk)
+                else:
+                    continue
+
+            # Reduce queryset to only valid matches
+            queryset = queryset.filter(pk__in=[id for id in valid_label_ids])
+
+        return queryset
+
     filter_backends = [
         DjangoFilterBackend,
         filters.SearchFilter
diff --git a/InvenTree/label/models.py b/InvenTree/label/models.py
index 49b07572a8..8d4f2cd2f4 100644
--- a/InvenTree/label/models.py
+++ b/InvenTree/label/models.py
@@ -55,7 +55,11 @@ class LabelTemplate(models.Model):
         help_text=_('Label name'),
     )
 
-    description = models.CharField(max_length=250, help_text=_('Label description'), blank=True, null=True)
+    description = models.CharField(
+        max_length=250,
+        blank=True, null=True,
+        help_text=_('Label description'),
+    )
 
     label = models.FileField(
         upload_to=rename_label,