Defined custom SupplierPart object manager and prefetch related models in all queries

InvenTree/company/api.py

@@ -263,11 +263,7 @@ class SupplierPartList(generics.ListCreateAPIView):
     - POST: Create a new SupplierPart object
     """
 
-    queryset = SupplierPart.objects.all().prefetch_related(
-        'part',
-        'supplier',
-        'manufacturer_part__manufacturer',
-    )
+    queryset = SupplierPart.objects.all()
 
     def get_queryset(self):
 

InvenTree/company/models.py

@@ -430,6 +430,22 @@ class ManufacturerPartParameter(models.Model):
     )
 
 
+class SupplierPartManager(models.Manager):
+    """ Define custom SupplierPart objects manager
+
+        The main purpose of this manager is to improve database hit as the
+        SupplierPart model involves A LOT of foreign keys lookups
+    """
+
+    def get_queryset(self):
+        # Always prefetch related models
+        return super().get_queryset().prefetch_related(
+            'part',
+            'supplier',
+            'manufacturer_part__manufacturer',
+        )
+
+
 class SupplierPart(models.Model):
     """ Represents a unique part as provided by a Supplier
     Each SupplierPart is identified by a SKU (Supplier Part Number)
@@ -450,6 +466,8 @@ class SupplierPart(models.Model):
         packaging: packaging that the part is supplied in, e.g. "Reel"
     """
 
+    objects = SupplierPartManager()
+
     @staticmethod
     def get_api_url():
         return reverse('api-supplier-part-list')

InvenTree/order/admin.py

@@ -15,6 +15,7 @@ from .models import SalesOrderAllocation
 
 class PurchaseOrderLineItemInlineAdmin(admin.StackedInline):
     model = PurchaseOrderLineItem
+    extra = 0
 
 
 class PurchaseOrderAdmin(ImportExportModelAdmin):