From 3d9ad24e27621c97235a1a999092422ee0513c5b Mon Sep 17 00:00:00 2001
From: eeintech <eeintech@eeinte.ch>
Date: Tue, 13 Jul 2021 12:55:36 -0400
Subject: [PATCH] Defined custom SupplierPart object manager and prefetch
 related models in all queries

---
 InvenTree/company/api.py    |  6 +-----
 InvenTree/company/models.py | 18 ++++++++++++++++++
 InvenTree/order/admin.py    |  1 +
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/InvenTree/company/api.py b/InvenTree/company/api.py
index 2c05c98d91..76b08ec27e 100644
--- a/InvenTree/company/api.py
+++ b/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):
 
diff --git a/InvenTree/company/models.py b/InvenTree/company/models.py
index 3786531311..778e00cde1 100644
--- a/InvenTree/company/models.py
+++ b/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')
diff --git a/InvenTree/order/admin.py b/InvenTree/order/admin.py
index 1e7b20e5a1..5d843fc624 100644
--- a/InvenTree/order/admin.py
+++ b/InvenTree/order/admin.py
@@ -15,6 +15,7 @@ from .models import SalesOrderAllocation
 
 class PurchaseOrderLineItemInlineAdmin(admin.StackedInline):
     model = PurchaseOrderLineItem
+    extra = 0
 
 
 class PurchaseOrderAdmin(ImportExportModelAdmin):