From 7dd7b68ed6df0909bbcf050964f8df20ed51a785 Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Tue, 7 May 2019 23:03:05 +1000
Subject: [PATCH] Improve functions

---
 InvenTree/build/models.py | 19 +++++++++++--------
 InvenTree/build/views.py  |  7 ++++++-
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/InvenTree/build/models.py b/InvenTree/build/models.py
index 2a998dc26e..64cf8105c4 100644
--- a/InvenTree/build/models.py
+++ b/InvenTree/build/models.py
@@ -221,6 +221,16 @@ class Build(models.Model):
         self.status = self.COMPLETE
         self.save()
 
+    def getRequiredQuantity(self, part):
+        """ Calculate the quantity of <part> required to make this build.
+        """
+
+        try:
+            item = BomItem.objects.get(part=self.part.id, sub_part=part.id)
+            return item.quantity * self.quantity
+        except BomItem.DoesNotExist:
+            return 0
+
     def getAllocatedQuantity(self, part):
         """ Calculate the total number of <part> currently allocated to this build
         """
@@ -244,14 +254,7 @@ class Build(models.Model):
             The remaining allocated quantity
         """
 
-        try:
-            bom_item = BomItem.objects.get(part=self.part.id, sub_part=part.id)
-        except BomItem.DoesNotExist:
-            return 0
-
-        quantity = bom_item.quantity * self.quantity
-
-        return quantity - self.getAllocatedQuantity(part)
+        return max(self.getRequiredQuantity(part) - self.getAllocatedQuantity(part), 0)
 
     @property
     def required_parts(self):
diff --git a/InvenTree/build/views.py b/InvenTree/build/views.py
index cccd705e43..19af4b6458 100644
--- a/InvenTree/build/views.py
+++ b/InvenTree/build/views.py
@@ -294,6 +294,10 @@ class BuildItemCreate(AjaxCreateView):
                 # If there is only one item selected, select it
                 if len(stocks) == 1:
                     form.fields['stock_item'].initial = stocks[0].id
+                # There is no stock available
+                elif len(stocks) == 0:
+                    # TODO - Add a message to the form describing the problem
+                    pass
 
             except Part.DoesNotExist:
                 pass
@@ -324,7 +328,8 @@ class BuildItemCreate(AjaxCreateView):
 
                 # Try to work out how many parts to allocate
                 if part:
-                    initials['quantity'] = build.getUnallocatedQuantity(part)
+                    unallocated = build.getUnallocatedQuantity(part)
+                    initials['quantity'] = unallocated
 
             except Build.DoesNotExist:
                 pass