Add ability for Company model to count stock sourced from that supplier

InvenTree/company/models.py

@@ -7,6 +7,7 @@ from __future__ import unicode_literals
 
 import os
 
+from django.apps import apps
 from django.db import models
 from django.urls import reverse
 from django.conf import settings
@@ -111,6 +112,19 @@ class Company(models.Model):
         """ Return True if this company supplies any parts """
         return self.part_count > 0
 
+    @property
+    def stock_items(self):
+        """ Return a list of all stock items supplied by this company """
+        stock = apps.get_model('stock', 'StockItem')
+        return stock.objects.filter(supplier_part__supplier=self.id).all()
+
+    @property
+    def stock_count(self):
+        """ Return the number of stock items supplied by this company """
+        stock = apps.get_model('stock', 'StockItem')
+        return stock.objects.filter(supplier_part__supplier=self.id).count()
+
+
 
 class Contact(models.Model):
     """ A Contact represents a person who works at a particular company.