Create "SalesOrderAllocation" object

- Links multiple StockItem objects to a single SalesOrderLineItem

InvenTree/order/api.py

@@ -335,7 +335,7 @@ class SOLineItemList(generics.ListCreateAPIView):
         return queryset.prefetch_related(
             'part',
             'part__stock_items',
-            'stock_items',
+            'allocations',
             'order',
         )
 

InvenTree/order/migrations/0024_salesorderallocation.py

@@ -0,0 +1,26 @@
+# Generated by Django 3.0.5 on 2020-04-22 02:09
+
+import InvenTree.fields
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0030_auto_20200422_0015'),
+        ('order', '0023_auto_20200420_2309'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='SalesOrderAllocation',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('quantity', InvenTree.fields.RoundingDecimalField(decimal_places=5, default=1, max_digits=15, validators=[django.core.validators.MinValueValidator(0)])),
+                ('item', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='sales_order_allocation', to='stock.StockItem')),
+                ('line', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='allocations', to='order.SalesOrderLineItem')),
+            ],
+        ),
+    ]

InvenTree/order/models.py

@@ -380,6 +380,26 @@ class SalesOrderLineItem(OrderLineItem):
         This is a summation of the quantity of each attached StockItem
         """
 
-        query = self.stock_items.aggregate(allocated=Coalesce(Sum('quantity'), Decimal(0)))
+        query = self.allocations.aggregate(allocated=Coalesce(Sum('quantity'), Decimal(0)))
 
         return query['allocated']
+
+
+class SalesOrderAllocation(models.Model):
+    """
+    This model is used to 'allocate' stock items to a SalesOrder.
+    Items that are "allocated" to a SalesOrder are not yet "attached" to the order,
+    but they will be once the order is fulfilled.
+
+    Attributes:
+        line: SalesOrderLineItem reference
+        item: StockItem reference
+        quantity: Quantity to take from the StockItem
+
+    """
+
+    line = models.ForeignKey(SalesOrderLineItem, on_delete=models.CASCADE, related_name='allocations')
+
+    item = models.OneToOneField('stock.StockItem', on_delete=models.CASCADE, related_name='sales_order_allocation')
+
+    quantity = RoundingDecimalField(max_digits=15, decimal_places=5, validators=[MinValueValidator(0)], default=1)

InvenTree/order/tests.py

@@ -31,11 +31,11 @@ class OrderTest(TestCase):
 
         self.assertEqual(order.get_absolute_url(), '/order/purchase-order/1/')
 
-        self.assertEqual(str(order), 'PO 1')
+        self.assertEqual(str(order), 'PO 1 - ACME')
         
         line = PurchaseOrderLineItem.objects.get(pk=1)
 
-        self.assertEqual(str(line), "100 x ACME0001 from ACME (for PO 1)")
+        self.assertEqual(str(line), "100 x ACME0001 from ACME (for PO 1 - ACME)")
 
     def test_on_order(self):
         """ There should be 3 separate items on order for the M2x4 LPHS part """