Create "SalesOrderAllocation" object

- Links multiple StockItem objects to a single SalesOrderLineItem

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')),
+            ],
+        ),
+    ]