Create initial models for 'Order'

- PurchaseOrder
- PurchaseOrderLineItem

(These are based on some abstract model classes)

InvenTree/order/migrations/0001_initial.py

@@ -0,0 +1,48 @@
+# Generated by Django 2.2 on 2019-06-04 12:17
+
+from django.conf import settings
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('company', '0005_auto_20190525_2356'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PurchaseOrder',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('reference', models.CharField(help_text='Order reference', max_length=64, unique=True)),
+                ('description', models.CharField(help_text='Order description', max_length=250)),
+                ('creation_date', models.DateField(auto_now=True)),
+                ('issue_date', models.DateField(blank=True, null=True)),
+                ('notes', models.TextField(blank=True, help_text='Order notes')),
+                ('created_by', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to=settings.AUTH_USER_MODEL)),
+                ('supplier', models.ForeignKey(help_text='Company', on_delete=django.db.models.deletion.CASCADE, related_name='Orders', to='company.Company')),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+        migrations.CreateModel(
+            name='PurchaseOrderLineItem',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('quantity', models.PositiveIntegerField(default=1, help_text='Item quantity', validators=[django.core.validators.MinValueValidator(0)])),
+                ('reference', models.CharField(blank=True, help_text='Line item reference', max_length=100)),
+                ('received', models.PositiveIntegerField(default=0, help_text='Number of items received')),
+                ('order', models.ForeignKey(help_text='Purchase Order', on_delete=django.db.models.deletion.CASCADE, related_name='lines', to='order.PurchaseOrder')),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+    ]