Add table for price breaks for selling a part

InvenTree/part/migrations/0049_partsellpricebreak.py

@@ -0,0 +1,30 @@
+# Generated by Django 3.0.7 on 2020-09-17 13:22
+
+import InvenTree.fields
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('common', '0007_colortheme'),
+        ('part', '0048_auto_20200902_1404'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PartSellPriceBreak',
+            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(1)])),
+                ('cost', InvenTree.fields.RoundingDecimalField(decimal_places=5, max_digits=10, validators=[django.core.validators.MinValueValidator(0)])),
+                ('currency', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='common.Currency')),
+                ('part', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='salepricebreaks', to='part.Part')),
+            ],
+            options={
+                'unique_together': {('part', 'quantity')},
+            },
+        ),
+    ]