Finally got migrations working together

InvenTree/part/models.py

@@ -11,7 +11,7 @@ from django.db.models.signals import pre_delete
 from django.dispatch import receiver
 
 from InvenTree.models import InvenTreeTree
-
+from company.models import Company
 
 class PartCategory(InvenTreeTree):
     """ PartCategory provides hierarchical organization of Part objects.
@@ -111,7 +111,7 @@ class Part(models.Model):
                                          related_name='default_parts')
 
     # Default supplier part
-    default_supplier = models.ForeignKey('company.SupplierPart',
+    default_supplier = models.ForeignKey('part.SupplierPart',
                                          on_delete=models.SET_NULL,
                                          blank=True, null=True,
                                          help_text='Default supplier part',
@@ -352,3 +352,78 @@ class BomItem(models.Model):
             par=self.part.name,
             child=self.sub_part.name,
             n=self.quantity)
+
+class SupplierPart(models.Model):
+    """ Represents a unique part as provided by a Supplier
+    Each SupplierPart is identified by a MPN (Manufacturer Part Number)
+    Each SupplierPart is also linked to a Part object
+    - A Part may be available from multiple suppliers
+    """
+
+    def get_absolute_url(self):
+        return "/supplier-part/{id}/".format(id=self.id)
+
+    class Meta:
+        unique_together = ('part', 'supplier', 'SKU')
+
+    # Link to an actual part
+# The part will have a field 'supplier_parts' which links to the supplier part options
+    part = models.ForeignKey(Part, on_delete=models.CASCADE,
+                             related_name='supplier_parts')
+
+    supplier = models.ForeignKey(Company, on_delete=models.CASCADE,
+                                 related_name='parts')
+
+    SKU = models.CharField(max_length=100, help_text='Supplier stock keeping unit')
+
+    manufacturer = models.CharField(max_length=100, blank=True, help_text='Manufacturer')
+
+    MPN = models.CharField(max_length=100, blank=True, help_text='Manufacturer part number')
+
+    URL = models.URLField(blank=True)
+
+    description = models.CharField(max_length=250, blank=True)
+
+    # Default price for a single unit
+    single_price = models.DecimalField(max_digits=10, decimal_places=3, default=0)
+
+    # Base charge added to order independent of quantity e.g. "Reeling Fee"
+    base_cost = models.DecimalField(max_digits=10, decimal_places=3, default=0)
+
+    # packaging that the part is supplied in, e.g. "Reel"
+    packaging = models.CharField(max_length=50, blank=True)
+
+    # multiple that the part is provided in
+    multiple = models.PositiveIntegerField(default=1, validators=[MinValueValidator(0)])
+
+    # Mimumum number required to order
+    minimum = models.PositiveIntegerField(default=1, validators=[MinValueValidator(0)])
+
+    # lead time for parts that cannot be delivered immediately
+    lead_time = models.DurationField(blank=True, null=True)
+
+    def __str__(self):
+        return "{sku} - {supplier}".format(
+            sku=self.SKU,
+            supplier=self.supplier.name)
+
+
+class SupplierPriceBreak(models.Model):
+    """ Represents a quantity price break for a SupplierPart
+    - Suppliers can offer discounts at larger quantities
+    - SupplierPart(s) may have zero-or-more associated SupplierPriceBreak(s)
+    """
+
+    part = models.ForeignKey(SupplierPart, on_delete=models.CASCADE, related_name='price_breaks')
+    quantity = models.PositiveIntegerField(validators=[MinValueValidator(0)])
+    cost = models.DecimalField(max_digits=10, decimal_places=3)
+
+    class Meta:
+        unique_together = ("part", "quantity")
+
+    def __str__(self):
+        return "{mpn} - {cost}{currency} @ {quan}".format(
+            mpn=self.part.MPN,
+            cost=self.cost,
+            currency=self.currency if self.currency else '',
+            quan=self.quantity)