Update data migration file (#4596)

* Update data migration file

- Do not call "save()" on the ORM model as it has some other hooks
- Manually calculate checksum to determine which line items are "valid"
- Update BomItem checksum calculation

* Update BomItem hashing function

- Ensure it remains the same after saving
- Must use normalize(quantity) otherwise weird issues

InvenTree/part/models.py

@@ -3631,32 +3631,32 @@ class BomItem(DataImportMixin, MetadataMixin, models.Model):
         """Calculate the checksum hash of this BOM line item.
 
         The hash is calculated from the following fields:
-        - Part.full_name (if the part name changes, the BOM checksum is invalidated)
-        - Quantity
-        - Reference field
-        - Note field
-        - Optional field
-        - Inherited field
+        - part.pk
+        - sub_part.pk
+        - quantity
+        - reference
+        - optional
+        - inherited
+        - consumable
+        - allow_variants
         """
         # Seed the hash with the ID of this BOM item
-        result_hash = hashlib.md5(str(self.id).encode())
+        result_hash = hashlib.md5(''.encode())
 
-        # Update the hash based on line information
-        result_hash.update(str(self.sub_part.id).encode())
-        result_hash.update(str(self.sub_part.full_name).encode())
-        result_hash.update(str(self.quantity).encode())
-        result_hash.update(str(self.note).encode())
-        result_hash.update(str(self.reference).encode())
-        result_hash.update(str(self.optional).encode())
-        result_hash.update(str(self.inherited).encode())
+        # The following components are used to calculate the checksum
+        components = [
+            self.part.pk,
+            self.sub_part.pk,
+            normalize(self.quantity),
+            self.reference,
+            self.optional,
+            self.inherited,
+            self.consumable,
+            self.allow_variants
+        ]
 
-        # Optionally encoded for backwards compatibility
-        if self.consumable:
-            result_hash.update(str(self.consumable).encode())
-
-        # Optionally encoded for backwards compatibility
-        if self.allow_variants:
-            result_hash.update(str(self.allow_variants).encode())
+        for component in components:
+            result_hash.update(str(component).encode())
 
         return str(result_hash.digest())
 
@@ -3667,7 +3667,7 @@ class BomItem(DataImportMixin, MetadataMixin, models.Model):
             valid: If true, validate the hash, otherwise invalidate it (default = True)
         """
         if valid:
-            self.checksum = str(self.get_item_hash())
+            self.checksum = self.get_item_hash()
         else:
             self.checksum = ''