Part units (#4854)

* Add validation to part units field

* Add "pack_units" field to the SupplierPart model

* Migrate old units to new units, and remove old field

* Table fix

* Fixture fix

* Update migration

* Improve "hook" for loading custom unit database

* Display part units column in part table

- Also allow ordering by part units
- Allow filtering to show parts which have defined units

* Adds data migration for converting units to valid values

* Add "pack_units_native" field to company.SupplierPart model

* Clean pack units when saving a SupplierPart

- Convert to native part units
- Handle empty units value
- Add unit tests

* Add background function to rebuild supplier parts when a part is saved

- Required to ensure that the "pack_size_native" is up to date

* Template updates

* Sort by native units first

* Bump API version

* Rename "pack_units" to "pack_quantity"

* Update migration file

- Allow reverse migration

* Fix for currency migration

- Handle case where no currencies are provided
- Handle case where base currency is not in provided options

* Adds unit test for data migration

* Add unit test for part.units data migration

- Check that units fields are updated correctly

* Add some extra "default units"

- each / piece
- dozen / hundred / thousand
- Add unit testing also

* Update references to "pack_size"

- Replace with "pack_quantity" or "pack_quantity_native" as appropriate

* Improvements based on unit testing

* catch error

* Docs updates

* Fixes for pricing tests

* Update unit tests for part migrations · 1b6b6d9d

* Bug fix for conversion code

* javascript updates

* JS formatting fix

InvenTree/stock/migrations/0094_auto_20230220_0025.py

@@ -2,6 +2,7 @@
 
 import logging
 
+from django.core.exceptions import FieldError
 from django.db import migrations
 
 logger = logging.getLogger('inventree')
@@ -38,10 +39,13 @@ def fix_purchase_price(apps, schema_editor):
         supplier_part=None
     ).exclude(
         purchase_price=None
-    ).exclude(
-        supplier_part__pack_size=1
     )
 
+    try:
+        items = items.exclude(supplier_part__pack_size=1)
+    except FieldError:
+        pass
+
     n_updated = 0
 
     for item in items: