fix: rename variant item_code/item_name when attribute abbreviation changes

Item Attribute abbreviations only got baked into a variant's item_code
and item_name at creation time (make_variant_item_code returns early
once item_code is set). Renaming an abbreviation afterwards left every
existing variant stuck with the stale code, silently out of sync with
its own attribute.

Detect abbreviation renames on Item Attribute save, find every variant
using the affected value, and rebuild+rename its item_code via
frappe.rename_doc so linked records follow along. item_name is rebuilt
in lockstep from the template's item_name, even if it had since been
customized, since both fields are meant to be derived from the same
abbreviation.

(cherry picked from commit c0cfe5f363)

erpnext/controllers/item_variant.py

@@ -177,6 +177,68 @@ def update_variant_attribute_values(item_attribute):
 	frappe.flags.attribute_values = None
 
 
+def get_attribute_abbr_renames(item_attribute):
+	"""Return the set of (current) attribute values whose abbreviation was renamed."""
+	if item_attribute.numeric_values:
+		return set()
+
+	db_value = item_attribute.get_doc_before_save()
+	if not db_value:
+		return set()
+
+	old_abbrs = {d.name: d.abbr for d in db_value.item_attribute_values}
+	changed_values = set()
+
+	for row in item_attribute.item_attribute_values:
+		if row.name in old_abbrs and old_abbrs[row.name] != row.abbr:
+			changed_values.add(row.attribute_value)
+
+	return changed_values
+
+
+def update_variant_item_codes_for_abbr_renames(item_attribute):
+	"""Rebuild item_code/item_name of variant Items affected by a renamed Item Attribute abbreviation."""
+	changed_values = get_attribute_abbr_renames(item_attribute)
+	if not changed_values:
+		return
+
+	item_variant_table = frappe.qb.DocType("Item Variant Attribute")
+	variant_names = (
+		frappe.qb.from_(item_variant_table)
+		.select(item_variant_table.parent)
+		.where(item_variant_table.attribute == item_attribute.name)
+		.where(item_variant_table.attribute_value.isin(list(changed_values)))
+		.distinct()
+		.run(pluck=True)
+	)
+
+	for variant_name in variant_names:
+		rename_variant_item_code(variant_name)
+
+
+def rename_variant_item_code(variant_name):
+	"""Recompute a variant's item_code/item_name from its template and current attribute abbreviations,
+	renaming the Item if it has changed."""
+	variant = frappe.get_doc("Item", variant_name)
+	if not variant.variant_of:
+		return
+
+	template = frappe.get_cached_doc("Item", variant.variant_of)
+
+	new_code = frappe._dict({"item_code": None, "item_name": None, "attributes": variant.attributes})
+	make_variant_item_code(template.item_code, template.item_name, new_code)
+
+	if not new_code.item_code or new_code.item_code == variant.item_code:
+		return
+
+	frappe.rename_doc("Item", variant.item_code, new_code.item_code)
+
+	# Keep item_name in lockstep with item_code: both are derived from the same abbreviation, so
+	# item_name is always rebuilt here too, even if it had since been customized away from that pattern.
+	if new_code.item_name and new_code.item_name != variant.item_name:
+		frappe.db.set_value("Item", new_code.item_code, "item_name", new_code.item_name)
+
+
 def validate_item_attribute_value(attributes_list, attribute, attribute_value, item, from_variant=True):
 	allow_rename_attribute_value = frappe.db.get_single_value(
 		"Item Variant Settings", "allow_rename_attribute_value"

erpnext/stock/doctype/item_attribute/item_attribute.py

@@ -10,6 +10,7 @@ from frappe.utils import flt
 from erpnext.controllers.item_variant import (
 	InvalidItemAttributeValueError,
 	update_variant_attribute_values,
+	update_variant_item_codes_for_abbr_renames,
 	validate_is_incremental,
 	validate_item_attribute_value,
 )
@@ -49,6 +50,7 @@ class ItemAttribute(Document):
 
 	def on_update(self):
 		update_variant_attribute_values(self)
+		update_variant_item_codes_for_abbr_renames(self)
 		self.validate_exising_items()
 		self.set_enabled_disabled_in_items()