fix: clear "Retain Sample" and "Max Sample Quantity" in Item card if Has Batch No is uncheck (backport #30307) (#30314)

* fix: clear "Retain Sample" and "Max Sample Quantity" in Item card if Has Batch No is uncheck (#30307)

(cherry picked from commit ca8d757691)

# Conflicts:
#	erpnext/stock/doctype/item/test_item.py

* chore: conflicts

* refactor: correct usage for test decorator

Co-authored-by: HENRY Florian <florian.henry@open-concept.pro>
Co-authored-by: Ankush Menat <ankush@frappe.io>

erpnext/stock/doctype/item/item.py

@@ -108,6 +108,7 @@ class Item(Document):
 		self.validate_variant_attributes()
 		self.validate_variant_based_on_change()
 		self.validate_fixed_asset()
+		self.clear_retain_sample()
 		self.validate_retain_sample()
 		self.validate_uom_conversion_factor()
 		self.validate_customer_provided_part()
@@ -210,6 +211,13 @@ class Item(Document):
 			frappe.throw(_("{0} Retain Sample is based on batch, please check Has Batch No to retain sample of item").format(
 				self.item_code))
 
+	def clear_retain_sample(self):
+		if not self.has_batch_no:
+			self.retain_sample = None
+
+		if not self.retain_sample:
+			self.sample_quantity = None
+
 	def add_default_uom_in_conversion_factor_table(self):
 		if not self.is_new() and self.has_value_changed("stock_uom"):
 			self.uoms = []

erpnext/stock/doctype/item/test_item.py

@@ -622,6 +622,20 @@ class TestItem(FrappeTestCase):
 		item.item_group = "All Item Groups"
 		item.save()  # if item code saved without item_code then series worked
 
+	@change_settings("Stock Settings", {"sample_retention_warehouse": "_Test Warehouse - _TC"})
+	def test_retain_sample(self):
+		item = make_item("_TestRetainSample", {'has_batch_no': 1, 'retain_sample': 1, 'sample_quantity': 1})
+
+		self.assertEqual(item.has_batch_no, 1)
+		self.assertEqual(item.retain_sample, 1)
+		self.assertEqual(item.sample_quantity, 1)
+
+		item.has_batch_no = None
+		item.save()
+		self.assertEqual(item.retain_sample, None)
+		self.assertEqual(item.sample_quantity, None)
+		item.delete()
+
 
 def set_item_variant_settings(fields):
 	doc = frappe.get_doc('Item Variant Settings')