fix: Disallow negative rates in Purchase invoice (backport #54254) (#54393)

fix: Disallow negative rates in Purchase invoice (#54254)

(cherry picked from commit 23768ae)

Co-authored-by: Nishka Gosalia <58264710+nishkagosalia@users.noreply.github.com>

Author: mergify[bot]

erpnext/buying/doctype/buying_settings/buying_settings.json

@@ -24,6 +24,7 @@
   "allow_zero_qty_in_supplier_quotation",
   "use_transaction_date_exchange_rate",
   "allow_zero_qty_in_request_for_quotation",
+  "allow_negative_rates_for_items",
   "column_break_12",
   "maintain_same_rate",
   "allow_multiple_items",
@@ -279,6 +280,12 @@
    "fieldname": "validate_consumed_qty",
    "fieldtype": "Check",
    "label": "Validate Consumed Qty (as per BOM)"
+  },
+  {
+   "default": "0",
+   "fieldname": "allow_negative_rates_for_items",
+   "fieldtype": "Check",
+   "label": "Allow Negative rates for Items"
   }
  ],
  "grid_page_length": 50,
@@ -288,7 +295,7 @@
  "index_web_pages_for_search": 1,
  "issingle": 1,
  "links": [],
- "modified": "2026-03-16 13:28:19.432589",
+ "modified": "2026-04-15 16:07:35.484787",
  "modified_by": "Administrator",
  "module": "Buying",
  "name": "Buying Settings",

erpnext/buying/doctype/buying_settings/buying_settings.py

@@ -18,6 +18,7 @@ class BuyingSettings(Document):
 		from frappe.types import DF
 
 		allow_multiple_items: DF.Check
+		allow_negative_rates_for_items: DF.Check
 		allow_zero_qty_in_purchase_order: DF.Check
 		allow_zero_qty_in_request_for_quotation: DF.Check
 		allow_zero_qty_in_supplier_quotation: DF.Check

erpnext/controllers/status_updater.py

@@ -272,6 +272,12 @@ def validate_qty(self):
 				continue
 
 			items_to_validate = []
+			selling_negative_rate_allowed = frappe.get_single_value(
+				"Selling Settings", "allow_negative_rates_for_items"
+			)
+			buying_negative_rate_allowed = frappe.get_single_value(
+				"Buying Settings", "allow_negative_rates_for_items"
+			)
 
 			# get unique transactions to update
 			for d in self.get_all_children():
@@ -281,15 +287,24 @@ def validate_qty(self):
 				if hasattr(d, "qty") and d.qty > 0 and self.get("is_return"):
 					frappe.throw(_("For an item {0}, quantity must be negative number").format(d.item_code))
 
-				if not frappe.get_single_value("Selling Settings", "allow_negative_rates_for_items"):
+				if (
+					not selling_negative_rate_allowed and self.doctype in ["Sales Invoice", "Delivery Note"]
+				) or (
+					not buying_negative_rate_allowed
+					and self.doctype in ["Purchase Invoice", "Purchase Receipt"]
+				):
 					if hasattr(d, "item_code") and hasattr(d, "rate") and flt(d.rate) < 0:
 						frappe.throw(
 							_(
 								"For item {0}, rate must be a positive number. To Allow negative rates, enable {1} in {2}"
 							).format(
 								frappe.bold(d.item_code),
 								frappe.bold(_("`Allow Negative rates for Items`")),
-								get_link_to_form("Selling Settings", "Selling Settings"),
+								get_link_to_form(
+									"Selling Settings"
+									if self.doctype in ["Sales Invoice", "Delivery Note"]
+									else "Buying Settings"
+								),
 							),
 						)