From bf9744e145f6a0a1724653018b37445e4172a3f4 Mon Sep 17 00:00:00 2001
From: Mihir Kandoi <kandoimihir@gmail.com>
Date: Mon, 10 Aug 2026 13:25:20 +0530
Subject: [PATCH] fix(manufacturing): correct nested BOM quantities

---
 .../report/bom_explorer/bom_explorer.py       | 16 +++++-
 .../report/bom_explorer/test_bom_explorer.py  | 54 ++++++++++++++++++-
 2 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/erpnext/manufacturing/report/bom_explorer/bom_explorer.py b/erpnext/manufacturing/report/bom_explorer/bom_explorer.py
index 1f82ec847b3..426a74d90f9 100644
--- a/erpnext/manufacturing/report/bom_explorer/bom_explorer.py
+++ b/erpnext/manufacturing/report/bom_explorer/bom_explorer.py
@@ -25,10 +25,12 @@ def fetch_exploded_bom_items(root_bom):
 	recursive CTE -- replaces a query-per-node walk with a single query. UNION keeps it cycle-safe
 	and fetches each sub-BOM's items only once even when it is reused across the tree."""
 	bom_item = frappe.qb.DocType("BOM Item")
+	child_bom = frappe.qb.DocType("BOM").as_("child_bom")
 	tree = frappe.qb.Table("exploded_bom")
 	fields = [
 		bom_item.parent,
 		bom_item.qty,
+		bom_item.stock_qty,
 		bom_item.bom_no,
 		bom_item.item_code,
 		bom_item.item_name,
@@ -46,7 +48,11 @@ def fetch_exploded_bom_items(root_bom):
 		.where(tree.bom_no != "")
 	)
 	rows = (
-		frappe.qb.with_(seed + recursion, "exploded_bom", recursive=True).from_(tree).select(tree.star)
+		frappe.qb.with_(seed + recursion, "exploded_bom", recursive=True)
+		.from_(tree)
+		.left_join(child_bom)
+		.on(tree.bom_no == child_bom.name)
+		.select(tree.star, child_bom.quantity.as_("child_bom_qty"))
 	).run(as_dict=True)
 
 	children_map = defaultdict(list)
@@ -71,7 +77,13 @@ def build_exploded_rows(bom, children_map, data, indent=0, qty=1):
 			}
 		)
 		if item.bom_no:
-			build_exploded_rows(item.bom_no, children_map, data, indent + 1, item.qty)
+			build_exploded_rows(
+				item.bom_no,
+				children_map,
+				data,
+				indent + 1,
+				qty * item.stock_qty / item.child_bom_qty,
+			)
 
 
 def get_columns():
diff --git a/erpnext/manufacturing/report/bom_explorer/test_bom_explorer.py b/erpnext/manufacturing/report/bom_explorer/test_bom_explorer.py
index 54bfae2d6c2..b24467d069e 100644
--- a/erpnext/manufacturing/report/bom_explorer/test_bom_explorer.py
+++ b/erpnext/manufacturing/report/bom_explorer/test_bom_explorer.py
@@ -4,7 +4,7 @@
 import frappe
 
 from erpnext.manufacturing.doctype.bom.test_bom import create_nested_bom
-from erpnext.manufacturing.report.bom_explorer.bom_explorer import execute
+from erpnext.manufacturing.report.bom_explorer.bom_explorer import build_exploded_rows, execute
 from erpnext.tests.utils import ERPNextTestSuite
 
 
@@ -78,3 +78,55 @@ class TestBOMExplorer(ERPNextTestSuite):
 		# The leaf belongs to the sub-assembly, so it is exploded one level deeper.
 		self.assertEqual(rows_by_item[leaf_item]["indent"], 1)
 		self.assertEqual(rows_by_item[leaf_item]["bom_level"], 1)
+
+	def test_nested_bom_uses_stock_qty_for_output_normalization(self):
+		parent_bom = create_nested_bom(
+			{"parent": {"sub": {"leaf": {}}}},
+			prefix="_Test explorer converted quantity ",
+		)
+		sub_bom = frappe.get_doc("BOM", parent_bom.items[0].bom_no)
+
+		# The parent needs two boxes (20 units). The child BOM produces five units per batch.
+		frappe.db.set_value("BOM", sub_bom.name, "quantity", 5)
+		frappe.db.set_value("BOM Item", sub_bom.items[0].name, {"qty": 3, "stock_qty": 3})
+		frappe.db.set_value(
+			"BOM Item",
+			parent_bom.items[0].name,
+			{"qty": 2, "uom": "Box", "conversion_factor": 10, "stock_qty": 20},
+		)
+
+		data = self.run_report(parent_bom.name)
+		rows_by_item = {row["item_code"]: row for row in data}
+
+		self.assertEqual(rows_by_item["_Test explorer converted quantity sub"]["qty"], 2)
+		self.assertEqual(rows_by_item["_Test explorer converted quantity leaf"]["qty"], 12)
+
+	def test_nested_bom_multiplies_qty_at_every_level(self):
+		children_map = {
+			"root": [
+				frappe._dict(
+					item_code="parent",
+					idx=1,
+					bom_no="parent-bom",
+					child_bom_qty=1,
+					qty=8,
+					stock_qty=8,
+				)
+			],
+			"parent-bom": [
+				frappe._dict(
+					item_code="child",
+					idx=1,
+					bom_no="child-bom",
+					child_bom_qty=1,
+					qty=4,
+					stock_qty=4,
+				)
+			],
+			"child-bom": [frappe._dict(item_code="raw-material", idx=1, bom_no="", qty=2, stock_qty=2)],
+		}
+		data = []
+
+		build_exploded_rows("root", children_map, data)
+
+		self.assertEqual([row["qty"] for row in data], [8, 32, 64])