feat: Get invoiced item's gross margin using API

erpnext/accounts/report/gross_profit/gross_profit.js

@@ -23,6 +23,12 @@ frappe.query_reports["Gross Profit"] = {
 			"fieldtype": "Date",
 			"default": frappe.defaults.get_user_default("year_end_date")
 		},
+		{
+			"fieldname":"sales_invoice",
+			"label": __("Sales Invoice"),
+			"fieldtype": "Link",
+			"options": "Sales Invoice"
+		},
 		{
 			"fieldname":"group_by",
 			"label": __("Group By"),

erpnext/accounts/report/gross_profit/gross_profit.py

@@ -302,6 +302,12 @@ class GrossProfitGenerator(object):
 			sales_person_cols = ""
 			sales_team_table = ""
 
+		if self.filters.get("sales_invoice"):
+			conditions += " and `tabSales Invoice`.name = %(sales_invoice)s"
+
+		if self.filters.get("item_code"):
+			conditions += " and `tabSales Invoice Item`.item_code = %(item_code)s"
+
 		self.si_list = frappe.db.sql("""
 			select
 				`tabSales Invoice Item`.parenttype, `tabSales Invoice Item`.parent,

erpnext/accounts/report/utils.py

@@ -135,3 +135,22 @@ def get_appropriate_company(filters):
 		company = get_default_company()
 
 	return company
+
+@frappe.whitelist()
+def get_invoiced_item_gross_margin(sales_invoice=None, item_code=None, company=None):
+	from erpnext.accounts.report.gross_profit.gross_profit import GrossProfitGenerator
+
+	sales_invoice = sales_invoice or frappe.form_dict.get('sales_invoice')
+	item_code = item_code or frappe.form_dict.get('item_code')
+	company = company or frappe.get_cached_value("Sales Invoice", sales_invoice, 'company')
+
+	filters = {
+		'sales_invoice': sales_invoice,
+		'item_code': item_code,
+		'company': company,
+		'group_by': 'Invoice'
+	}
+
+	gross_profit_data = GrossProfitGenerator(filters)
+
+	return gross_profit_data.grouped_data