feat: link purchase invoice item with purchase order

erpnext/accounts/doctype/purchase_invoice/purchase_invoice.js

@@ -129,6 +129,26 @@ erpnext.accounts.PurchaseInvoice = class PurchaseInvoice extends erpnext.buying.
 			);
 		}
 
+		if (doc.docstatus === 0) {
+			const cur_doc = this.frm.doc;
+			const invoice_items = cur_doc.items;
+
+			this.frm.add_custom_button(__("Link to Purchase Order"), function () {
+				let unmapped_items = get_unmapped_items(invoice_items);
+
+				frappe.call({
+					method: "erpnext.accounts.doctype.purchase_invoice.purchase_invoice.link_purchase_order",
+					args: {
+						pi_item_code: unmapped_items,
+						supplier: cur_doc.supplier,
+					},
+					callback: function (r) {
+						assign_purchase_order(invoice_items, r.message, cur_doc);
+					},
+				});
+			});
+		}
+
 		if (doc.docstatus === 0) {
 			this.frm.add_custom_button(
 				__("Purchase Order"),
@@ -446,6 +466,51 @@ erpnext.accounts.PurchaseInvoice = class PurchaseInvoice extends erpnext.buying.
 	}
 };
 
+function get_unmapped_items(invoice_items) {
+	return invoice_items.map((item) => {
+		item.purchase_order = "";
+		return item.item_code;
+	});
+}
+
+function assign_purchase_order(invoice_items, items_to_link, cur_doc) {
+	if (!Object.keys(items_to_link).length) {
+		frappe.msgprint(__("No Purchase Orders matched"));
+		return;
+	}
+
+	let total_idx = invoice_items.length;
+
+	invoice_items.forEach((item) => {
+		const matched_item = items_to_link[item.item_code];
+		if (!matched_item) return;
+
+		if (item.qty > matched_item.qty) {
+			const new_row = frappe.model.add_child(cur_doc, item.doctype, "items");
+			Object.assign(new_row, item);
+			new_row.qty = item.qty - matched_item.qty;
+			new_row.idx = ++total_idx;
+
+			frappe.msgprint("Splitting " + new_row.qty + " units of " + new_row.item_code);
+			item.qty = matched_item.qty;
+		}
+
+		frappe.msgprint(
+			"Assigning " + matched_item.purchase_order + " to " + item.item_code + " (row " + item.idx + ")"
+		);
+		item.purchase_order = matched_item.purchase_order;
+
+		if (items_to_link[item.item_code]) {
+			items_to_link[item.item_code] -= item.qty;
+
+			if (items_to_link[item.item_code] <= 0) {
+				delete items_to_link[item.item_code];
+			}
+		}
+	});
+	refresh_field("items");
+}
+
 cur_frm.script_manager.make(erpnext.accounts.PurchaseInvoice);
 
 // Hide Fields

erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py

@@ -1,10 +1,11 @@
 # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
 # License: GNU General Public License v3. See license.txt
-
+import json
 
 import frappe
 from frappe import _, qb, throw
-from frappe.model.mapper import get_mapped_doc
+from frappe.model import child_table_fields, default_fields, table_fields
+from frappe.model.mapper import get_mapped_doc, map_fetch_fields, map_fields
 from frappe.query_builder.functions import Sum
 from frappe.utils import cint, cstr, flt, formatdate, get_link_to_form, getdate, nowdate
 
@@ -1934,6 +1935,31 @@ def make_stock_entry(source_name, target_doc=None):
 	return doc
 
 
+@frappe.whitelist()
+def link_purchase_order(pi_item_code, supplier):
+	pi_item_code = json.loads(pi_item_code)
+
+	purchase_orders = frappe.get_all(
+		"Purchase Order",
+		filters={"supplier": supplier, "docstatus": 1},
+		pluck="name",
+		order_by="creation asc",
+	)
+	purchase_order_items = frappe.get_all(
+		"Purchase Order Item",
+		filters={"parent": ["in", purchase_orders]},
+		fields=["parent", "item_code", "qty"],
+	)
+
+	item_to_po_map = {
+		item.item_code: {"purchase_order": item.parent, "qty": item.qty}
+		for item in purchase_order_items
+		if item.item_code in pi_item_code
+	}
+
+	return item_to_po_map
+
+
 @frappe.whitelist()
 def change_release_date(name, release_date=None):
 	if frappe.db.exists("Purchase Invoice", name):