Merge branch 'develop' into fix-po-no-fetching
diff --git a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
index 4b59887..af6c696 100644
--- a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
@@ -1401,6 +1401,7 @@
 	def set_missing_values(source, target):
 		target.ignore_pricing_rule = 1
 		target.run_method("set_missing_values")
+		target.run_method("set_po_nos")
 		target.run_method("calculate_taxes_and_totals")
 
 	def update_item(source_doc, target_doc, source_parent):
diff --git a/erpnext/controllers/selling_controller.py b/erpnext/controllers/selling_controller.py
index 5886171..e5405b2 100644
--- a/erpnext/controllers/selling_controller.py
+++ b/erpnext/controllers/selling_controller.py
@@ -371,13 +371,29 @@
 		self.make_sl_entries(sl_entries)
 
 	def set_po_nos(self):
-		if self.doctype in ("Delivery Note", "Sales Invoice") and hasattr(self, "items"):
-			ref_fieldname = "against_sales_order" if self.doctype == "Delivery Note" else "sales_order"
-			sales_orders = list(set([d.get(ref_fieldname) for d in self.items if d.get(ref_fieldname)]))
-			if sales_orders:
-				po_nos = frappe.get_all('Sales Order', 'po_no', filters = {'name': ('in', sales_orders)})
-				if po_nos and po_nos[0].get('po_no'):
-					self.po_no = ', '.join(list(set([d.po_no for d in po_nos if d.po_no])))
+		if self.doctype == 'Sales Invoice' and hasattr(self, "items"):
+			self.set_pos_for_sales_invoice()
+		if self.doctype == 'Delivery Note' and hasattr(self, "items"):
+			self.set_pos_for_delivery_note()
+
+	def set_pos_for_sales_invoice(self):
+		po_nos = []
+		self.get_po_nos('Sales Order', 'sales_order', po_nos)
+		self.get_po_nos('Delivery Note', 'delivery_note', po_nos)
+		self.po_no = ', '.join(list(set(po_nos)))
+
+	def set_pos_for_delivery_note(self):
+		po_nos = []
+		self.get_po_nos('Sales Order', 'against_sales_order', po_nos)
+		self.get_po_nos('Sales Invoice', 'against_sales_invoice', po_nos)
+		self.po_no = ', '.join(list(set(po_nos)))
+
+	def get_po_nos(self, ref_doctype, ref_fieldname, po_nos):
+		doc_list = list(set([d.get(ref_fieldname) for d in self.items if d.get(ref_fieldname)]))
+		if doc_list:
+			po_no_list = frappe.get_all(ref_doctype, 'po_no', filters = {'name': ('in', doc_list)})
+			if po_no_list and po_no_list[0].get('po_no'):
+				po_nos += [d.po_no for d in po_no_list if d.po_no]
 
 	def set_gross_profit(self):
 		if self.doctype in ["Sales Order", "Quotation"]: