fix: Minor changes

Added value in fetch from and removed client side code
diff --git a/erpnext/accounts/doctype/discounted_invoice/discounted_invoice.json b/erpnext/accounts/doctype/discounted_invoice/discounted_invoice.json
index 9a276ca..5c3519a 100644
--- a/erpnext/accounts/doctype/discounted_invoice/discounted_invoice.json
+++ b/erpnext/accounts/doctype/discounted_invoice/discounted_invoice.json
@@ -38,6 +38,8 @@
    "read_only": 1
   },
   {
+   "fetch_from": "sales_invoice.outstanding_amount",
+   "fetch_if_empty": 1,
    "fieldname": "outstanding_amount",
    "fieldtype": "Currency",
    "in_list_view": 1,
@@ -58,7 +60,7 @@
   }
  ],
  "istable": 1,
- "modified": "2019-09-23 15:29:54.199318",
+ "modified": "2019-09-26 11:05:36.016772",
  "modified_by": "Administrator",
  "module": "Accounts",
  "name": "Discounted Invoice",
diff --git a/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.js b/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.js
index c061fb7..f928f11 100644
--- a/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.js
+++ b/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.js
@@ -204,15 +204,9 @@
 });
 
 frappe.ui.form.on('Discounted Invoice', {
-	sales_invoice: (frm, cdt, cdn) => {
+	sales_invoice: (frm) => {
 		frm.events.calculate_total_amount(frm);
 		frm.events.refresh_filters(frm);	
-		
-		let row = locals[cdt][cdn];
-		frappe.db.get_value("Sales Invoice",row["sales_invoice"], "outstanding_amount", (res) => {
-			row.outstanding_amount = res["outstanding_amount"];
-			frm.refresh_field("invoices");
-		});
 	},
 	invoices_remove: (frm) => {
 		frm.events.calculate_total_amount(frm);