add validation in faq and discount page

lib/pages/discount/discount_editor.dart

@@ -30,6 +30,7 @@ class _DiscountEditorState extends State<DiscountEditor> {
   bool _isNew = false;
   String customerName = '';
   String customerId = '';
+  final _discountFormKey = GlobalKey<FormState>();
 
   @override
   void initState() {
@@ -51,12 +52,28 @@ class _DiscountEditorState extends State<DiscountEditor> {
     final codeBox = InputText(
       labelTextKey: 'discount.code',
       iconData: FontAwesomeIcons.algolia,
-        controller: _codeController);
+      controller: _codeController,
+      autovalidateMode: AutovalidateMode.onUserInteraction,
+      validator: (value) {
+        if (value == null || value.isEmpty) {
+          return "Please insert code";
+        }
+        return null;
+      },
+    );
 
     final amountBox = InputText(
       labelTextKey: 'discount.amount',
       iconData: FontAwesomeIcons.moneyBill,
-        controller: _amountController);
+      controller: _amountController,
+      autovalidateMode: AutovalidateMode.onUserInteraction,
+      validator: (value) {
+        if (value == null || value.isEmpty) {
+          return "Please insert amount";
+        }
+        return null;
+      },
+    );
 
     final statusBox = DisplayText(
       text: _statusController.text,
@@ -100,7 +117,9 @@ class _DiscountEditorState extends State<DiscountEditor> {
                       onPressed: _delete)
             ],
           ),
-          body: Padding(
+          body: Form(
+            key: _discountFormKey,
+            child: Padding(
               padding: const EdgeInsets.all(8.0),
               child: Column(
                 children: <Widget>[
@@ -128,11 +147,15 @@ class _DiscountEditorState extends State<DiscountEditor> {
                   )
                 ],
               ),
+            ),
           )),
     );
   }
 
   _save() async {
+    if (!_discountFormKey.currentState!.validate()) {
+      return null;
+    }
     setState(() {
       _isLoading = true;
     });

lib/pages/faq/faq_edit_page.dart

@@ -29,7 +29,7 @@ class _FAQEditorState extends State<FAQEditor> {
   TextEditingController _pageLabelEng = new TextEditingController();
   TextEditingController _pageLabelMm = new TextEditingController();
 
-  final _formKey = GlobalKey<FormState>();
+  final _faqFormKey = GlobalKey<FormState>();
   bool _isLoading = false;
   bool _isNew = false;
   String _pageLink = info;
@@ -57,9 +57,16 @@ class _FAQEditorState extends State<FAQEditor> {
     final snBox = InputText(
       controller: _sn,
       labelTextKey: "faq.edit.sn",
-      maxLines: 1,
       withBorder: false,
       textInputType: TextInputType.number,
+      autovalidateMode: AutovalidateMode.onUserInteraction,
+      validator: (value) {
+        if (value == null || value.isEmpty || value.length==0) {
+          return "Please insert S/N";
+        }
+
+        return null;
+      },
     );
 
     final questionEngBox = InputText(
@@ -151,7 +158,7 @@ class _FAQEditorState extends State<FAQEditor> {
               ],
             ),
             body: Form(
-              key: _formKey,
+              key: _faqFormKey,
               child: Padding(
                 padding: EdgeInsets.only(left: 24.0, right: 24.0),
                 child: ListView(
@@ -189,6 +196,10 @@ class _FAQEditorState extends State<FAQEditor> {
   }
 
   _save() async {
+    if (!_faqFormKey.currentState!.validate()) {
+      return null;
+    }
+
     setState(() {
       _isLoading = true;
     });
@@ -212,7 +223,7 @@ class _FAQEditorState extends State<FAQEditor> {
       }
       Navigator.pop(context);
     } catch (e) {
-      showMsgDialog(context, "Error", e.toString());
+      showMsgDialog(context, "Error", "Invalid S/N");
     } finally {
       setState(() {
         _isLoading = false;