add update message

lib/constants.dart

@@ -22,3 +22,20 @@ const String dataLink =
     "https://raw.githubusercontent.com/kphanipavan/IIITB_Menu/menu_scraper/out.json";
 
 enum DataStatus { Loaded, Loading, NotFound }
+
+Widget newNoMenuWidget = Center(
+  child: Column(children: [
+    const Text("Menu not available for this session",
+        style: TextStyle(fontSize: 20, fontStyle: FontStyle.italic)),
+    RichText(
+      text: const TextSpan(
+        children: [
+          TextSpan(text: "Click "),
+          WidgetSpan(child: Icon(Icons.update_rounded)),
+          TextSpan(text: " to check for updates.")
+        ],
+        style: TextStyle(fontSize: 20, fontStyle: FontStyle.italic),
+      ),
+    )
+  ], mainAxisAlignment: MainAxisAlignment.center),
+);

lib/models/globalModel.dart

@@ -29,6 +29,8 @@ class GlobalModel extends ChangeNotifier {
   }
 
   updateCall() async {
+    this.menuAvailable = DataStatus.Loading;
+    notifyListeners();
     this.mainData = await GlobalModel.updateLocal();
     if (this.mainData["dates"].keys.contains(this.date)) {
       this.menuAvailable = DataStatus.Loaded;

lib/views/homePage.dart

@@ -148,10 +148,10 @@ class HomePage extends StatelessWidget {
                           MenuListView(menuType: "dn"),
                         ]
                       : [
-                          noMenuWidget,
-                          noMenuWidget,
-                          noMenuWidget,
-                          noMenuWidget,
+                          newNoMenuWidget,
+                          newNoMenuWidget,
+                          newNoMenuWidget,
+                          newNoMenuWidget,
                         ]),
             );
           });