feat: book list loading

lib/src/providers/book_provider.dart

@@ -12,8 +12,15 @@ class BookProvider with ChangeNotifier {
   String? searchKeyword;
   String? filterByCategory;
 
+  bool isLoading = false;
+
+  void setLoading(bool value) {
+    isLoading = value;
+  }
+
   Future<void> getBooks() async {
     try {
+      setLoading(true);
       String url = '$baseUrl/books';
       if (filterByCategory != null) {
         url += '?category__name=$filterByCategory';
@@ -34,6 +41,7 @@ class BookProvider with ChangeNotifier {
         debugPrint("Error: Fetch books failed, $code");
       }
 
+      setLoading(false);
       notifyListeners();
     } catch (error) {
       debugPrint("Error: Fetch books failed, $error");

lib/src/widgets/books/book_list.dart

@@ -25,7 +25,7 @@ class _BookList extends State<BookList> {
   Widget build(BuildContext context) {
     return Consumer<BookProvider>(
       builder: (context, bookProvider, child) {
-        if (bookProvider.books != null) {
+        if (!bookProvider.isLoading) {
           final Iterable<Book> books = bookProvider.books!.map((book) {
             if (book["category_detail"] != null) {
               final Category category = Category.fromJson(

lib/src/widgets/forms/search_form.dart

@@ -27,10 +27,15 @@ class _SearchForm extends State<SearchForm> {
         hintText: "Enter keywords...",
         elevation: WidgetStateProperty.all(0),
         onChanged: (value) {
+          Future.delayed(
+            Duration.zero,
+            () {
               Provider.of<BookProvider>(context, listen: false)
                   .setSearchKeyword(value);
               Provider.of<BookProvider>(context, listen: false).getBooks();
             },
+          );
+        },
         leading: const Icon(Icons.search),
       ),
     );