save before flutter upgrade

lib/models/content_manager/book.dart

@@ -0,0 +1,69 @@
+import 'dart:convert';
+
+class Book {
+  int bookId;
+  String title;
+  String bookDescription;
+  DateTime createdAt;
+  String book;
+  String bookCover;
+  String size;
+  String year;
+  String bookStatus;
+  int autorId;
+  String autorFirstName;
+  String? autorLastName;
+  String category;
+
+  Book({
+    required this.bookId,
+    required this.title,
+    required this.bookDescription,
+    required this.createdAt,
+    required this.book,
+    required this.bookCover,
+    required this.size,
+    required this.year,
+    required this.bookStatus,
+    required this.autorId,
+    required this.autorFirstName,
+    required this.autorLastName,
+    required this.category,
+  });
+
+  factory Book.fromJson(String str) => Book.fromMap(json.decode(str));
+
+  String toJson() => json.encode(toMap());
+
+  factory Book.fromMap(Map<String, dynamic> json) => Book(
+        bookId: json["book_id"],
+        title: json["title"],
+        bookDescription: json["book_description"],
+        createdAt: DateTime.parse(json["created_at"]),
+        book: json["book"],
+        bookCover: json["book_cover"],
+        size: json["size"],
+        year: json["year"],
+        bookStatus: json["book_status"],
+        autorId: json["autor_id"],
+        autorFirstName: json["autor_first_name"],
+        autorLastName: json["autor_last_name"],
+        category: json["category"],
+      );
+
+  Map<String, dynamic> toMap() => {
+        "book_id": bookId,
+        "title": title,
+        "book_description": bookDescription,
+        "created_at": createdAt.toIso8601String(),
+        "book": book,
+        "book_cover": bookCover,
+        "size": size,
+        "year": year,
+        "book_status": bookStatus,
+        "autor_id": autorId,
+        "autor_first_name": autorFirstName,
+        "autor_last_name": autorLastName,
+        "category": category,
+      };
+}