factory User.fromJson(Map<String, dynamic> json) { return User( name: json['name']?.toString() ?? 'Unknown', age: int.tryParse(json['age']?.toString() ?? '') ?? 0, scores: (json['scores'] as List?) ?.map((e) => double.parse(e.toString())) .toList() ?? [], ); }

 factory User.fromJson(Map<String, dynamic> json) { return User( name: json.getString('name', defaultValue: 'Unknown'), age: json.getInt('age'), scores: json.getList<double>('scores'), ); }

bool isDateValid(DateTime? date) { if (date == null) return false; final now = DateTime.now(); return date.year == now.year && date.month == now.month && date.day == now.day; }

bool isDateValid(DateTime? date) { return date?.isToday ?? false; }

await Future<void>.delayed(const Duration(seconds: 3));

await 3.secondsDelay();

String getErrorMessage(int statusCode) { switch (statusCode) { case 429: return 'Too many requests. Please wait before trying again.'; case 404: return 'Resource not found. Please check the URL.'; case 500: return 'Server error. Please try again later.'; default: return 'An error occurred.'; } }

String getErrorMessage(int statusCode) { return statusCode.toHttpStatusUserMessage; }

List<String> processItems(List<dynamic>? items) { if (items == null) return []; final result = <String>[]; for (var i = 0; i < items.length; i++) { final item = items[i]; if (item != null) { result.add(item.toString()); } } return result; }

final processed = items?.convertTo<String>() ?? [];

import 'package:dart_helper_utils/dart_helper_utils.dart';

// String operations final text = "hello_world_example"; print(text.toCamelCase); // "helloWorldExample" // Safe number conversion final value = "123.45".tryToDouble() ?? 0.0; // Date handling final date = DateTime.now(); print(date.isToday); // true print(date.format("dd/MM/yyyy")); // "16/01/2025" // Collection utilities final list = [1, 2, null, 3, null, 4]; print(list.whereNotNull()); // [1, 2, 3, 4]

// Case conversions final text = "helloWorld_example-TEXT"; print(text.toPascalCase); // HelloWorldExampleText print(text.toSnakeCase); // hello_world_example_text print(text.toKebabCase); // hello-world-example-text print(text.toScreamingSnakeCase); // HELLO_WORLD_EXAMPLE_TEXT // String similarity checks final str1 = "hello"; final str2 = "hallo"; // Different algorithms available final similarity = str1.compareWith( str2, algorithm: StringSimilarityAlgorithm.levenshtein ); print(similarity); // 0.8 // Words extraction (smarter than simple split) print("FlutterAndDart_are-AWESOME".toWords); // [Flutter, And, Dart, are, AWESOME]

// Safe JSON parsing final jsonStr = '{"name":"John","age":"25","scores":[90,85,95]}'; final map = jsonStr.decode(); // Type-safe extractions final name = map.getString('name'); // "John" final age = map.getInt('age'); // 25 final scores = map.getList<int>('scores'); // [90, 85, 95] // Nested extractions final userData = { 'user': { 'details': { 'address': {'zipcode': '12345'} } } }; // Safe nested access with fallback final zipcode = userData.getInt( 'user', innerKey: 'details.address.zipcode', defaultValue: 0 ); // 12345 // Complex conversions final date = "2024-01-16".toDateTime(format: "yyyy-MM-dd"); final number = "1,234.56".toNum(format: "#,##0.00");

// Create a debouncer with 300ms delay final debouncer = Debouncer(delay: Duration(milliseconds: 300)); // Use in a search field TextField( onChanged: (value) { debouncer.run(() async { // This will only execute 300ms after the last keystroke await searchApi(value); }); }, ) // Don't forget to dispose @override void dispose() { debouncer.dispose(); super.dispose(); }

// Measure execution duration final duration = await TimeUtils.executionDuration(() async { await someExpensiveOperation(); }); print("Operation took ${duration.inMilliseconds}ms"); // Run with timeout try { final result = await TimeUtils.runWithTimeout( task: () => longRunningTask(), timeout: Duration(seconds: 5), ); } catch (e) { print('Task timed out'); } // Throttle function calls final throttled = TimeUtils.throttle( duration: Duration(seconds: 1), function: () => print('Throttled function called'), ); // Run periodic tasks final subscription = TimeUtils.runPeriodically( interval: Duration(minutes: 1), task: () => checkForUpdates(), ); // Clean up when done subscription.cancel();

final paginator = Paginator<MyItem>(items: myItems, pageSize: 10); // Access current page items final List<MyItem> currentPageItems = paginator.currentPageItems;

final asyncPaginator = AsyncPaginator<User>( fetchPage: (page, size) async => await api.fetchUsers(page: page, size: size), pageSize: 20, config: PaginationConfig( retryAttempts: 3, autoCancelFetches: true, // Highly recommended! ), ); // Access current page items (fetches if needed) final List<User> currentPageUsers = await asyncPaginator.currentPageItems;

final infinitePaginator = InfinitePaginator<Item, String>.cursorBased( fetchItems: (size, cursor) async => await api.fetchItems(size: size, fromCursor: cursor.value), getNextCursor: (items) => PaginationCursor(items.last.id), pageSize: 20, initialCursor: PaginationCursor(""), ); // Load more items await infinitePaginator.loadMoreItems();

final trackedPaginator = paginator with PaginationAnalytics; print(trackedPaginator.metrics); // Example: {pageLoads: 5, errors: 0, cacheHits: 3}

final date = DateTime.now(); // Quick comparisons print(date.isToday); // true print(date.isTomorrow); // false print(date.isYesterday); // false print(date.isWeekend); // depends on the date // Navigation final nextWeek = date.nextWeek; final prevMonth = date.previousMonth; final startOfDay = date.startOfDay; final endOfMonth = date.endOfMonth; // Duration calculations final otherDate = DateTime(2025, 12, 31); print(date.remainingDays(otherDate)); // days until otherDate print(date.passedDays(otherDate)); // days since otherDate // Formatting print(date.format('dd/MM/yyyy')); // "16/01/2025" print(date.httpFormat); // "Thu, 16 Jan 2025 00:00:00 GMT" // Age calculation final birthDate = DateTime(1990, 1, 1); print(birthDate.calculateAge()); // 35 (as of 2025)

// List Extensions final list = [1, 2, null, 3, null, 4]; print(list.whereNotNull()); // [1, 2, 3, 4] print(list.firstOrDefault(0)); // 1 print(list.distinctBy((e) => e)); // [1, 2, null, 3, 4] // Splitting lists print(list.firstHalf); // [1, 2, null] print(list.secondHalf); // [3, null, 4] // Map Extensions final map = {'name': 'John', 'scores': [85, 90, 95]}; // Safe extractions with defaults final name = map.getString('name', defaultValue: 'Unknown'); final scores = map.getList<int>('scores', defaultValue: []); // Manipulation map.setIfMissing('email', 'default@email.com'); final filtered = map.filter((key, value) => value != null); // Set Extensions final set = {1, 2, 3}; set.addIfNotNull(4); // Adds only if not null set.removeWhere((e) => e.isEven); // Removes even numbers // Common Iterable Extensions final items = [1, 2, 3, 4, 5]; print(items.total); // Sum: 15 print(items.tryGetRandom()); // Random element or null

// Basic Operations final num = 123.456; print(num.roundToNearest(5)); // 125 print(num.isBetween(100, 200)); // true // Numeric Checks print(42.isPrime); // false print(16.isPerfectSquare); // true print(8.isPerfectCube); // true // Currency and Formatting final price = 1234567.89; print(price.formatAsCurrency()); // "$1,234,567.89" print(price.formatAsCompact()); // "1.2M" print(price.asGreeks); // "1.23M" // Time Conversions await 5.secondsDelay(); // Delays for 5 seconds final duration = 30.asMinutes; // Duration of 30 minutes // HTTP Status Helpers print(200.isSuccessCode); // true print(404.isNotFoundError); // true print(429.statusCodeRetryDelay); // Suggested retry duration

// Smart Case Conversions final text = "helloWorld_example-TEXT"; print(text.toPascalCase); // HelloWorldExampleText print(text.toSnakeCase); // hello_world_example_text print(text.toDotCase); // hello.world.example.text // Validation print("test@email.com".isValidEmail); // true print("192.168.1.1".isValidIp4); // true print("https://dart.dev".isValidUrl); // true // Text Manipulation print(" hello world ".removeWhiteSpaces()); // "helloworld" print("hello".padCenter(10, '*')); // "**hello***" // Safe Operations final nullableText = null; print(nullableText.orEmpty); // "" print("".ifEmpty(() => "default")); // "default" // JSON Handling final jsonStr = '{"key": "value"}'; print(jsonStr.decode()); // Map<String, dynamic> print(jsonStr.tryDecode()); // Returns null if invalid

final statusCode = 404; // Status Checks print(statusCode.isSuccessCode); // false print(statusCode.isNotFoundError); // true print(statusCode.isRetryableError); // false // User Messages print(statusCode.toHttpStatusUserMessage); // "The requested resource could not be found. Please check the URL and try again." // Developer Messages print(statusCode.toHttpStatusDevMessage); // "Resource not found. Verify the path and parameters. Check if resource exists..." // Retry Handling if (statusCode.isRateLimitError) { final delay = statusCode.statusCodeRetryDelay; print("Retry after: ${delay.inSeconds} seconds"); }

// Create a list final list = DoublyLinkedList<int>([1, 2, 3, 4]); // Basic operations list.append(5); // Add to end list.prepend(0); // Add to start list.insert(1, 15); // Insert at position // Node operations for (final node in list.nodes) { print('Value: ${node.data}, ' 'Previous: ${node.prev?.data}, ' 'Next: ${node.next?.data}'); } // Factory constructors final filled = DoublyLinkedList.filled(3, 0); // [0, 0, 0] final generated = DoublyLinkedList.generate(3, (i) => i * 2); // [0, 2, 4] // Advanced operations list.reverse(); list.removeNodesWhere((node) => node.data.isEven); list.swapNodes(list.firstNode!, list.lastNode!);

// Common patterns print(RegExp(alphanumericPattern).hasMatch('Test123')); // true print(RegExp(specialCharsPattern).hasMatch('Test@123')); // true print(RegExp(usernamePattern).hasMatch('user_123')); // true print(RegExp(phoneNumberPattern).hasMatch('+1234567890')); // true // Validation using String extensions print("test@email.com".isValidEmail); // true print("192.168.1.1".isValidIp4); // true print("https://dart.dev".isValidUrl); // true print("12345".isNumeric); // true print("abcDEF".isAlpha); // true

// Time Constants print(oneSecond); // Duration(seconds: 1) print(oneMinute); // Duration(minutes: 1) print(oneHour); // Duration(hours: 1) print(oneDay); // Duration(days: 1) // Milliseconds Constants print(millisecondsPerSecond); // 1000 print(millisecondsPerMinute); // 60000 print(millisecondsPerHour); // 3600000 print(millisecondsPerDay); // 86400000 // Number Formats print(greekNumberSuffixes); // { // 'K': 1000, // 'M': 1000000, // 'B': 1000000000, // 'T': 1000000000000, // } // Calendar Constants print(smallWeekdays); // {1: 'Mon', 2: 'Tue', ...} print(fullWeekdays); // {1: 'Monday', 2: 'Tuesday', ...} print(smallMonthsNames); // {1: 'Jan', 2: 'Feb', ...} print(fullMonthsNames); // {1: 'January', 2: 'February', ...} // Roman Numerals print(romanNumerals); // {1: 'I', 5: 'V', 10: 'X', 50: 'L', 100: 'C', 500: 'D', 1000: 'M'}