Removed the use of the meta package and modernized the code.

.gitignore

@@ -15,3 +15,4 @@ build/
 
 # Directory created by dartdoc
 doc/api/
+.DS_Store

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.0.0
+
+- Bumped the minimum Dart version to 3.1.0, removed the use of the meta package, and modernized the code.
+
 ## 0.2.0
 
 - Expose helpers for querying NHTSA DB and accessing extended vehicle information (requested by @ride4sun, issue #8)

example/vin_decoder_example.dart

@@ -27,10 +27,10 @@ void main() async {
   print("Type is ${type}");
 
   var info = await NHTSA.decodeVin(vin.number);
-  print('Plant Country is ' + info.value('Plant Country'));
+  print('Plant Country is ${info?.value('Plant Country')}');
 
   var values = await NHTSA.decodeVinValues(vin.number);
-  print('Manufacturer from NHTSA DB is ' + values['Manufacturer']);
+  print('Manufacturer from NHTSA DB is ${values?['Manufacturer']}');
 
   var generated = VINGenerator().generate();
   print('Randomly Generated VIN is ${generated}');

lib/nhtsa.dart

@@ -1,5 +1,4 @@
 /// Support for querying NHTSA database by VIN.
-// @dart=2.1
 library nhtsa;
 
 export 'src/nhtsa_model.dart';

lib/src/nhtsa_model.dart

@@ -1,6 +1,7 @@
+import 'dart:convert';
+
 import 'package:basic_utils/basic_utils.dart';
 import 'package:http/http.dart' as http;
-import 'dart:convert';
 
 // NHTSA Results not relevant for a specific vehicle can be either null or N/A
 const String _RESULT_NOT_APPLICABLE = 'Not Applicable';
@@ -10,7 +11,7 @@ class NHTSA {
   static const String _uriBase = 'https://vpic.nhtsa.dot.gov/api/vehicles';
 
   /// Obtain information about a given [vin] from the NHTSA DB.
-  static Future<NHTSAVehicleInfo> decodeVin(String vin) async {
+  static Future<NHTSAVehicleInfo?> decodeVin(String vin) async {
     var path = _uriBase + '/DecodeVin/' + vin + '?format=json';
     final response = await http.get(Uri.parse(path));
 
@@ -22,7 +23,7 @@ class NHTSA {
   }
 
   /// Obtain a map of key/value pairs containing known values for a given [vin]
-  static Future<Map<String, dynamic>> decodeVinValues(String vin) async {
+  static Future<Map<String, dynamic>?> decodeVinValues(String vin) async {
     var path = _uriBase + '/DecodeVinValues/' + vin + '?format=json';
     final response = await http.get(Uri.parse(path));
 
@@ -56,15 +57,19 @@ class NHTSAResult {
   /// The ID number of a given [variable]
   int variableId;
 
-  NHTSAResult({this.value, this.valueId, this.variable, this.variableId});
+  NHTSAResult(
+      {required this.value,
+      required this.valueId,
+      required this.variable,
+      required this.variableId});
 
   /// Create a new [NHTSAResult] instance from a fixed JSON payload
-  NHTSAResult.fromJson(Map<String, dynamic> json) {
-    value = json['Value'];
-    valueId = json['ValueId'];
-    variable = json['Variable'];
-    variableId = json['VariableId'];
-  }
+  factory NHTSAResult.fromJson(Map<String, dynamic> json) => NHTSAResult(
+        value: json['Value'] ?? '',
+        valueId: json['ValueId'],
+        variable: json['Variable'],
+        variableId: json['VariableId'],
+      );
 
   @override
   String toString() {
@@ -80,13 +85,14 @@ class NHTSAVehicleInfo {
   List<NHTSAResult> results = [];
 
   NHTSAVehicleInfo(
-      {this.count, this.message, this.searchCriteria, this.results});
+      {required this.count,
+      required this.message,
+      required this.searchCriteria,
+      required this.results});
 
   /// Create a new [NHTSAVehicleInfo] instance from a fixed JSON payload
-  NHTSAVehicleInfo.fromJson(Map<String, dynamic> json) {
-    count = json['Count'];
-    message = json['Message'];
-    searchCriteria = json['SearchCriteria'];
+  factory NHTSAVehicleInfo.fromJson(Map<String, dynamic> json) {
+    final results = <NHTSAResult>[];
     if (json['Results'] != null) {
       json['Results'].forEach((v) {
         if (v['Value'] != null &&
@@ -96,6 +102,13 @@ class NHTSAVehicleInfo {
         }
       });
     }
+
+    return NHTSAVehicleInfo(
+      count: json['Count'],
+      message: json['Message'],
+      searchCriteria: json['SearchCriteria'],
+      results: results,
+    );
   }
 
   static String _normalizeStringValue(String s) {
@@ -104,17 +117,16 @@ class NHTSAVehicleInfo {
   }
 
   /// Lookup the value of a variable by its [variableId] in the NHTSA DB results
-  String valueFromId(int variableId) {
-    var result = results.singleWhere((e) => e.variableId == variableId,
-        orElse: () => null);
-    return result != null ? _normalizeStringValue(result.value) : null;
+  String? valueFromId(int variableId) {
+    final index =
+        results.indexWhere((element) => element.variableId == variableId);
+    return index == -1 ? null : _normalizeStringValue(results[index].value);
   }
 
   /// Lookup the value of a named [variable] in the NHTSA DB results
-  String value(String variable) {
-    var result =
-        results.singleWhere((e) => e.variable == variable, orElse: () => null);
-    return result != null ? _normalizeStringValue(result.value) : null;
+  String? value(String variable) {
+    final index = results.indexWhere((element) => element.variable == variable);
+    return index == -1 ? null : _normalizeStringValue(results[index].value);
   }
 
   @override

lib/src/vin_decoder_base.dart

@@ -2,8 +2,6 @@ import 'manufacturers.dart';
 import 'nhtsa_model.dart';
 import 'year_map.dart';
 
-import 'package:meta/meta.dart';
-
 class VIN {
   /// The VIN that the class was instantiated with.
   final String number;
@@ -21,14 +19,14 @@ class VIN {
   final bool extended;
   Map<String, dynamic> _vehicleInfo = {};
 
-  VIN({@required this.number, this.extended = false})
+  VIN({required this.number, this.extended = false})
       : wmi = normalize(number).substring(0, 3),
         vds = normalize(number).substring(3, 9),
         vis = normalize(number).substring(9, 17);
 
   /// Carry out VIN validation. A valid [number] must be 17 characters long
   /// and contain only valid alphanumeric characters.
-  bool valid([String number]) {
+  bool valid([String? number]) {
     String value = normalize(number != null ? number : this.number);
     return RegExp(r"^[a-zA-Z0-9]+$").hasMatch(value) && value.length == 17;
   }
@@ -39,7 +37,7 @@ class VIN {
 
   /// Obtain the encoded manufacturing year in YYYY format.
   int getYear() {
-    return yearMap[modelYear()];
+    return yearMap[modelYear()] ?? 0;
   }
 
   /// Obtain the 2-character region code for the manufacturing region.
@@ -69,13 +67,13 @@ class VIN {
   String getManufacturer() {
     // Check for the standard case - a 3 character WMI
     if (manufacturers.containsKey(this.wmi)) {
-      return manufacturers[this.wmi];
+      return manufacturers[this.wmi] ?? '';
     } else {
       // Some manufacturers only use the first 2 characters for manufacturer
       // identification, and the third for the class of vehicle.
       var id = this.wmi.substring(0, 2);
       if (manufacturers.containsKey(id)) {
-        return manufacturers[id];
+        return manufacturers[id] ?? '';
       } else {
         return "Unknown (WMI: ${this.wmi.toUpperCase()})";
       }
@@ -85,7 +83,7 @@ class VIN {
   /// Returns the checksum for the VIN. Note that in the case of the EU region
   /// checksums are not implemented, so this becomes a no-op. More information
   /// is provided in ISO 3779:2009.
-  String getChecksum() {
+  String? getChecksum() {
     return (getRegion() != "EU") ? normalize(this.number)[8] : null;
   }
 
@@ -100,7 +98,7 @@ class VIN {
 
   Future<void> _fetchExtendedVehicleInfo() async {
     if (this._vehicleInfo.isEmpty && extended == true) {
-      this._vehicleInfo = await NHTSA.decodeVinValues(this.number);
+      this._vehicleInfo = await NHTSA.decodeVinValues(this.number) ?? {};
     }
   }
 

lib/vin_decoder.dart

@@ -1,5 +1,4 @@
-/// Support for VIN parsing, validation, and generation.
-// @dart=2.1
+/// Support for VIN parsing, validation, and generation
 
 library vin_decoder;
 

pubspec.yaml

@@ -2,19 +2,17 @@ name: vin_decoder
 description:
   Dart library for working with Vehicle Identification Numbers (VINs) based on ISO 3779:2009 and
   World Manufacturer Identifiers (WMIs) based on ISO 3780:2009, enriched by NHTSA data.
-
-version: 0.1.4+1
+version: 2.0.0
 repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 
 environment:
-  sdk: '>=2.1.0 <3.0.0'
+  sdk: '>=3.1.0 <4.0.0'
 
 dependencies:
-  meta: ^1.4.0
-  basic_utils: ^3.4.0
-  http: ^0.13.3
-  random_string: ^2.1.0
+  basic_utils: ^5.7.0
+  http: ^1.2.1
+  random_string: ^2.3.1
 
 dev_dependencies:
-  test: ^1.15.7
+  test: ^1.25.7

test/vin_generator_test.dart

@@ -4,15 +4,15 @@ import 'package:test/test.dart';
 void main() {
   group('VIN Generator Test', () {
     VINGenerator generator;
-    VIN vin;
+    VIN? vin;
 
     setUp(() {
       generator = VINGenerator();
       vin = VIN(number: generator.generate());
     });
 
     test('Validity Test', () {
-      expect(vin.valid(), isTrue);
+      expect(vin!.valid(), isTrue);
     });
   });
 }