object_serializer 0.3.2

A serializer (with caching support) of any static (generic) complex data that can be represented as simpler data.

object_serializer

A collection of serializers for serializing data in a variety of ways (JSON, Generic Objects).

Version: 0.3.2

Two kinds of data serializers are currently available:

• JSON serializer
• Object serializer

JSON serializer is a serializer to standard JSON format. Serialization is supported for types that can be converted to simpler data types (eg. BigInt, DateTime, Duration, Uri etc). The working principle is simple. You yourself choose the method of serialization and deserialization of data, that is, you completely control this process.

Object serializer is a serializer (with caching support) of any static (generic) complex data that can be represented as simpler data.

Allows you to implement a serializer for any data that can be transferred between isolates or even over the Internet.
The principle of operation is very simple, for each data type you need to implement your own object serializer.

Implementing an object serializer is also very simple. To do this, you need to write the data in a strict order and then read this data in the same order.

JSON serializer

JSON serializer is a serializer to standard JSON format.
Let's say that we need to use this data objects to exchange data in JSON format.

Post:
  fields:
    id: int
    user: User
    text: String
    comments: List<int>?

User:
  fields:
    id: int
    name: String
    age: int?

Now let's try to generate the code.
We will use a generator for this.

import 'dart:io';

import 'package:object_serializer/json_serializer_generator.dart';
import 'package:yaml/yaml.dart';

void main() {
  final classes = loadYaml(_classes) as Map;
  final serializers = loadYaml(_serializers) as Map;
  final g = JsonSerializerGenerator();
  final classesCode = g.generateClasses(
    classes,
    serializers: serializers,
  );
  final serializersCode = g.generateSerializers(
    serializers,
  );
  final enums = loadYaml(_enums) as Map;
  final enumCode = g.generateEnums(enums);
  final values = {
    'classes': classesCode,
    'enums': enumCode,
    'serializers': serializersCode,
  };

  var source = g.render(_template, values);
  source = g.format(source);
  File('example/small_example.dart').writeAsStringSync(source);
}

const _classes = '''
Post:
  fields:
    id: int
    user: User
    text: String
    comments: List<int>?

User:
  fields:
    id: int
    name: String
    age: int?
''';

const _enums = '''
{}
''';

const _serializers = '''
{}
''';

const _template = r'''
import 'dart:convert';

void main(List<String> args) {
  final user = User(
    id: 1,
    name: "Jack",
    age: null,
  );

  final post1 = Post(
    id: 1,
    user: user,
    text: 'Hello!',
    comments: [123, 456],
  );

  final post2 = Post(
    id: 2,
    user: user,
    text: 'Goodbye!',
    comments: null,
  );

  final input = Post.toJsonList([post1, post2]);
  final json = jsonEncode(input);
  final output = jsonDecode(json);
  final posts = Post.fromJsonList(output as List);
  print(json);
  print('Posts: ${posts.length}');
  print('Users: ${posts.map((e) => e.user.name)}');
}

{{classes}}

{{enums}}

{{serializers}}
''';

Generated source code:

import 'dart:convert';

void main(List<String> args) {
  final user = User(
    id: 1,
    name: "Jack",
    age: null,
  );

  final post1 = Post(
    id: 1,
    user: user,
    text: 'Hello!',
    comments: [123, 456],
  );

  final post2 = Post(
    id: 2,
    user: user,
    text: 'Goodbye!',
    comments: null,
  );

  final input = Post.toJsonList([post1, post2]);
  final json = jsonEncode(input);
  final output = jsonDecode(json);
  final posts = Post.fromJsonList(output as List);
  print(json);
  print('Posts: ${posts.length}');
  print('Users: ${posts.map((e) => e.user.name)}');
}

class Post {
  Post(
      {required this.id,
      required this.user,
      required this.text,
      required this.comments});

  factory Post.fromJson(Map json) {
    return Post(
      id: json['id'] as int,
      user: User.fromJson(json['user'] as Map),
      text: json['text'] as String,
      comments: json['comments'] == null
          ? null
          : (json['comments'] as List).map((e) => e as int).toList(),
    );
  }

  final int id;

  final User user;

  final String text;

  final List<int>? comments;

  static List<Post> fromJsonList(List json) {
    return json.map((e) => Post.fromJson(e as Map)).toList();
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'user': user.toJson(),
      'text': text,
      'comments': comments,
    };
  }

  static List<Map<String, dynamic>> toJsonList(List<Post> list) {
    return list.map((e) => e.toJson()).toList();
  }
}

class User {
  User({required this.id, required this.name, required this.age});

  factory User.fromJson(Map json) {
    return User(
      id: json['id'] as int,
      name: json['name'] as String,
      age: json['age'] == null ? null : 0,
    );
  }

  final int id;

  final String name;

  final int? age;

  static List<User> fromJsonList(List json) {
    return json.map((e) => User.fromJson(e as Map)).toList();
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'name': name,
      'age': age,
    };
  }

  static List<Map<String, dynamic>> toJsonList(List<User> list) {
    return list.map((e) => e.toJson()).toList();
  }
}

The result of executing the generated code:

[{"id":1,"user":{"id":1,"name":"Jack","age":null},"text":"Hello!","comments":[123,456]},{"id":2,"user":{"id":1,"name":"Jack","age":null},"text":"Goodbye!","comments":null}] Posts: 2 Users: (Jack, Jack)

Object serializer

Object serializer is a serializer (with caching support) of any static (generic) complex data that can be represented as simpler data.
Example of simple object serializer:

class _UriSerializer extends ObjectSerializer<Uri> {
  @override
  Uri deserialize(Deserializer deserializer) {
    return Uri.parse(deserializer.readObject());
  }

  @override
  void serialize(Serializer serializer, Uri object) {
    serializer.writeObject(object.toString());
  }
}

This is not an analogue or replacement for the JSON serializer.
In this case, the data is serialized into a so-called stream and, if necessary, cached.

For example, you can serialize such data.

typedef _ComplexType = Map<Uri, List<Tuple2<BigInt, Tuple2<int, Base?>>>>;

class A extends Base {
  A(super.base);

  @override
  bool operator ==(other) => other is A && other.base == base;
}

class B extends Base {
  final int x;

  B(super.base, this.x);

  @override
  bool operator ==(other) => other is B && other.base == base && other.x == x;
}

class Base {
  final String base;

  Base(this.base);
}

For example, such data can be serialized.

final _ComplexType map = {
  Uri.parse('package:animals'): [
    Tuple2(BigInt.parse('1'), Tuple2(1, A('Hello'))),
    Tuple2(BigInt.parse('2'), Tuple2(1, A('Hello'))),
  ],
  Uri.parse('package:zoo'): [
    Tuple2(BigInt.parse('1'), Tuple2(1, B('Goodbye', 41))),
    Tuple2(BigInt.parse('2'), Tuple2(2, null)),
    Tuple2(BigInt.parse('1'), Tuple2(1, A('Hello'))),
  ],
};

Output data stream:

[1, 4, 2, 4, 16, 6, 8, package:animals, 9, 9, 2, 12, 11, 14, 15, 16, 8, 1, 19, 12, 21, 2, 1, 24, 13, 26, 8, Hello, 29, 11, 31, 15, 33, 8, 2, 36, 12, 21, 39, 13, 26, 42, 16, 44, 8, package:zoo, 47, 9, 3, 50, 11, 14, 53, 12, 21, 56, 14, 58, 8, Goodbye, 61, 2, 41, 64, 11, 31, 67, 12, 69, 2, 2, 72, 6, 74, 11, 14, 77, 12, 21, 80, 13, 26]

Full example:

import 'dart:isolate';

import 'package:object_serializer/object_serializer.dart';
import 'package:object_serializer/serialize.dart';
import 'package:test/test.dart';
import 'package:tuple/tuple.dart';

Future<void> main() async {
  test(
    'Example',
    () async {
      final _ComplexType map = {
        Uri.parse('package:animals'): [
          Tuple2(BigInt.parse('1'), Tuple2(1, A('Hello'))),
          Tuple2(BigInt.parse('2'), Tuple2(1, A('Hello'))),
        ],
        Uri.parse('package:zoo'): [
          Tuple2(BigInt.parse('1'), Tuple2(1, B('Goodbye', 41))),
          Tuple2(BigInt.parse('2'), Tuple2(2, null)),
          Tuple2(BigInt.parse('1'), Tuple2(1, A('Hello'))),
        ],
      };

      final stream = serializeMap(map, _collection);

      //
      final port = ReceivePort();
      final isolate =
          await Isolate.spawn<List>(compute, [port.sendPort, stream]);
      final stream2 = await port.first as List;
      isolate.kill(priority: Isolate.immediate);

      //
      final _ComplexType result = deserializeMap(stream2, _collection);
      expect(result, map);
    },
  );
}

final _collection = ObjectSerializerCollection()
  ..addSerializer(ListSerializer<Tuple2<BigInt, Tuple2<int, Base?>>>())
  ..addSerializer(_ASerializer())
  ..addSerializer(_BSerializer())
  ..addSerializer(_BigIntSerializer())
  ..addSerializer(_Tuple2Serializer<BigInt, Tuple2<int, Base?>>())
  ..addSerializer(_Tuple2Serializer<int, Base?>())
  ..addSerializer(_UriSerializer());

void compute(List args) {
  final sendPort = args[0] as SendPort;
  final input = args[1] as List;
  final _ComplexType map = deserializeMap(input, _collection);
  final output = serializeMap(map, _collection);
  sendPort.send(output);
}

typedef _ComplexType = Map<Uri, List<Tuple2<BigInt, Tuple2<int, Base?>>>>;

class A extends Base {
  A(super.base);

  @override
  bool operator ==(other) => other is A && other.base == base;
}

class B extends Base {
  final int x;

  B(super.base, this.x);

  @override
  bool operator ==(other) => other is B && other.base == base && other.x == x;
}

class Base {
  final String base;

  Base(this.base);
}

class _ASerializer extends ObjectSerializer<A> {
  @override
  A deserialize(Deserializer deserializer) {
    return A(
      deserializer.readObject(),
    );
  }

  @override
  void serialize(Serializer serializer, A object) {
    serializer.writeObject(object.base);
  }
}

class _BigIntSerializer extends ObjectSerializer<BigInt> {
  @override
  BigInt deserialize(Deserializer deserializer) {
    return BigInt.parse(deserializer.readObject());
  }

  @override
  void serialize(Serializer serializer, BigInt object) {
    serializer.writeObject('$object');
  }
}

class _BSerializer extends ObjectSerializer<B> {
  @override
  B deserialize(Deserializer deserializer) {
    return B(
      deserializer.readObject(),
      deserializer.readObject(),
    );
  }

  @override
  void serialize(Serializer serializer, B object) {
    serializer.writeObject(object.base);
    serializer.writeObject(object.x);
  }
}

class _Tuple2Serializer<T1, T2> extends ObjectSerializer<Tuple2<T1, T2>> {
  @override
  Tuple2<T1, T2> deserialize(Deserializer deserializer) {
    return Tuple2(
      deserializer.readObject(),
      deserializer.readObject(),
    );
  }

  @override
  void serialize(Serializer serializer, Tuple2<T1, T2> object) {
    serializer.writeObject(object.item1);
    serializer.writeObject(object.item2);
  }
}

class _UriSerializer extends ObjectSerializer<Uri> {
  @override
  Uri deserialize(Deserializer deserializer) {
    return Uri.parse(deserializer.readObject());
  }

  @override
  void serialize(Serializer serializer, Uri object) {
    serializer.writeObject(object.toString());
  }
}

For simpler or non-generic data, fewer serializers are required. But, in any case, each data requires its own serializer.

This allows any type of data to be serialized. For example, you can serialize a parsed AST.
The main goal is to make it easier to write serializers to pass data between isolates.