object_serializer

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

Version: 0.1.5

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

Let’s say that we need to use this data objects.

class Company {
  final String name;

  final Uri website;

  Company({
    required this.name,
    required this.website,
  });
}

class Customer {
  final int? age;

  final DateTime? birthday;

  final Duration frequency;

  final CustomerLevel level;

  final String name;

  Customer({
    required this.age,
    required this.birthday,
    required this.frequency,
    required this.level,
    required this.name,
  });
}

enum CustomerLevel { retail, wholesale }

class Order {
  final BigInt amount;

  final Company company;

  final Customer customer;

  final DateTime date;

  final List<OrderLine> lines;

  Order({
    required this.amount,
    required this.company,
    required this.customer,
    required this.date,
    required this.lines,
  });
}

class OrderLine {
  final Product product;

  final BigInt price;

  final int quantity;

  final BigInt total;

  OrderLine({
    required this.product,
    required this.price,
    required this.quantity,
    required this.total,
  });
}

class Product {
  final String name;

  final BigInt price;

  final Map<String, double> priceRange;

  Product({
    required this.name,
    required this.price,
    required this.priceRange,
  });
}

How to implement serializers for these data types in less than 30 minutes? Let’s try to do this.

class _BigIntSerializer extends JsonSerializer<BigInt> {
  @override
  BigInt deserialize(Deserializer deserializer, Object? value) {
    final json = cast<String>(value);
    return BigInt.parse(json);
  }

  @override
  String serialize(Serializer serializer, BigInt value) {
    return value.toString();
  }
}

class _CompanySerializer extends JsonSerializer<Company> {
  @override
  Company deserialize(Deserializer deserializer, Object? value) {
    final json = cast<Map>(value);
    return Company(
      name: deserializer.deserialize(json['name']),
      website: deserializer.deserialize(json['website']),
    );
  }

  @override
  Map<String, dynamic> serialize(Serializer serializer, Company value) {
    return {
      'name': serializer.serialize(value.name),
      'website': serializer.serialize(value.website),
    };
  }
}

class _CustomerLevelSerializer extends JsonSerializer<CustomerLevel> {
  @override
  CustomerLevel deserialize(Deserializer deserializer, Object? value) {
    final json = cast<int>(value);
    return CustomerLevel.values[json];
  }

  @override
  int serialize(Serializer serializer, CustomerLevel value) {
    return value.index;
  }
}

class _CustomerSerializer extends JsonSerializer<Customer> {
  @override
  Customer deserialize(Deserializer deserializer, Object? value) {
    final json = cast<Map>(value);
    return Customer(
      birthday: deserializer.deserialize(json['birthday']),
      age: deserializer.deserialize(json['age']),
      frequency: deserializer.deserialize(json['frequency']),
      level: deserializer.deserialize(json['level']),
      name: deserializer.deserialize(json['name']),
    );
  }

  @override
  Map<String, dynamic> serialize(Serializer serializer, Customer value) {
    return {
      'age': serializer.serialize(value.age),
      'birthday': serializer.serialize(value.birthday),
      'frequency': serializer.serialize(value.frequency),
      'level': serializer.serialize(value.level),
      'name': serializer.serialize(value.name),
    };
  }
}

class _DateTimeSerializer extends JsonSerializer<DateTime> {
  @override
  DateTime deserialize(Deserializer deserializer, Object? value) {
    final json = cast<String>(value);
    return DateTime.fromMicrosecondsSinceEpoch(int.parse(json));
  }

  @override
  String serialize(Serializer serializer, DateTime value) {
    return value.microsecondsSinceEpoch.toString();
  }
}

class _DurationSerializer extends JsonSerializer<Duration> {
  @override
  Duration deserialize(Deserializer deserializer, Object? value) {
    final json = cast<String>(value);
    return Duration(microseconds: int.parse(json));
  }

  @override
  String serialize(Serializer serializer, Duration value) {
    return value.inMicroseconds.toString();
  }
}

class _OrderLineSerializer extends JsonSerializer<OrderLine> {
  @override
  OrderLine deserialize(Deserializer deserializer, Object? value) {
    final json = cast<Map>(value);
    return OrderLine(
      price: deserializer.deserialize(json['price']),
      product: deserializer.deserialize(json['product']),
      quantity: deserializer.deserialize(json['quantity']),
      total: deserializer.deserialize(json['total']),
    );
  }

  @override
  Map<String, dynamic> serialize(Serializer serializer, OrderLine value) {
    return {
      'price': serializer.serialize(value.price),
      'product': serializer.serialize(value.product),
      'quantity': serializer.serialize(value.quantity),
      'total': serializer.serialize(value.total),
    };
  }
}

class _OrderSerializer extends JsonSerializer<Order> {
  @override
  Order deserialize(Deserializer deserializer, Object? value) {
    final json = cast<Map>(value);
    return Order(
      amount: deserializer.deserialize(json['amount']),
      company: deserializer.deserialize(json['company']),
      customer: deserializer.deserialize(json['customer']),
      date: deserializer.deserialize(json['date']),
      lines: deserializer.deserializeList(json['lines']),
    );
  }

  @override
  Map<String, dynamic> serialize(Serializer serializer, Order value) {
    return {
      'amount': serializer.serialize(value.amount),
      'company': serializer.serialize(value.company),
      'customer': serializer.serialize(value.customer),
      'date': serializer.serialize(value.date),
      'lines': serializer.serializeList(value.lines),
    };
  }
}

class _ProductSerializer extends JsonSerializer<Product> {
  @override
  Product deserialize(Deserializer deserializer, Object? value) {
    final json = cast<Map>(value);
    return Product(
      name: deserializer.deserialize(json['name']),
      price: deserializer.deserialize(json['price']),
      priceRange: deserializer.deserializeMap(json['priceRange']),
    );
  }

  @override
  Map<String, dynamic> serialize(Serializer serializer, Product value) {
    return {
      'name': serializer.serialize(value.name),
      'price': serializer.serialize(value.price),
      'priceRange': serializer.serializeMap(value.priceRange),
    };
  }
}

class _UriSerializer extends JsonSerializer<Uri> {
  @override
  Uri deserialize(Deserializer deserializer, Object? value) {
    final json = cast<String>(value);
    return Uri.parse(json);
  }

  @override
  String serialize(Serializer serializer, Uri value) {
    return value.toString();
  }
}

About 180 lines of code. Not much, given that you have complete control over what and how to serialize.

Let’s see the result of this work in action. The simplest test:

import 'dart:convert';

import 'package:object_serializer/json_serializer.dart';

void main(List<String> args) {
  final price = BigInt.from(29.99);
  final order = Order(
    amount: price,
    company: _company,
    customer: _customer,
    date: DateTime.now(),
    lines: [
      OrderLine(
          product: _product,
          price: price,
          quantity: 25,
          total: price * BigInt.from(25))
    ],
  );

  final orders = [order, order];
  final jsonObject = serializeList(orders, _collection);
  final jsonString = jsonEncode(jsonObject);
  final jsonObject2 = jsonDecode(jsonString);
  final orders2 = deserializeList<Order>(jsonObject2, _collection);
  final jsonObject3 = serializeList(orders2, _collection);
  final jsonString2 = jsonEncode(jsonObject3);
  final result = jsonString == jsonString2;
  print(jsonString2);
  print('Test passed: $result');
}

final _collection = JsonSerializerCollection()
  ..addSerializer(_BigIntSerializer())
  ..addSerializer(_CompanySerializer())
  ..addSerializer(_CustomerLevelSerializer())
  ..addSerializer(_CustomerSerializer())
  ..addSerializer(_DateTimeSerializer())
  ..addSerializer(_DurationSerializer())
  ..addSerializer(_OrderLineSerializer())
  ..addSerializer(_OrderSerializer())
  ..addSerializer(_ProductSerializer())
  ..addSerializer(_UriSerializer());

final _company = Company(
  name: 'ACME Inc.',
  website: Uri.parse('https://acme.com'),
);

final _customer = Customer(
  age: null,
  birthday: null,
  frequency: Duration(days: 10),
  level: CustomerLevel.wholesale,
  name: 'Peter Pan',
);

final _product = Product(
  name: 'The Little White Bird',
  price: BigInt.from(49.99),
  priceRange: {
    '3': 49.99,
    '10': 39.99,
    '25': 29.99,
  },
);

Result pf work:

[{“amount”:”29″,”company”:{“name”:”ACME Inc.”,”website”:”https://acme.com”},”customer”:{“age”:null,”birthday”:null,”frequency”:”864000000000″,”level”:1,”name”:”Peter Pan”},”date”:”1658504965053872″,”lines”:[{“price”:”29″,”product”:{“name”:”The Little White Bird”,”price”:”49″,”priceRange”:{“3″:49.99,”10″:39.99,”25″:29.99}},”quantity”:25,”total”:”725″}]},{“amount”:”29″,”company”:{“name”:”ACME Inc.”,”website”:”https://acme.com”},”customer”:{“age”:null,”birthday”:null,”frequency”:”864000000000″,”level”:1,”name”:”Peter Pan”},”date”:”1658504965053872″,”lines”:[{“price”:”29″,”product”:{“name”:”The Little White Bird”,”price”:”49″,”priceRange”:{“3″:49.99,”10″:39.99,”25″:29.99}},”quantity”:25,”total”:”725″}]}] Test passed: true