dartson

Dartson is a dart library which converts Dart Objects into their JSON representation. It helps you keep your code clean of fromJSON and toJSON functions by using dart:mirrors reflection. It works after dart2js compiling.

NOTICE: The dart2js functionality works since Dart SDK 1.1.0.

A faster version of parsing the object is currently under development. It will provide fromJson and toJson methods after compilation using transformers.

Latest changes

• dartson now supports custom transformer for specific type / an example for a basic DateTime converter can be found in:

Serializing objects in dart

library example;

import 'package:dartson/dartson.dart';

@MirrorsUsed(targets:const['example'],override:'*')
import 'dart:mirrors';

class EntityClass {
  String name;
  
  @DartsonProperty(name:"renamed")
  bool otherName;
  
  @DartsonProperty(ignore:true)
  String notVisible;
  
  // private members are never serialized
  String _private = "name";
  
  String get doGetter => _private;
}

void main() {
  EntityClass object = new EntityClass();
  object.name = "test";
  object.otherName = "blub";
  object.notVisible = "hallo";
  
  String jsonString = serialize(object);
  print(jsonString);
  // will return: '{"name":"test","renamed":"blub","doGetter":"name"}'
}

Parsing json to dart object

library example;

import 'package:dartson/dartson.dart';

@MirrorsUsed(targets:const['example'],override:'*')
import 'dart:mirrors';

class EntityClass {
  String name;
  String _setted;
  
  @DartsonProperty(name:"renamed")
  bool otherName;
  
  @DartsonProperty(ignore:true)
  String notVisible;
  
  List<EntityClass> children;
  
  set setted(String s) => _setted = s;
  String get setted => _setted;
}

void main() {
  EntityClass object = parse('{"name":"test","renamed":"blub","notVisible":"it is", "setted": "awesome"}', EntityClass);
  
  print(object.name); // > test
  print(object.otherName); // > blub
  print(object.notVisible); // > it is
  print(object.setted); // > awesome
  
  // to parse a list of items use [parseList]
  List<EntityClass> list = parseList('[{"name":"test", "children": [{"name":"child1"},{"name":"child2"}]},{"name":"test2"}]', EntityClass);
  print(list.length); // > 2
  print(list[0].name); // > test
  print(list[0].children[0].name); // > child1
}

Mapping Maps and Lists to dart objects

Frameworks like Angular.dart come with several HTTP services which already transform the HTTP response to a map using JSON.encode. To use those encoded Maps or Lists use map and mapList.

library example;

import 'package:dartson/dartson.dart';

@MirrorsUsed(targets:const['example'],override:'*')
import 'dart:mirrors';

class EntityClass {
  String name;
  String _setted;
  
  @DartsonProperty(name:"renamed")
  bool otherName;
  
  @DartsonProperty(ignore:true)
  String notVisible;
  
  List<EntityClass> children;
  
  set setted(String s) => _setted = s;
  String get setted => _setted;
}

void main() {
  EntityClass object = map({"name":"test","renamed":"blub","notVisible":"it is", "setted": "awesome"}, EntityClass);  
  print(object.name); // > test
  print(object.otherName); // > blub
  print(object.notVisible); // > it is
  print(object.setted); // > awesome
  
  // to parse a list of items use [parseList]
  List<EntityClass> list = mapList([{"name":"test", "children": [{"name":"child1"},{"name":"child2"}]},{"name":"test2"}], EntityClass);
  print(list.length); // > 2
  print(list[0].name); // > test
  print(list[0].children[0].name); // > child1
}

Writting custom TypeTransformers

Transformers are used to encode / decode none serializable types that shouldn't be treated as objects / lists (for example DateTime).

/**
 * A simple DateTime transformer which uses the toString() method.
 */
class DateTimeParser<T> extends TypeTransformer {
  T decode(dynamic value) {
    return DateTime.parse(value);
  }

  dynamic encode(T value) {
    return value.toString();
  }
}

In order to use the TypeTransformer you need to register the transformer in a main function:

// ...
void main() {
  registerTransformer(new DateTimeParser<DateTime>());
}

Use default transformers

library test;

import 'package:dartson/dartson.dart';
import 'package:dartson/default_transformers.dart' as dd;

void main() {
  dd.register();
}

Roadmap

dart2js

I'm thinking of a transformer which saves the hole mirrors reflection and increases the performance. It also should reduce the JavaScript size.

Custom serializing handler (implemented since 0.1.5)

Version 0.2.0 will have the functionality to define the way you want to encode / decode specific types.

TODO

• Better dart2js solution
• Handle recrusive errors