JSON God v2

version 2.0.0-beta

The new and improved definitive solution for JSON in Dart.


    json_god: ^2.0.0-beta


It is recommended to import the library under an alias, i.e., god.

import 'package:json_god/json_god.dart' as god;

// Set .debug to true to print VERY VERBOSE debug output.
// god.debug = true;

Dart2JS Compatibility

IMPORTANT - Reflection through dart:mirrors is not yet perfect in Dart2JS. Make sure to add a @MirrorsUsed() annotation to any classes you want to serialize/deserialize.

library app;

@MirrorsUsed(targets: 'app')
import 'dart:mirrors';

@MirrorsUsed documentation can be found here.

Serializing JSON

Simply call god.serialize(x) to synchronously transform an object into a JSON string.

Map map = {"foo": "bar", "numbers": [1, 2, {"three": 4}]};

// Output: {"foo":"bar","numbers":[1,2,{"three":4]"}
String json = god.serialize(map);

You can easily serialize classes, too. JSON God also supports classes as members.

class A {
    String foo;

class B {
    String hello;
    A nested;
    B(String hello, String foo) {
      this.hello = hello;
      this.nested = new A(foo);

main() {
    God god = new God();
    print(god.serialize(new B("world", "bar")));

// Output: {"hello":"world","nested":{"foo":"bar"}}

If a class has a toJson method, it will be called instead.

Deserializing JSON

Deserialization is equally easy, and is provided through god.deserialize.

Map map = god.deserialize('{"hello":"world"}');
int three = god.deserialize("3");

Deserializing to Classes

JSON God lets you deserialize JSON into an instance of any type. Simply pass the type as the second argument to god.deserialize.

If the class has a fromJson constructor, it will be called instead.

class Child {
  String foo;

class Parent {
  String hello;
  Child child = new Child();

main() {
  God god = new God();
  Parent parent = god.deserialize('{"hello":"world","child":{"foo":"bar"}}', Parent);

Any JSON-deserializable classes must initializable without parameters. If new Foo() would throw an error, then you can't use Foo with JSON.

This allows for validation of a sort, as only fields you have declared will be accepted.

class HasAnInt { int theInt; }

HasAnInt invalid = god.deserialize('["some invalid input"]', HasAnInt);
// Throws an error


You can also enforce validation rules, thanks to the json_schema package. Both serialize and deserialize support a named parameter, schema. Alternatively, use the WithSchema or WithSchemaUrl annotations on your classes.

@WithSchema(const {})


An exception will be thrown if validation fails.

Thank you for using JSON God

Thank you for using this library. I hope you like it.

Feel free to follow me on Twitter: @thosakwe

Or, check out my blog



A robust library for JSON serialization and deserialization.