108 lines
3 KiB
Markdown
108 lines
3 KiB
Markdown
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# Belatuk JSON Serializer
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[](https://dart.dev/null-safety)
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[](https://gitter.im/angel_dart/discussion)
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[](https://github.com/dart-backend/belatuk-common-utilities/blob/main/packages/json_serializer/LICENSE)
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**Replacement of `package:json_god` with breaking changes to support NNBD.**
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The ***new and improved*** definitive solution for JSON in Dart. It supports synchronously transform an object into a JSON string and also deserialize a JSON string back into an instance of any type.
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## Installation
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dependencies:
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belatuk_json_serializer: ^5.0.0
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## Usage
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It is recommended to import the library under an alias, i.e., `jsonSerializer`.
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```dart
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import 'package:belatuk_json_serialization/belatuk_json_serialization.dart' as jsonSerializer;
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```
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## Serializing JSON
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Simply call `jsonSerializer.serialize(x)` to synchronously transform an object into a JSON
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string.
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```dart
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Map map = {"foo": "bar", "numbers": [1, 2, {"three": 4}]};
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// Output: {"foo":"bar","numbers":[1,2,{"three":4]"}
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String json = jsonSerializer.serialize(map);
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print(json);
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```
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You can easily serialize classes, too. Belatuk JSON Serializer also supports classes as members.
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```dart
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class A {
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String foo;
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A(this.foo);
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}
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class B {
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late String hello;
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late A nested;
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B(String hello, String foo) {
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this.hello = hello;
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this.nested = A(foo);
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}
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}
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main() {
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print(jsonSerializer.serialize( B("world", "bar")));
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}
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// Output: {"hello":"world","nested":{"foo":"bar"}}
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```
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If a class has a `toJson` method, it will be called instead.
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## Deserializing JSON
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Deserialization is equally easy, and is provided through `jsonSerializer.deserialize`.
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```dart
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Map map = jsonSerializer.deserialize('{"hello":"world"}');
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int three = jsonSerializer.deserialize("3");
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```
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### Deserializing to Classes
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Belatuk JSON Serializer lets you deserialize JSON into an instance of any type. Simply pass the type as the second argument to `jsonSerializer.deserialize`.
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If the class has a `fromJson` constructor, it will be called instead.
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```dart
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class Child {
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String foo;
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}
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class Parent {
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String hello;
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Child child = Child();
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}
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main() {
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Parent parent = jsonSerializer.deserialize('{"hello":"world","child":{"foo":"bar"}}', Parent);
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print(parent);
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}
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```
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**Any JSON-deserializable classes must initializable without parameters. If `Foo()` would throw an error, then you can't use Foo with JSON.**
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This allows for validation of a sort, as only fields you have declared will be accepted.
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```dart
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class HasAnInt { int theInt; }
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HasAnInt invalid = jsonSerializer.deserialize('["some invalid input"]', HasAnInt);
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// Throws an error
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```
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An exception will be thrown if validation fails.
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