Introduction to JSON annotations

Installing and Using json_serializable and json_annotation packages

Add this to your package's pubspec.yaml file:

# pubspec.yaml
dependencies:
  json_annotation: ^4.0.0

dev_dependencies:
  build_runner:
  json_serializable 4.0.2

You can then install packages from the command line:

$ dart pub get

Alternatively, your editor might support dart pub get. Check the docs for your editor to learn more.

Example

Now you can use it in your Dart code by importing it like this:

import 'package:json_annotation/json_annotation.dart';

part 'my_model.g.dart';

Note that the line partmy_demo.g.dartwill give you a warning, because the file is not created yet

Write the following code

import 'package:json_annotation/json_annotation.dart';

part 'my_model.g.dart';

@freezed
class Person with _$Person {
  const factory Person({
    @required String firstName,
    @required String lastName,
  }) = _Person;

  factory Person.fromJson(Map<String, dynamic> json) =>
      _$PersonFromJson(json);
}

To generate the code type the following command

$ flutter pub run build_runner build

Ignore lint warnings on generated files

It is likely that the code generated by Json_Serializer will cause your linter to report warnings.

The solution to this problem is to tell the linter to ignore generated files, by modifying your analysis_options.yaml:

analyzer:
  exclude:
    - "**/*.g.dart"