6

According to the json_serializable package installing instructions, you should add the following dependency:

dependencies:
  json_serializable: ^2.0.3

This is my code:

import 'package:json_annotation/json_annotation.dart';

part 'person.g.dart';

@JsonSerializable(nullable: false)
class Person {
  final String firstName;
  final String lastName;
  final DateTime dateOfBirth;
  Person({this.firstName, this.lastName, this.dateOfBirth});
  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
  Map<String, dynamic> toJson() => _$PersonToJson(this);
}

Now running this in Flutter:

flutter packages pub run build_runner build

Or this for a Dart project:

pub run build_runner build

I get the following error:

Could not find package "build_runner". Did you forget to add a dependency?

What's wrong?

Suragch
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  • You forgot to install `build_runner` you can do it by using `pub global activate build_runner` to do it globally or like you mentioned in your answer. – Phani Rithvij Dec 28 '19 at 10:37

2 Answers2

18

This is a problem with how Pub is set up to automatically generate the installation instructions. Here are the dependencies that you actually need to add:

dependencies:
  json_annotation: ^2.0.0

dev_dependencies:
  build_runner: ^1.0.0
  json_serializable: ^2.0.0

This is shown in the json_serializable example.

Now you can generate the dart file for a class like this

import 'package:json_annotation/json_annotation.dart';

part 'person.g.dart';

@JsonSerializable(nullable: false)
class Person {
  final String firstName;
  final String lastName;
  final DateTime dateOfBirth;
  Person({this.firstName, this.lastName, this.dateOfBirth});
  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
  Map<String, dynamic> toJson() => _$PersonToJson(this);
}

by running this in a Flutter project:

flutter packages pub run build_runner build

or this in a Dart project:

pub run build_runner build

Other notes:

  • Make sure that part 'person.g.dart' matches the name of your person.dart model class file. That is, don't call it example.g.dart.
Suragch
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  • This worked for me. Is there any shortcut for that 'flutter packages pub run build_runner build' command in Android Studio by any chance? – Fran Marzoa Jun 14 '21 at 16:38
  • @FranMarzoa, I'm not sure. I used to use Android Studio for everything but I switched to VS Code and the command line more. Overall I prefer it. https://medium.com/flutter-community/moving-to-visual-studio-code-from-android-studio-a-guide-for-flutter-developers-8ce506406faf?sk=6c0843b0aadaff59fddb4945a11889e2 – Suragch Jun 15 '21 at 03:16
0

you need to run flutter packages get first

abdalmonem
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  • The problem wasn't that I hadn't gotten the packages, but that I hadn't included `build_runner` and `json_annotation` in the pubspec.yaml file. – Suragch Mar 25 '19 at 22:21