data_classes 1.0.2

Automatically generates immutable data classes for you based on a mutable "blueprint" class.

Hey there! If you're reading this and want data classes to become a language-level feature of Dart, consider giving this issue a thumbs up.

In the meantime, this library generates immutable data classes for you based on simple mutable blueprint classes.

Simply add it to your dependencies like this:

dependencies:
  data_classes: ^1.0.2

dev_dependencies:
  data_classes_generator: ^1.0.1

Then, you can write data classes by letting their name start with Mutable and annotating them with @DataClass(), like this:

import 'package:data_classes/data_classes.dart';

part 'my_file.g.dart';

@DataClass()
class MutableUser {
  String firstName;
  String lastName;
  @Nullable() String photoUrl;
}

By default, attributes are considered non-nullable. If you want an attribute to be nullable, annotate it with @Nullable().

By running pub run build_runner build in the command line (or flutter pub run build_runner build, if you're using Flutter), the implementation based on your mutable class is automatically generated.

The immutable class contains

• a constructor with named parameters and assertion for values that shouldn't be [null],
• serialization method/constructor for converting the immutable class to the the mutable class and the other way around,
• custom implementations of == and hashCode,
• a copyWith function.

For example, here's the generated code of our 6-line-class above:

/// This class is the immutable data class pendant of the MutableUser class.
@immutable
class User {
  final String firstName;
  final String lastName;
  final String photoUrl;

  /// Default constructor that creates a User.
  const User({
    @required this.firstName,
    @required this.lastName,
    this.photoUrl,
  })  : assert(firstName != null),
        assert(lastName != null);

  /// Creates a User from a MutableUser.
  factory User.fromMutable($User mutable) {
    return User(
      firstName: mutable.firstName,
      lastName: mutable.lastName,
      photoUrl: mutable.photoUrl,
    );
  }

  /// Turns this User into a MutableUser.
  $User toMutable() {
    return $User()
      ..firstName = firstName
      ..lastName = lastName
      ..photoUrl = photoUrl;
  }

  /// Checks if this User is equal to the other one.
  bool operator ==(Object other) {
    return other is User &&
        firstName == other.firstName &&
        lastName == other.lastName &&
        photoUrl == other.photoUrl;
  }

  int get hashCode => hashList([
      firstName,
      lastName,
      photoUrl,
    ]);

  User copyWith({
    String firstName,
    String lastName,
    String photoUrl,
  }) {
    return User(
      firstName: firstName ?? this.firstName,
      lastName: lastName ?? this.lastName,
      photoUrl: photoUrl ?? this.photoUrl,
    );
  }
}