The purpose of this library is to expose the generation of very simple class methods with excellent performance and little code generation. For this you will only be able to enable what you need of the supported features

Features

Auto generation of:

• x Inheritance and generic classes supported
• x hashCode and == methods
• x pretty toString method
• x copyWith method with support a null values
• x *Changes class to updated your data class
• x *Builder class to build or update your data class

Install package

To use DataClass, you will need your typical build_runner/code-generator setup. First, install build_runner, data_class, data_class_generator by adding them to your pubspec.yaml file:

# pubspec.yaml
dependencies:
  mek_data_class:

dev_dependencies:
  build_runner:
  mek_data_class_generator:

Run the generator

To run the code generator you can use:

• <dart|flutter> pub run build_runner build

As such, a file that wants to use DataClass will start with:

import 'package:mek_data_class/mek_data_class.dart';

part 'my_file.g.dart';

Usage/Examples

You can see some examples in

• basic
• generics
• inheritance

Basic

Because the boiler plate is generated as a mixin, it is minimally intrusive on the interface of the class. You only have to provide a constructor with positional or named arguments for all fields and extend the generated mixin.

@DataClass()
class Product with _$Product {
  final String title;
  final double price;

  const Product({
    required this.title,
    required this.price,
  });
}

Customization of the equal operator and hashcode through the use of the Equality class is supported. See example.

Inheritance

Taking into consideration the previous example you can write and inherit all methods

@DataClass()
class PrettyProduct extends Product with _$PrettyProduct {
  final String color;

  const Product({
    required super.title,
    required super.price,
    required this.color,
  });

  String get titlePriceColor => '$titlePrice$color';
}

Generics

You can also declare classes with generic types

@DataClass()
class Value<T> with _$Value<T> {
  final T value;

  const Product({
    required this.value,
  });
}

Pretty string

Use the ClassToString package to perform the toString method

final product = Product(...);
/// Product(
///   title: "Overlord",
///   price: 12,
/// )
print(product);

CopyWith

The classic copyWith, need explanations? No, but it also supports null values!

final product = Product(...);
print(product.copyWith(title: 'Raisekamika'));

Enable in DataClass annotation or build.yaml file with copyable: true

*Changes

Unlike a builder you cannot set values to null but the field is not defined as such and cannot be instantiated

final updatedProduct = product.change((changes) => changes..title = 'Raisekamika');

final changes = product.toChanges();
changes.title = 'Raisekamika';
final updatedProduct = changes.build();

Enable in DataClass annotation or build.yaml file with changeable: true

*Changes.update

Update the *Changes class by passing a function

final updatedChanges = changes.update((c) => c..title = 'Albedo'); // title=Albedo

*Changes.replace

Update the properties of the *Changes class with the properties of the DataClass

final updatedChanges = productChanges.replace(product); // title=Raisekamika

*Changes.build

Build the DataClass from *Changes class

Product product = productChanges.build();

*Builder

Build your class using a builder. It is not safe to construct a class using a builder but it allows you to complete the construction whenever you want.

@DataClass(buildable: true)
class Product with _$Product {
  final int id;
  const Product({required this.id});
  factory Product.build(void Function(ProductBuilder b) updates) => 
          (ProductBuilder().update(updates)).build();
}

final builder = ProductBuilder();
builder.id = 12;
final product = builder.build();

Global Configs

See the docs of the DataClass class for more information

# build.yaml
targets:
  $default:
    builders:
      mek_data_class_generator:
        enabled: true
        options:
          equatable: true
          stringify: true
          stringify_if_null: true # if set to `false`, null values will not be included in the toString 
          buildable: false
          copyable: false
          changeable: false

Motivations

• Some packages generate a lot of code and mess with the normal, classic class construction in dart. Also you can't easily select classes without any problem, without having to create mixins for the methods
• Some packages require you to mark all your fields with @override

Similar packages freezed, built_value, dataclass_beta, functional_data