dart_json_annotations library

High-performance code generation for Dart/Flutter models.

Generates JSON serialization, copyWith, equatable, and union methods using a Rust-powered CLI for maximum speed.

Quick Start

import 'package:dart_json_annotations/dart_json_annotations.dart';

@Model()  // JSON only (default)
class User {
  final String name;
  final int age;
  User({required this.name, required this.age});
}

Model Presets

Preset	Features	Lines/Model
@Model.json()	JSON only	~25
@Model.data()	JSON + copyWith + equatable	~50
@Model.bloc()	copyWith + equatable (no JSON)	~35
@Model.mutable()	copyWith (always)	~40

Classes

Assert

Adds validation assertion for a field.

Default

Sets a default value for a field.

GenericConfig

Mutable class annotation (equivalent to Freezed's @unfreezed).

Ignore

Ignore this field from specific features.

Implements<T>

Implements an interface for a union variant.

JsonConverter

Custom JSON converter for a field.

JsonEnum

Marks an enum for JSON serialization with custom value mapping.

JsonKey

Customizes JSON serialization for a specific field.

JsonType

Sets the naming convention for JSON field serialization.

JsonValue

Custom JSON value for enum variants.

Model

Unified model annotation with feature flags.

ModelUnionValue

Custom discriminator value for a union variant.

With<T>

Mixes in a class for a union variant.

Enums

JsonEnumValue

NamingConvention

Defines the naming convention for JSON serialization.