json-to-freezed-model

name	json_to_freezed_model
description	Parse JSON and create freezed object classes following project conventions.
conversation_mode	Fast

JSON to Freezed Object Skill

Parse JSON and generate freezed object classes in the data layer.

[!IMPORTANT] Execute Immediately: When this skill is requested, skip the PLANNING phase and implementation_plan.md creation. Proceed directly to EXECUTION.

[!IMPORTANT] Import Convention: Always use full package paths (e.g., import 'package:bloc_digital_wallet/core/network/app_uri.dart';) instead of relative imports (e.g., import '../../core/network/app_uri.dart';).

[!IMPORTANT] Always use abstract class for Freezed models

[!IMPORTANT] Always include private constructor: const ClassName._();

1. Analyze JSON Structure

1. Identify root object and nested objects
2. Map types: string → String?, number → int?/double?, boolean → bool?, object → nested object
3. Note snake_case keys that need @JsonKey mapping
4. Naming: Add Object suffix to nested object class names (e.g., user → UserObject). Do not add prefix for nested json object.

2. Create Model Files

[!CRITICAL] ONE OBJECT, ONE FILE RULE

Each class (Root or Nested) MUST have its own dedicated .dart file.

• ❌ NEVER define multiple classes in a single file
• ❌ NEVER put nested objects in the same file as the parent
• ✅ ALWAYS create a separate file for each object, even if it's small

Example: If JSON has user and address objects, create:

• user_object.dart (contains only UserObject)
• address_object.dart (contains only AddressObject)

For each object in the JSON hierarchy, create a separated file in the target data layer:

lib/features/{module}/data/models/
├── {root_object}.dart
├── {nested_object_1}.dart
└── {nested_object_2}.dart

3. Model Template

// Copyright (c) 2026, one of DanhDue ExOICTIF projects. All rights reserved.

// coverage:ignore-file
// ignore_for_file: invalid_annotation_target

import 'package:flutter/foundation.dart';
import 'package:freezed_annotation/freezed_annotation.dart';

// Import nested models if any
import 'package:bloc_digital_wallet/features/{module}/data/models/nested_object.dart';

part '{model_name}.freezed.dart';
part '{model_name}.g.dart';

@freezed
abstract class {ModelName} with _${ModelName} {
  const {ModelName}._();

  @JsonSerializable(includeIfNull: false)
  const factory {ModelName}({
    @JsonKey(name: 'field_name') String? fieldName,
    @JsonKey(name: 'count') int? count,
    @JsonKey(name: 'snake_case_field') String? camelCaseField,
    @JsonKey(name: 'nested') NestedObject? nested,
  }) = _{ModelName};

  factory {ModelName}.fromJson(Map<String, Object?> json) =>
      _${ModelName}FromJson(json);
}

4. Key Rules

JSON	Dart	Notes
snake_case key	camelCase property	Use @JsonKey(name: 'snake_case')
Same name	Same name	Always use @JsonKey(name: 'field_name')
Nested object	{Name}Object class	Auto-add Object suffix. No prefix.
All fields	Nullable (?)	Use int?, String?, etc.
Class	abstract class	Always use abstract class for Freezed models
includeIfNull	false	Always use @JsonSerializable(includeIfNull: false)
Constructor	const Class._();	Always include private constructor
Imports	foundation.dart + freezed_annotation	Both required for debugFillProperties support

Important: Always add @JsonKey annotation for every field, even when the JSON key matches the Dart property name exactly.

5. Example

Input JSON:

{
  "refresh": "token123",
  "access": "token456",
  "user": {
    "id": 1,
    "username": "john"
  }
}

Output:

user_object.dart:

@freezed
abstract class UserObject with _$UserObject {
  const UserObject._();

  const factory UserObject({
    @JsonKey(name: 'id') int? id,
    @JsonKey(name: 'username') String? username,
  }) = _UserObject;

  factory UserObject.fromJson(Map<String, Object?> json) =>
      _$UserObjectFromJson(json);
}

sign_in_object.dart:

@freezed
abstract class SignInObject with _$SignInObject {
  const SignInObject._();

  const factory SignInObject({
    @JsonKey(name: 'refresh') String? refresh,
    @JsonKey(name: 'access') String? access,
    @JsonKey(name: 'user') UserObject? user,
  }) = _SignInObject;

  factory SignInObject.fromJson(Map<String, Object?> json) =>
      _$SignInObjectFromJson(json);
}

6. After Creation

# Generate code
melos genAlls

# Verify
fvm flutter analyze --no-fatal-infos