Dart Class Generator from JSON

This tool allows you to generate Dart classes from JSON files. It helps in converting a given JSON structure into a Dart class with fields, constructors, and toJson and fromJson methods. The generated classes are written to the lib/generated directory.

Features

  • Automatically generates Dart classes from a JSON file.
  • Supports nested JSON structures by creating appropriate imports and nested classes.
  • Creates fromJson and toJson methods for easy serialization and deserialization.

Requirements

  • Dart SDK installed.

Usage

After adding this package as a dependency in your project, you can run the command like this:

dart run dartify_json -i <path_to_your_json_file> -c User
  • -i or --input: Path to the JSON file.
  • -c or --className: Class name for the generated Dart class.

Example

Suppose you have the following JSON file address.json:

{
  "street": "123 Main St",
  "city": "Metropolis",
  "country": {
    "name": "Wonderland",
    "code": "WL"
  }
}

To generate a Dart class from this JSON file, run:

dart run dartify_json -i address.json -c Address

The generated file will be saved in lib/generated/address.dart and will look like this:

import 'country.dart';

class Address {
  final String street;
  final String city;
  final Country country;

  Address({
    required this.street,
    required this.city,
    required this.country,
  });

  factory Address.fromJson(Map<String, dynamic> json) {
    return Address(
      street: json['street'],
      city: json['city'],
      country: Country.fromJson(json['country']),
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'street': street,
      'city': city,
      'country': country.toJson(),
    };
  }
}

Additionally, if the JSON contains nested objects (e.g., country), the script will generate corresponding classes for those nested objects as well.

Directory Structure

The generated files are placed in the lib/generated directory. If the directory does not exist, it will be created automatically.

Example Directory Structure

project_root/
  ├── lib/
  │   ├── generated/
  │   │   ├── address.dart
  │   │   └── country.dart
  └── main.dart

How It Works

  1. Parsing JSON: The script takes a JSON file as input and parses it using dart:convert.
  2. Generating Fields: The keys in the JSON object are used to create fields in the Dart class, and their types are inferred.
  3. Generating Methods: The fromJson and toJson methods are generated for easy serialization and deserialization.
  4. Handling Nested Objects: For nested JSON objects, additional Dart classes are generated and appropriate imports are added to the main class file.

Using Generated Classes in an API

To use the generated Dart files in your API, follow these steps:

1. Import the Generated Classes

First, import the generated classes into the files where you'll be using them to handle API data.

For example, if you've generated a User class, you would import it like this:

import 'generated/user.dart';

2. Use the fromJson and toJson Methods

The generated classes come with fromJson and toJson methods that make it easy to work with JSON data from your API.

  • Receiving API Data: When you receive data from an API (e.g., via an HTTP GET request), you can parse the JSON and use the fromJson method to convert it into a Dart object.

    Example:

    import 'dart:convert';
import 'package:http/http.dart' as http;
import 'generated/user.dart';

Future<User> fetchUser(String userId) async {
  final response = await http.get(Uri.parse('https://api.example.com/users/$userId'));

  if (response.statusCode == 200) {
    // Convert JSON response to a User object
    return User.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to load user');
  }
}

  • Sending API Data: When you need to send data to an API (e.g., via an HTTP POST request), you can use the toJson method to convert your Dart object to a JSON map.

    Example:

    import 'dart:convert';
import 'package:http/http.dart' as http;
import 'generated/user.dart';

Future<void> createUser(User user) async {
  final response = await http.post(
    Uri.parse('https://api.example.com/users'),
    headers: <String, String>{
      'Content-Type': 'application/json; charset=UTF-8',
    },
    body: jsonEncode(user.toJson()),
  );

  if (response.statusCode != 201) {
    throw Exception('Failed to create user');
  }
}

3. Handling Nested JSON Structures

If your API returns nested JSON structures, you can use the generated classes for nested objects as well.

For example, if your User object contains an Address field, you can use the Address class that was also generated:

import 'generated/user.dart';
import 'generated/address.dart';

void main() {
  final address = Address(street: '123 Main St', city: 'Metropolis', country: Country(name: 'Wonderland', code: 'WL'));
  final user = User(id: 1, name: 'John Doe', address: address);

  // Convert to JSON for API usage
  print(user.toJson());
}

Notes

  • The script supports primitive types (int, double, bool, String) as well as nested objects and lists.
  • If the JSON structure changes, you need to regenerate the Dart classes to reflect the changes.

Troubleshooting

  • If you see an error like Input file not found, make sure the JSON file path is correct.
  • For nested JSON objects, make sure that the generated files are correctly imported in the respective classes.

Contributions

Feel free to contribute by opening issues or pull requests if you have suggestions or find bugs.

Libraries

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