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Constant keys generator

A Flutter Dart library to generate a Dart file containing String constants representing the JSON path of a given JSON or YAML file. This tool helps developers manage JSON paths as constants in their Flutter projects.

Features

• Input File: Accepts JSON or YAML file as input.
• Output File: Generates a Dart file containing String constants for all paths in the input file.
• Ease of Use: Running with build_runner build command
• Flutter-Compatible: Perfect for Flutter projects needing structured JSON path management.

Install

Add the package to your pubspec.yaml:

flutter pub add --dev constant_keys_generator

Guide to generate files

1. Setup the configuration file

Create your own yaml setting file named constant_keys_generator.yaml in the root folder of your project

constant_keys_generator:
  # output_dir: The directory for output all generated files (inside lib directory)
  output_dir: "generated"

  # file_configs: List of files to generate
  #     Properties of each item:
  #         - input_file: file path, support glob path pattern (https://pub.dev/packages/glob)
  #         - output_file: name of output file without .g.dart extension
  file_configs:
    - input_file: "assets/translations/*.json"
      output_file: "locale_keys"

OR

Add your configuration into pubspec.yaml

2. Prepare the input files

Example: prepare 2 translation files inside assets/translations directory

en.json

{
    "common": {
        "appName": "Constant keys generator"
    }
}

vi.json

{
    "common": {
        "appName": "Trình tạo khóa cố định"
    }
}

3. Run the generator

To run the code generator, execute the following command:

dart run build_runner build

4. Verify the generated files

example/lib/generated/constant_keys/locale_keys.g.dart

// ignore_for_file: camel_case_types
class _LocaleKeys_Common {
  final String appName = 'common.appName';
  _LocaleKeys_Common();
}

class _LocaleKeys {
  final _LocaleKeys_Common common = _LocaleKeys_Common();
  _LocaleKeys();
}

// ignore: non_constant_identifier_names
final LocaleKeys = _LocaleKeys();

Generated files' usecase

When we developed an application using the easy_localization library, although this library provides a code generation mechanism, the results, whether in keys or json format, were not easy to use.

In keys format

// DO NOT EDIT. This is code generated via package:easy_localization/generate.dart

abstract class  LocaleKeys {
  static const common_appName = 'common.appName';
  static const common = 'common';

}

In json format

// DO NOT EDIT. This is code generated via package:easy_localization/generate.dart

// ignore_for_file: prefer_single_quotes, avoid_renaming_method_parameters

import 'dart:ui';

import 'package:easy_localization/easy_localization.dart' show AssetLoader;

class CodegenLoader extends AssetLoader{
  const CodegenLoader();

  @override
  Future<Map<String, dynamic>?> load(String path, Locale locale) {
    return Future.value(mapLocales[locale.toString()]);
  }

  static const Map<String,dynamic> ja = {
  "common": {
    "appName": "定数キージェネレータ"
  }
};
static const Map<String,dynamic> en = {
  "common": {
    "appName": "Constant keys generator"
  }
};
static const Map<String,dynamic> vi = {
  "common": {
    "appName": "Trình tạo khóa cố định"
  }
};
static const Map<String, Map<String,dynamic>> mapLocales = {"ja": ja, "en": en, "vi": vi};
}

Therefore, we developed this library as an alternative solution for generating type-safe keys for libraries like easy_localization.

Generated file from generator

// coverage:ignore-file
// GENERATED CODE - DO NOT MODIFY BY HAND

// *****************************************************
//  TKS Vietnam - constant_keys_generator
// *****************************************************

class _LocaleKeys_Common {
  final String appName = 'common.appName';
  _LocaleKeys_Common();
}

class _LocaleKeys {
  final _LocaleKeys_Common common = _LocaleKeys_Common();
  _LocaleKeys();
}

// ignore: non_constant_identifier_names
final LocaleKeys = _LocaleKeys();

And using with easy_localization

import 'package:easy_localization/easy_localization.dart';
import 'package:example/generated/constant_keys/locale_keys.dart';

Text(tr(LocaleKeys.common.appName))

or

import 'package:easy_localization/easy_localization.dart';
import 'package:example/generated/constant_keys/locale_keys.dart';

String appName = tr(LocaleKeys.common.appName))