json_data_loader 1.0.2

A lightweight JSON loader for Flutter apps. Load JSON from assets or network and map it to your models.

json_data_loader

A lightweight and flexible JSON loader for Flutter apps.
Load JSON from local assets or network APIs and map it directly to your Dart models.

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Features

• Load JSON from assets (local files) or network (HTTP URLs)
• Map JSON to any Dart model via fromJson function
• Supports List and Map JSON structures
• No caching — always fetch fresh data
• Uses compute() to parse large JSON without blocking the UI
• Flutter compatible (uses rootBundle for assets)
• Easy integration in any Flutter project

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Installation

Add the dependency in your pubspec.yaml:

dependencies:
  json_data_loader: ^1.0.0

Then run:

flutter pub get

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Quick Start / Usage

1️⃣ Load a list of models from a local asset

import 'package:json_data_loader/json_data_loader.dart';
import 'posts_model.dart';

final posts = await JsonDataLoader.loadList<PostsModel>(
  source: JsonSource.asset('assets/posts.json'),
  fromJson: (json) => PostsModel.fromJson(json),
);

2️⃣ Load a list of models from a network API

final posts = await JsonDataLoader.loadList<PostsModel>(
  source: JsonSource.network('https://jsonplaceholder.typicode.com/posts'),
  fromJson: (json) => PostsModel.fromJson(json),
);

3️⃣ Load a single object from JSON

final user = await JsonDataLoader.loadObject<UserModel>(
  source: JsonSource.network('https://example.com/user/1'),
  fromJson: (json) => UserModel.fromJson(json),
);

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Example Flutter Widget

class PostsPage extends StatelessWidget {
  const PostsPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Posts')),
      body: FutureBuilder<List<PostsModel>>(
        future: JsonDataLoader.loadList<PostsModel>(
          source: JsonSource.network(
              'https://jsonplaceholder.typicode.com/posts'),
          fromJson: (json) => PostsModel.fromJson(json),
        ),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          } else if (snapshot.hasError) {
            return Center(child: Text('Error: ${snapshot.error}'));
          } else if (!snapshot.hasData || snapshot.data!.isEmpty) {
            return const Center(child: Text('No data'));
          }

          final posts = snapshot.data!;
          return ListView.builder(
            itemCount: posts.length,
            itemBuilder: (context, i) {
              final post = posts[i];
              return ListTile(
                title: Text(post.title),
                subtitle: Text(post.body),
              );
            },
          );
        },
      ),
    );
  }
}

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Model Example

class PostsModel {
  final int userId;
  final int id;
  final String title;
  final String body;

  PostsModel({
    required this.userId,
    required this.id,
    required this.title,
    required this.body,
  });

  factory PostsModel.fromJson(Map<String, dynamic> json) => PostsModel(
        userId: json["userId"],
        id: json["id"],
        title: json["title"],
        body: json["body"],
      );
}

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Example Folder

You can check a full working example in the example/ folder of this package.
It demonstrates how to load JSON from both assets and network.

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Notes

• Ensure your JSON structure matches the model you are mapping.
• Large JSON files are parsed using compute() to avoid UI blocking.
• No caching: every call fetches fresh data from the source.
• Works with both List<dynamic> and Map<String, dynamic> JSON structures.

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Contributing

Contributions are welcome!
Fork the repository and submit pull requests for improvements or bug fixes.

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License

This project is licensed under the MIT License.