model_guard 0.0.9

Automatic JSON parser for Flutter/Dart that logs model name, field name, and wrong values during parsing.

model_guard model_guard is a lightweight Dart/Flutter utility that safely parses JSON responses and logs useful debugging information when parsing fails.

It helps developers detect incorrect API responses without crashing the application.

✨ Features

Automatically logs parsing errors

Shows model name + field name + invalid value

Works with single objects and lists

Prevents crashes from invalid JSON

Works with any API client

Compatible with Flutter and Dart

📦 Installation

Add the dependency to your pubspec.yaml:

yaml
  dependencies:
     model_guard: ^0.0.2

Then run:

 bash
   flutter pub get

🚀 Usage

1. Define your model

   import 'package:model_guard/guard_model.dart';

     class Product implements GuardModel {
     final int id;
     final String title;
     final double price;
   
    Product({
      required this.id,
      required this.title,
      required this.price,
    });
   
   factory Product.fromJson(Map<String, dynamic> json) {
    return Product(
       id: json['id'] ?? 0,
       title: json['title'] ?? '',
       price: (json['price'] ?? 0).toDouble(),
    );
    }
   
    @override
    GuardModel fromJson(Map<String, dynamic> json) => Product.fromJson(json);
    }
   

2. Wrap your API client

       import 'package:model_guard/api_wrapper.dart';
    import 'product.dart';
   
    final api = ApiWrapper<Product>(
    apiClient: myApiClient, // your API client
    modelName: "Product",
    fromJson: (json) => Product.fromJson(json),
    );
   
    // Fetch single object
    final product = await api.get("/product");
   
    // Fetch list of objects
    final products = await api.getList("/products");
    Note: Invalid fields are automatically logged to the console. Invalid items in a list are skipped, so your app doesn't crash.
   

📝 Example API Client (for testing)

	class FakeApiClient {
		Future<Map<String, dynamic>> get(String url) async {
		return {"id": 1, "title": "iPhone", "price": 999};
	}

	Future<List<dynamic>> getList(String url) async {
	return [
		{"id": 1, "title": "iPhone", "price": 999},
		{"id": 2, "title": "Laptop", "price": "wrong_type"} // invalid
	];
	}
}

📋 SafeParser Logs Example When parsing fails, your console will show:

	text
	[ModelGuard] Product.price = wrong_type (invalid type)

📱 Flutter Widget Example

	import 'package:flutter/material.dart';
	import 'package:model_guard/api_wrapper.dart';
	import 'product.dart';

	class ExampleWidget extends StatefulWidget {
		const ExampleWidget({super.key});

		@override
		State<ExampleWidget> createState() => _ExampleWidgetState();
	}

	class _ExampleWidgetState extends State<ExampleWidget> {
	List<Product> products = [];

	@override
	void initState() {
	super.initState();
	fetchProducts();
	}

	void fetchProducts() async {
	final client = FakeApiClient();
	final api = ApiWrapper<Product>(
	apiClient: client,
	modelName: "Product",
	fromJson: (json) => Product.fromJson(json),
	);

final result = await api.getList("/products");
setState(() {
  products = result;
});
}

	@override
	Widget build(BuildContext context) {
	if (products.isEmpty) {
	return const Center(child: CircularProgressIndicator());
	}

return ListView.builder(
  itemCount: products.length,
  itemBuilder: (context, index) {
    final p = products[index];
    return ListTile(
      title: Text(p.title),
      subtitle: Text("Price: \$${p.price}"),
    );
  },
);
}
}

// Fake API Client for demo

	class FakeApiClient {
	Future<Map<String, dynamic>> get(String url) async {
	return {"id": 1, "title": "iPhone", "price": 999};
	}

	Future<List<dynamic>> getList(String url) async {
	return [
	{"id": 1, "title": "iPhone", "price": 999},
	{"id": 2, "title": "Laptop", "price": "wrong_type"} // invalid
	];
	}
	}

📄 License This project is licensed under the MIT License.