Jaguar Web Framework

Introduction to Jaguar Dart Framework

Jaguar is a powerful and flexible web framework for building server-side applications using the Dart programming language. It provides a wide range of features and tools that make it easy to develop high-performance web applications. In this tutorial, we will explore the history, features, and examples of the Jaguar Dart Framework.

History

Jaguar was initially developed by Kasper Lund, a software engineer at Google. The framework was inspired by other popular web frameworks such as Express.js and Ruby on Rails. It was created to provide a simple and efficient way to build web applications in Dart.

Features

1. Routing

Jaguar provides a flexible and intuitive routing system that allows you to define routes and handle HTTP requests easily. Here is an example of how to define a route and handle a GET request:

import 'package:jaguar/jaguar.dart';

void main() {
  final app = Jaguar();
  
  app.get('/hello', (Context ctx) => 'Hello, World!');
  
  app.log.onRecord.listen(print);
  app.serve();
}

In the above example, we define a route /hello and specify a handler function that returns a simple "Hello, World!" message. The app.get method is used to handle GET requests.

2. Middleware

Jaguar supports middleware, which allows you to modify and intercept requests and responses. Middleware functions can be used for tasks such as authentication, logging, and error handling. Here is an example of how to use middleware in Jaguar:

import 'package:jaguar/jaguar.dart';

void main() {
  final app = Jaguar();
  
  app.use((Context ctx) {
    ctx.response.headers['Content-Type'] = 'application/json';
  });
  
  app.get('/hello', (Context ctx) => 'Hello, World!');
  
  app.log.onRecord.listen(print);
  app.serve();
}

In the above example, we define a middleware function using the app.use method. This function sets the Content-Type header to application/json for all requests. The app.get method is used to handle the /hello route.

3. Dependency Injection

Jaguar has built-in support for dependency injection, which allows you to easily manage and inject dependencies into your application. This promotes modular and testable code. Here is an example of how to use dependency injection in Jaguar:

import 'package:jaguar/jaguar.dart';

class UserService {
  String getUser() => 'John Doe';
}

void main() {
  final app = Jaguar();
  
  app.inject(UserService());
  
  app.get('/user', (Context ctx, UserService userService) {
    return 'User: ${userService.getUser()}';
  });
  
  app.log.onRecord.listen(print);
  app.serve();
}

In the above example, we define a UserService class and inject an instance of it using the app.inject method. The app.get method now takes an additional parameter of type UserService, which allows us to access and use the injected dependency.

4. WebSocket Support

Jaguar provides built-in support for WebSocket communication, allowing you to build real-time applications. Here is an example of how to use WebSockets in Jaguar:

import 'package:jaguar/jaguar.dart';

void main() {
  final app = Jaguar();
  
  app.ws('/chat', (Context ctx) async {
    final socket = await ctx.ws();
    
    socket.listen((data) {
      socket.add('Received: $data');
    });
  });
  
  app.log.onRecord.listen(print);
  app.serve();
}

In the above example, we define a WebSocket route /chat using the app.ws method. Inside the handler function, we await the WebSocket connection using ctx.ws() and then listen for incoming messages. Any message received is sent back to the client using socket.add.

Examples

Here are a few more examples that demonstrate the power and flexibility of the Jaguar Dart Framework:

1. Jaguar Todo App: A simple todo application built using Jaguar.

2. Jaguar Chat App: A real-time chat application using WebSockets in Jaguar.

3. Jaguar GraphQL Example: An example of integrating GraphQL with Jaguar.

4. Jaguar File Upload Example: Demonstrates how to handle file uploads in Jaguar.

Conclusion

Jaguar is a powerful and feature-rich web framework for building server-side applications in Dart. It provides a wide range of features such as routing, middleware, dependency injection, and WebSocket support. The examples provided in this tutorial should give you a good starting point for exploring and utilizing the capabilities of the Jaguar Dart Framework.

For more information and detailed documentation, please visit the official Jaguar website.