How to use the Hapi.js framework for building RESTful APIs in Node.js



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Hapi.js is a powerful and flexible framework for building web applications and RESTful APIs in Node.js. It is known for its configuration-centric approach and extensibility. Below are the steps to get started with building RESTful APIs using Hapi.js:

  1. Install Hapi.js: You can install Hapi.js using npm, the Node.js package manager. Open a terminal and run the following command:

    bash
    npm install hapi

  2. Create a new Hapi.js project: Create a new directory for your project and navigate into it:

    bash
    mkdir my-hapi-api
cd my-hapi-api

  3. Initialize your project: Run the following command to create a package.json file:

    bash
    npm init -y

  4. Create the main file (e.g., app.js): Create a new JavaScript file (e.g., app.js) to serve as the entry point for your Hapi.js application.

    javascript
    const Hapi = require('@hapi/hapi');

const init = async () => {
  const server = Hapi.server({
    port: 3000,
    host: 'localhost',
  });

  server.route({
    method: 'GET',
    path: '/',
    handler: (request, h) => {
      return 'Hello, Hapi!';
    },
  });

  await server.start();
  console.log('Server running on %s', server.info.uri);
};

process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});

init();

  5. Run your Hapi.js server: Execute the following command to start your Hapi.js server:

    bash
    node app.js

    You should see the message "Server running on http://localhost:3000" in the console.

  6. Define routes for your RESTful API: Expand your app.js file to include routes for your API. For example:

    javascript
    // ... (previous code)

server.route({
  method: 'GET',
  path: '/api/users',
  handler: (request, h) => {
    // Fetch and return a list of users
    return [
      { id: 1, name: 'John Doe' },
      { id: 2, name: 'Jane Doe' },
    ];
  },
});

// ... (additional routes)

// ...

  7. Handling request parameters: You can access request parameters using request.params or request.query:

    javascript
    server.route({
  method: 'GET',
  path: '/api/users/{userId}',
  handler: (request, h) => {
    const userId = request.params.userId;
    // Fetch and return user details for the specified userId
  },
});

    Additionally, you can use request payload for POST requests:

    javascript
    server.route({
  method: 'POST',
  path: '/api/users',
  handler: (request, h) => {
    const newUser = request.payload;
    // Process and save the new user
  },
});

  8. Middleware and plugins: Hapi.js allows you to use middleware and plugins for additional functionality. You can use server.ext to add extensions:

    javascript
    server.ext('onRequest', (request, h) => {
  // Your middleware logic here
  return h.continue;
});

  9. Validation and Joi: Hapi.js integrates with the Joi validation library. You can use Joi to validate request payloads, parameters, and query parameters:

    javascript
    const Joi = require('joi');

server.route({
  method: 'POST',
  path: '/api/users',
  handler: (request, h) => {
    const newUser = request.payload;
    // Process and save the new user
    return 'User created successfully';
  },
  options: {
    validate: {
      payload: Joi.object({
        name: Joi.string().required(),
        email: Joi.string().email().required(),
      }),
    },
  },
});

  10. Handle errors: You can handle errors by returning a Boom response or throwing an error within your route handler:

    javascript
    server.route({
  method: 'GET',
  path: '/api/error',
  handler: (request, h) => {
    // Example of handling an error
    const error = Boom.badRequest('Custom error message');
    throw error;
  },
});

These steps should help you get started with building RESTful APIs using Hapi.js. Remember to refer to the official Hapi.js documentation for more detailed information on features and configuration options.

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