**Course Title:** Mastering Node.js: Building Scalable Web Applications **Section Title:** Building RESTful APIs **Topic:** Develop a fully functional RESTful API for a task management system with validation and error handling.(Lab topic) **Objective:** By the end of this topic, you will be able to design and implement a fully functional RESTful API for a task management system using Node.js and Express.js, with proper validation and error handling. **Prerequisites:** * Basic understanding of Node.js, Express.js, and MongoDB * Familiarity with RESTful API principles and CRUD operations * Knowledge of validation and error handling techniques **Task Management System API Requirements:** * Create tasks * Read tasks * Update tasks * Delete tasks * Get all tasks * Get tasks by user ID **API Endpoints:** * **POST /tasks**: Create a new task * **GET /tasks**: Get all tasks * **GET /tasks/:id**: Get a task by ID * **PUT /tasks/:id**: Update a task * **DELETE /tasks/:id**: Delete a task * **GET /tasks/user/:id**: Get tasks by user ID **Validation and Error Handling:** * Validate task creation and update requests using Joi or express-validator * Handle errors using a custom error handler middleware * Return errors in a standardized format (e.g., JSON with error code and message) **Implementation:** 1. **Task Model:** Define a Task model using Mongoose, with fields for task name, description, and user ID. 2. **Task Service:** Create a Task service that encapsulates business logic for task creation, reading, updating, and deletion. 3. **API Endpoints:** Implement API endpoints using Express.js, using the Task service to perform CRUD operations. 4. **Validation and Error Handling:** Implement validation and error handling using Joi or express-validator, and a custom error handler middleware. **Example Code:** ```javascript // task.model.js const mongoose = require('mongoose'); const taskSchema = new mongoose.Schema({ name: String, description: String, userId: String }); const Task = mongoose.model('Task', taskSchema); module.exports = Task; ``` ```javascript // task.service.js const Task = require('./task.model'); const createTask = async (task) => { const newTask = new Task(task); await newTask.save(); return newTask; }; const getTasks = async () => { return Task.find().exec(); }; const getTaskById = async (id) => { return Task.findById(id).exec(); }; const updateTask = async (id, task) => { return Task.findByIdAndUpdate(id, task, { new: true }).exec(); }; const deleteTask = async (id) => { return Task.findByIdAndRemove(id).exec(); }; module.exports = { createTask, getTasks, getTaskById, updateTask, deleteTask }; ``` ```javascript // task.controller.js const express = require('express'); const router = express.Router(); const taskService = require('./task.service'); router.post('/', async (req, res) => { try { const task = await taskService.createTask(req.body); res.json(task); } catch (error) { res.status(400).json({ error: 'Invalid request' }); } }); router.get('/', async (req, res) => { try { const tasks = await taskService.getTasks(); res.json(tasks); } catch (error) { res.status(500).json({ error: 'Internal server error' }); } }); router.get('/:id', async (req, res) => { try { const task = await taskService.getTaskById(req.params.id); if (!task) { res.status(404).json({ error: 'Task not found' }); } else { res.json(task); } } catch (error) { res.status(500).json({ error: 'Internal server error' }); } }); router.put('/:id', async (req, res) => { try { const task = await taskService.updateTask(req.params.id, req.body); res.json(task); } catch (error) { res.status(400).json({ error: 'Invalid request' }); } }); router.delete('/:id', async (req, res) => { try { await taskService.deleteTask(req.params.id); res.json({ message: 'Task deleted successfully' }); } catch (error) { res.status(500).json({ error: 'Internal server error' }); } }); module.exports = router; ``` **Validation and Error Handling:** ```javascript // validation.js const Joi = require('joi'); const taskSchema = Joi.object().keys({ name: Joi.string().required(), description: Joi.string().required(), userId: Joi.string().required() }); module.exports = { validateTask: (task) => { return Joi.validate(task, taskSchema); } }; ``` ```javascript // error-handler.js const express = require('express'); const router = express.Router(); router.use((error, req, res, next) => { res.status(500).json({ error: 'Internal server error' }); }); module.exports = router; ``` **API Documentation:** You can use tools like Swagger or API Blueprint to generate API documentation. **Commit Messages:** * `feat: add task model` * `feat: add task service` * `feat: add API endpoints` * `feat: add validation and error handling` * `docs: update API documentation` **API Endpoints:** * `POST /tasks`: Create a new task * `GET /tasks`: Get all tasks * `GET /tasks/:id`: Get a task by ID * `PUT /tasks/:id`: Update a task * `DELETE /tasks/:id`: Delete a task * `GET /tasks/user/:id`: Get tasks by user ID **API Request Body:** * `name`: Task name * `description`: Task description * `userId`: User ID **API Response:** * `200 OK`: Task created successfully * `404 Not Found`: Task not found * `500 Internal Server Error`: Internal server error **API Validation:** * `name`: Required * `description`: Required * `userId`: Required **API Error Handling:** * `400 Bad Request`: Invalid request * `500 Internal Server Error`: Internal server error This is a basic example of how you can implement a fully functional RESTful API for a task management system using Node.js and Express.js, with proper validation and error handling. You can customize and extend this example to fit your specific needs. **Leave a comment or ask for help if you have any questions or need further clarification on any of the topics covered in this topic.** **Next topic:** Understanding user authentication strategies (session-based vs. token-based). From: Authentication and Authorization.