Express: Task Management

Create an Express.js application to simulate a simple task management system. Each task should have an id, title, description, and a status field (e.g., “pending”, “in-progress”, “completed”). Initialize the application with at least two tasks in an in-memory array. The application must implement the following functionality using appropriate HTTP methods:

• GET /tasks: Return the list of all tasks.

• GET /tasks/:id: Return details of a task by its ID.

• POST /tasks: Accept a new task's title and description from the request body, assign a unique ID, default the status to “pending”, and add it to the array.

• PUT /tasks/:id: Allow the user to update any of the task fields (title, description, or status). Only the provided fields should be updated.

• DELETE /tasks/:id: Remove a task by its ID. If the task doesn't exist, return a 404 error.

• Ensure use of express.json() middleware for parsing input and res.send() for all output messages.

app.js

import express from 'express';

const app = express();
const PORT = 3000;

// Middleware to parse JSON bodies
app.use(express.json());

// In-memory data store for tasks
let tasks = [
    { id: 1, title: 'Setup Project', description: 'Initialize the project repository and install dependencies.', status: 'completed' },
    { id: 2, title: 'Develop API', description: 'Create the required API endpoints for the application.', status: 'in-progress' }
];

// Variable to manage the next unique ID
let nextId = 3;

// --- Routes ---

// GET /tasks - Retrieve all tasks
app.get('/tasks', (req, res) => {
    const responseText = tasks.map(t => `ID: ${t.id}, Title: ${t.title}, Status: ${t.status}`).join('\n');
    res.status(200).send(responseText);
});

// GET /tasks/:id - Retrieve a single task by its ID
app.get('/tasks/:id', (req, res) => {
    const taskId = parseInt(req.params.id, 10);
    const task = tasks.find(t => t.id === taskId);

    if (!task) {
        return res.status(404).send('Error: Task not found.');
    }
    const responseText = `ID: ${task.id}\nTitle: ${task.title}\nDescription: ${task.description}\nStatus: ${task.status}`;
    res.status(200).send(responseText);
});

// POST /tasks - Add a new task
app.post('/tasks', (req, res) => {
    const { title, description } = req.body;
    const newTask = {
        id: nextId++,
        title,
        description,
        status: 'pending' // Default status
    };
    tasks.push(newTask);
    res.status(201).send(`Task added successfully with ID: ${newTask.id}`);
});

// PUT /tasks/:id - Update an existing task
app.put('/tasks/:id', (req, res) => {
    const taskId = parseInt(req.params.id, 10);
    const { title, description, status } = req.body;
    const task = tasks.find(t => t.id === taskId);

    if (!task) {
        return res.status(404).send('Error: Task not found.');
    }

    // Update only the provided fields
    if (title !== undefined) task.title = title;
    if (description !== undefined) task.description = description;
    if (status !== undefined) task.status = status;

    res.status(200).send(`Task with ID: ${taskId} updated successfully.`);
});

// DELETE /tasks/:id - Remove a task by its ID
app.delete('/tasks/:id', (req, res) => {
    const taskId = parseInt(req.params.id, 10);
    const taskIndex = tasks.findIndex(t => t.id === taskId);

    if (taskIndex === -1) {
        return res.status(404).send('Error: Task not found.');
    }

    tasks.splice(taskIndex, 1);
    res.status(200).send(`Task with ID: ${taskId} was deleted successfully.`);
});

// Start the server
app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});

Test the API with Postman

Get all tasks (GET)

1. Set the method to GET and the URL to http://localhost:3000/tasks.

2. Click Send. You will see the current list of tasks as plain text.

Get a single task (GET)

1. Set the method to GET and the URL to http://localhost:3000/tasks/2.

2. Click Send. You will see the full details for the "Develop API" task.

Add a new task (POST)

1. Set the method to POST and the URL to http://localhost:3000/tasks.

2. Go to the Body tab, select raw, and choose JSON.

3. Enter the new task's data:

{
	"title": "Deploy Application",
	"description": "Deploy the final application to a cloud server."
}

Click Send. You will get a plain text confirmation. Run the GET /tasks request again to see that the new task was added with a "pending" status.

Update a task's status (PUT)

1. Set the method to PUT and the URL to http://localhost:3000/tasks/2.

2. Go to the Body tab, select raw, and choose JSON.

3. Enter the field to update:

{
	"status": "completed"
}

1. Click Send. You will receive a success message. Run GET /tasks/2 again to see the updated status.

Delete a task (DELETE)

1. Set the method to DELETE and the URL to http://localhost:30-00/tasks/1.

2. Click Send. You will receive a success message confirming the deletion.