Notes

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
name: { type: String, required: true },
email: { type: String, required: true, unique: true },
// Add other user fields as needed
});

module.exports = mongoose.model('User', userSchema);




const mongoose = require('mongoose');

const productSchema = new mongoose.Schema({
name: { type: String, required: true },
description: { type: String, required: true },
price: { type: Number, required: true },
// Add other product fields as needed
});

module.exports = mongoose.model('Product', productSchema);





const mongoose = require('mongoose');

const orderSchema = new mongoose.Schema({
user: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
products: [
{
product: { type: mongoose.Schema.Types.ObjectId, ref: 'Product', required: true },
quantity: { type: Number, required: true },
},
],
totalAmount: { type: Number, required: true },
// Add other order fields as needed
});

module.exports = mongoose.model('Order', orderSchema);








const mongoose = require('mongoose');

const transactionSchema = new mongoose.Schema({
order: { type: mongoose.Schema.Types.ObjectId, ref: 'Order', required: true },
paymentMethod: { type: String, required: true },
transactionAmount: { type: Number, required: true },
// Add other transaction fields as needed
});

module.exports = mongoose.model('Transaction', transactionSchema);






Now, let's create the routes and controllers:
src/routes/orders.js
const express = require('express');
const router = express.Router();
const Order = require('../models/order');
const Transaction = require('../models/transaction');

// 1. Place Order
router.post('/', async (req, res) => {
try {
const { user, products, totalAmount } = req.body;
const order = new Order({ user, products, totalAmount });
const savedOrder = await order.save();

res.status(201).json(savedOrder);
} catch (err) {
res.status(400).json({ error: err.message });
}
});

// 2. Get Order Details
router.get('/:id', async (req, res) => {
try {
const order = await Order.findById(req.params.id)
.populate('user', 'name email')
.populate('products.product', 'name description price');

if (!order) {
return res.status(404).json({ error: 'Order not found' });
}

res.json(order);
} catch (err) {
res.status(500).json({ error: err.message });
}
});

// 3. Get Transaction Details
router.get('/:id/transaction', async (req, res) => {
try {
const transaction = await Transaction.findOne({ order: req.params.id })
.populate('order', 'totalAmount')
.populate({
path: 'order',
populate: {
path: 'products.product',
model: 'Product',
select: 'name description price',
},
});

if (!transaction) {
return res.status(404).json({ error: 'Transaction not found' });
}

res.json(transaction);
} catch (err) {
res.status(500).json({ error: err.message });
}
});

module.exports = router;






src/app.js
const express = require('express');
const mongoose = require('mongoose');
const ordersRouter = require('./routes/orders');

const app = express();
app.use(express.json());

// Connect to MongoDB
mongoose.connect('mongodb://localhost/e-commerce', {
useNewUrlParser: true,
useUnifiedTopology: true,
})
.then(() => console.log('MongoDB connected'))
.catch((err) => console.error('MongoDB connection error:', err));

// Routes
app.use('/api/orders', ordersRouter);

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

Here's how the APIs work:

Place Order

Send a POST request to /api/orders with the user, products, and totalAmount in the request body.
A new order document will be created in the orders collection, with references to the user and products.


Get Order Details

Send a GET request to /api/orders/:id, replacing :id with the ID of the order.
The response will include the order details, with the user and product details populated using MongoDB's population feature.


Get Transaction Details

Send a GET request to /api/orders/:id/transaction, replacing :id with the ID of the order.
The response will include the transaction details, with the order details and product details populated using MongoDB's population feature.



Note that in this example, we assume that the transaction is created separately after placing the order. You may need to modify the code to suit your application's logic.
Also, remember to handle authentication, authorization, and input validation in a production environment.