paypal-rest-sdk "MALFORMED_REQUEST_JSON" on execution - node.js

Question

I'm trying to implement PayPal payments on my website, I can create a payment once the user requests and I send him the redirect approval URL, after clients pay I call the execution on my backend with the payment ID and buyer ID, but I receive the error below
{"response":{"name":"VALIDATION_ERROR","message":"Invalid request - see details","debug_id":"4f3a6da7e0c7d","details":[{"location":"body","issue":"MALFORMED_REQUEST_JSON"}],"links":[],"httpStatusCode":400},"httpStatusCode":400}
I have been trying everything for a few hours, I tried to copy the create payment JSON from anywhere including PayPal API example and still, nothing works.
Also, I wanna redirect the client to success page just after transaction is approved (execute), it has to be handled by the front?
Code
const paypal = require('paypal-rest-sdk');
const dbService = require('../../services/mongodb-service');
const { ObjectId } = require('mongodb');
const getProducts = async () => {
const products = await dbService.getCollection('products');
return await products.find({}).toArray();
}
paypal.configure({
'mode': 'sandbox',
'client_id': 'id',
'client_secret': 'secret'
});
const createPayment = async (productId) => {
const products = await dbService.getCollection('products');
const product = await products.findOne({ '_id': ObjectId(productId) })
if (!product) return Promise.reject('Product not found');
const payment = {
"intent": "sale",
"payer": {
"payment_method": "paypal"
},
"transactions": [{
"amount": {
"currency": "USD",
"total": product.price,
},
"description": product.description,
"payment_options": {
"allowed_payment_method": "IMMEDIATE_PAY"
},
"item_list": {
"items": [{
"name": product.name,
"description": product.description,
"quantity": 1,
"price": product.price,
"tax": 0,
"sku": product._id,
"currency": "USD"
}]
}
}],
"redirect_urls": {
"return_url": "http://localhost:3000/purchase-success",
"cancel_url": "http://localhost:3000/purchase-error"
}
}
const transaction = await _createPay(payment);
const redirect = transaction.links.find(link => link.method === 'REDIRECT');
return redirect;
}
const _createPay = (payment) => {
return new Promise((resolve, reject) => {
paypal.payment.create(payment, (err, payment) => err ? reject(err) : resolve(payment));
});
}
const executePayment = async (paymentId, payerId) => {
try {
const execute = await _executePay(paymentId, payerId);
console.log(execute);
return execute;
} catch (err) { console.log(JSON.stringify(err)) }
}
const _executePay = (paymentId, payerId) => {
return new Promise((resolve, reject) => {
console.log(paymentId, payerId);
paypal.payment.execute(paymentId, payerId, (error, payment) => {
return error ? reject(error) : resolve(JSON.stringify(payment));
})
})
}
module.exports = {
createPayment,
executePayment,
getProducts
}

Answer 1

should be
const _executePay = (paymentId, payerId) => {
return new Promise((resolve, reject) => {
console.log(paymentId, payerId);
var payerIdObj = { payer_id: payerId };
paypal.payment.execute(paymentId, payerIdObj, (error, payment) => {
return error ? reject(error) : resolve(JSON.stringify(payment));
})
})
}
the doc

Answer 2

I was able to resolve it by doing a post request, code:
const _executePay = async (paymentId, payerId) => {
const response = await axios.post(`https://api.sandbox.paypal.com/v1/payments/payment/${paymentId}/execute`, { 'payer_id': payerId }, {
auth: {
username: CLIENT_ID,
password: CLIENT_SECRET
}
})
return response;
}