Bad request returned from google cloud function

I’m trying to get a google cloud function to work to open a stripe checkout, currently it isn’t working however.

This is the function:

const functions = require('firebase-functions');
const express = require('express');
const app = express();
const cors = require('cors')({origin: true});
app.use(cors);
app.use(express.json())
app.use(express.static('public'))

app.use(
  express.urlencoded({
    extended: false,
  })
)


const stripe = require('stripe')(functions.config().stripe.secret_key);


exports.createStripeCheckout2 = functions.region('europe-west2').https.onCall(async(req, res) => {

  const cust = req.body.customerId
  const price = req.body.priceId
  const quantity = req.body.students
  const quantityA = Number(quantity)

  const session = await stripe.checkout.sessions.create({
    payment_method_types: ["card"],
    mode: 'subscription',
    allow_promotion_codes: true,
    customer: 'cus_MQrpENhbL84RFD',  
    line_items: [
      {
        price: 'price_1LaJC1CKMdmWgnyspBbFet9v',
        // For metered billing, do not pass quantity
        quantity: 1,
      },
    ],
    success_url: `https://learning-platform-835f9.web.app/`,
    cancel_url: `https://learning-platform-835f9.web.app/`,
  });
  res.redirect(session.url);
});

Returns the following:

{"error":{"message":"Bad Request","status":"INVALID_ARGUMENT"}}

With this in the console: Failed to load resource: the server responded with a status of 400 ()

>Solution :

The onCall() is different than onRequest() and the parameters in the function are not Request and Response from Express. It seems you are trying to call this function like a REST API using fetch or equivalent. If so, you must sent the request with the details mentioned in the documentation like the Content-Type header must be present and the body must have a data property.

In this case, using onRequest function should work keeping rest of the code as it is.