Accessing Firestore via Cloud Function - node.js

Question

So i have 2 Cloud Functions within the same file:
exports.Auth = functions.region('europe-west1').https.onRequest((req, res) =>
and
exports.IPN = functions.region('europe-west1').https.onRequest((req, res) =>
When adding the following code right at the start of my Auth function it adds a new document to the Firestore as expected, however, when i add the same code at the start of my IPN function, which is currently being called via Paypal's IPN Simulator, it does nothing, no errors.
let pin = RandomPIN(10, '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');
var userRef = db.collection('Users').doc(pin);
var setWithOptions = userRef.set({ Activated: false }, { merge: true });
console.log("PIN: "+pin);
What on earth is going on, i must be missing something?
Thanks in advance.
Update:
Here are the logs, first with the 2 middle lines commented and then uncommented It seems to be silently failing, i'm just not sure what is causing it.
Update with Complete function:
exports.IPN = functions.region('europe-west1').https.onRequest((req, res) =>
{
console.log("IPN Notification Event Received");
let pin = RandomPIN(10, '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');
var userRef = db.collection('Users').doc(pin);
var setWithOptions = userRef.set({ Activated: false }, { merge: true });
console.log("PIN: "+pin);
if (req.method !== "POST")
{
console.error("Request method not allowed.");
res.status(405).send("Method Not Allowed");
}
else
{
console.log("IPN Notification Event received successfully.");
res.status(200).end();
}
let ipnTransactionMessage = req.body;
// Convert JSON ipn data to a query string since Google Cloud Function does not expose raw request data.
let formUrlEncodedBody = querystring.stringify(ipnTransactionMessage);
// Build the body of the verification post message by prefixing 'cmd=_notify-validate'.
let verificationBody = `cmd=_notify-validate&${formUrlEncodedBody}`;
console.log(`Verifying IPN: ${verificationBody}`);
let options = {
method: "POST",
uri: getPaypalURI(),
body: verificationBody,
};
// POST verification IPN data to paypal to validate.
request(options, function callback(error, response, body)
{
if(!error && response.statusCode === 200)
{
if(body === "VERIFIED")
{
console.log(`Verified IPN: IPN message for Transaction ID: ${ipnTransactionMessage.txn_id} is verified.`);
SendPIN(ipnTransactionMessage.payer_email, pin);
}
else if(body === "INVALID")
console.error(`Invalid IPN: IPN message for Transaction ID: ${ipnTransactionMessage.txn_id} is invalid.`);
else
console.error("Unexpected reponse body.");
}
else
{
console.error(error);
console.log(body);
}
});
});

Answer 1

Indeed it is a problem of Promises chaining and also a problem due to the request library: request supports callback interfaces natively but does not return a promise, which is what you must do within a Cloud Function.
I would suggest that you watch these official Firebase videos from Doug : https://www.youtube.com/watch?v=7IkUgCLr5oA&t=28s and https://www.youtube.com/watch?v=652XeeKNHSk which explain this key concept.
You can use request-promise (https://github.com/request/request-promise) and the rp() method which "returns a regular Promises/A+ compliant promise".
It is not clear what SendPIN() is doing. Let's make the assumption it returns a Promise. If this is true, you could adapt your code along the following lines:
//....
const rp = require('request-promise');
//....
exports.IPN = functions.region('europe-west1').https.onRequest((req, res) => {
console.log('IPN Notification Event Received');
let pin = RandomPIN(
10,
'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
);
var userRef = db.collection('Users').doc(pin);
if (req.method !== 'POST') {
console.error('Request method not allowed.');
res.status(405).send('Method Not Allowed');
} else {
let ipnTransactionMessage;
userRef
.set({ Activated: false }, { merge: true })
.then(() => {
console.log('PIN: ' + pin);
ipnTransactionMessage = req.body;
// Convert JSON ipn data to a query string since Google Cloud Function does not expose raw request data.
let formUrlEncodedBody = querystring.stringify(ipnTransactionMessage);
// Build the body of the verification post message by prefixing 'cmd=_notify-validate'.
let verificationBody = `cmd=_notify-validate&${formUrlEncodedBody}`;
console.log(`Verifying IPN: ${verificationBody}`);
let options = {
method: 'POST',
uri: getPaypalURI(),
body: verificationBody
};
// POST verification IPN data to paypal to validate.
return rp(options);
})
.then(response => {
//Not sure what you will get within the response object...
console.log(
`Verified IPN: IPN message for Transaction ID: ${
ipnTransactionMessage.txn_id
} is verified.`
);
return SendPIN(ipnTransactionMessage.payer_email, pin); //It is not clear what SendPIN is doing, let's make the assumption it returns a Promise...
})
.then(() => {
res.send('Success');
return null;
})
.catch(err => {
console.error(
`Invalid IPN: IPN message for Transaction ID: ${
ipnTransactionMessage.txn_id
} is invalid.`
);
res
.status(500)
.send(
'Error: ' +
err +
` - Invalid IPN: IPN message for Transaction ID: ${
ipnTransactionMessage.txn_id
} is invalid.`
);
return null;
});
}
});