You were almost there, but you forgot to include an await in the main function and also inside the sendMail function for the mailTransport.sendMail call.
This should work correctly:
exports.sendEmails = functions.database.ref("/devices/{device_ID}/history/{alert_ID}")
.onWrite(
async (snapshot, context) => {
await sendMail(snapshot, context);
return true;
}
);
async function sendMail(snapshot, context){
const { before, after } = snapshot;
// new alert created
if (before.val() == null) {
console.log('DEBUG:: NEW ALERT');
// get owners uID from device ID
const deviceRef = db.collection('deviceToUid').doc(context.params.device_ID);
const uidDoc = await deviceRef.get();
if(!uidDoc.exists){
functions.logger.info("No such document!");
return;
}
// get users email from uID
const userRef = db.collection('users').doc(uidDoc.data()[context.params.device_ID]).collection('user-info');
// get users contact
const contactRef = db.collection('users').doc(uidDoc.data()[context.params.device_ID]).collection('contacts');
const [userInfo, contactList] = await Promise.all([userRef.get(), contactRef.get()]);
if(userInfo.empty){
functions.logger.info("No such collection!");
return;
}
const email = userInfo.docs[0].id; // owners email
let contacts = []; // initialize contact list
contactList.forEach(
(doc) => {
if(doc.data().confirmed){
contacts.push(doc.id);
}
}
)
const mailTransport = nodemailer.createTransport({
service: 'gmail',
auth: {
user: SENDER_EMAIL,
pass: SENDER_PASSWORD,
},
});
const mailOptions = {
from: 'ALERT <<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="0f61607d6a7f63764f69667d6a6d6e7c6a216c6062">[email protected]</a>>',
to: email,
bcc: contacts,
subject: `...Motion detected`,
html: `<p dir=ltr>New Alert...</p>`
};
await mailTransport.sendMail(mailOptions, function (error, info) {
if (error) {
console.log(error);
} else {
console.log('Email sent: ' + info.response);
}
});
return true;
}
}
It's important to use await in the main function to ensure that asynchronous calls are completed before the Cloud Functions container shuts down. More information about this can be found in the documentation on sync, async and promises - and how Cloud Functions are terminated.