Combine file API with transactions for file saving or deleting - node.js

Question

I am using node 8.11.1 with pg-promise 8.4.4 to handle queries and transactions in PostgreSQL. This is about node, but I guess is the same logic in other servers/tools too.
The scenario is common. I want to save an image file in a folder, then if this is successful, insert its details in the database, get the returned id and then do another insert in a secondary, many-to-many table.
Clearly, I need a transaction for the insert queries. But what about the actual file saving? My approach is
fs.rename(oldpath, newpath, (err) => {
if (err){throw new Error ;}
db.tx('my-transaction', t => {
return t.one('INSERT INTO images(whatever) VALUES($1) RETURNING id', ['whatever'])
.then(user => {
return t.batch([
t.none('INSERT INTO mtm(userId, name) VALUES($1, $2)', [user.id, 'created'])
]);
});
})
.then(data => {
// success
})
.catch(error => {
// error
});
}); //fs rename
Ok, if there is no error while saving the image file with fs.rename, then proceed with the transaction.
If there is an error while saving the image, nothing will execute, so all good.
But the problem is, what if the image is saved and there is an error in the transaction? I will end up with an image saved and nothing in the database. Sure, user will get an error and will have to re-upload, but I still have images in my server that are not related to anything. I would like to avoid this.
The solution would be to incorporate the image saving in the transaction, so if anything fails, nothing is completed. How can I do this? I dont know if the file API can be inside a query-related transaction. I dont even know if I am in the right mindset here.
Please advice or help me code this.
Thank you

Answer 1

Simply remove the file, if transaction fails (or you can rename it back, if you prefer):
const fs = require('fs-extra');
async function saveAll(oldpath, newpath) {
await fs.rename(oldpath, newpath);
try {
return await db.tx('my-transaction', async t => {
const imageId = await t.one('INSERT INTO images(whatever) VALUES($1) RETURNING id', ['whatever'], a => a.id);
await t.none('INSERT INTO mtm(userId, name) VALUES($1, $2)', [imageId, 'created']);
return imageId;
});
} catch (e) {
await fs.unlink(newpath); // deleting the file
throw e;
}
}
Function saveAll will return the new imageId, if successful, or throw an error, if anything fails:
async test() {
try {
const imageId = await saveAll('old-path', 'new-path');
// we are all good
} catch(e) {
// something failed, as per the error details
}
}