I am trying to use Mongoose transactions (specifically the form mongoose.connection.transaction, not startTransaction see Connection#transaction() at this location: https://mongoosejs.com/docs/transactions.html).
I have found that if I try to send an Express response inside the transaction it gives the error:
Attempted illegal state transition from [TRANSACTION_COMMITTED] to [TRANSACTION_ABORTED]
...so for example, this gives the error:
await mongoose.connection.transaction(async (session) => {
//...a bunch of mongoose stuff here - it doesn't really matter what it is.
res.status(200).json({someObject});
}
...but this works fine:
await mongoose.connection.transaction(async (session) => {
//...a bunch of mongoose stuff here - it doesn't really matter what it is.
}
res.status(200).json({someObject});
Why does the second one work but the first one fail? There's no return statement for the res.send - I can put code after it that executes fine.
Also the DB has the desired resulting state in either case.
...but if I have the response inside the transaction it fails, and outside it works.
Now you may say, "Just take your response out of the transaction." Yes, indeed. ...but I want to understand why!
(Mongoose 7.0.1, Express 4.17.3, Node 16.20.0)
