Connection#transaction: Should reset $isNew during the retry

[wongsean]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

7.4.1

Node.js version

16.18.1

MongoDB server version

4.2

Typescript version (if applicable)

4.7.3

Description

I'm encountering a similar issue as described in #8852, while using the mongoose built-in transaction wrapper Connection#transaction.

To simplify the problem, I've created the reproducible code below.

The problem arises when I attempt to save a new document within a transaction. If a TransientTransactionError occurs during the first try and triggers a retry, the doc's $isNew flag is not reset before the second attempt. Consequently, the subsequent save operation throws a DocumentNotFound error because it attempts to send an update operation behind the scenes instead of an insert.

Upon digging into the code, I discovered that the state reset, which should occur here, only takes place after two failed tries (in the case of a retry), and not before each retry attempt.

Steps to Reproduce

const doc = new Model({ a: "b" });

await connection.transaction(
  async (session) => {
    await doc.save({ session });
    throw new MongoServerError({
      errorLabels: ["TransientTransactionError"],
    });
  },
  { readPreference: "primary" }
);

Expected Behavior

I expected that the state should be reset before every retry attempt, which should prevent the DocumentNotFound error from occurring.

At the moment, my workaround is moving const doc = new Model({ a: "b" }); into the transaction block.