(Experimental) MongoDB Sessions & Transactions

MongoDB supports transactions using sessions (requires a replica set).

Starting a Session

const session = mongo.startSession();

Using a Session in Operations

Pass the session as the second argument to mongo.from():

const session = mongo.startSession();
try {
  await mongo
    .from(User, { session })
    .insert({ name: "John", email: "john@test.com" });
  await mongo
    .from(User, { session })
    .insert({ name: "Jane", email: "jane@test.com" });
  await session.commitTransaction();
} catch (error) {
  await session.abortTransaction();
  throw error;
}

Multi-Collection Transactions

const session = mongo.startSession();
try {
  const user = await mongo
    .from(User, { session })
    .insert({ name: "John", email: "john@test.com" });
  await mongo
    .from(Order, { session })
    .insert({ userId: user.id, total: 99.99 });
  await session.commitTransaction();
} catch (error) {
  await session.abortTransaction();
  throw error;
}

Best Practices

• Always commit or abort the session.
• Use sessions for multi-document atomicity.
• Sessions require a replica set.

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