public / sequelize

Transactions

Sequelize supports two ways of using transactions, one will automatically commit or rollback the transaction based on a promise chain and the other leaves it up to the user.

The key difference is that the managed transaction uses a callback that expects a promise to be returned to it while the unmanaged transaction returns a promise.

Auto commit/rollback

return sequelize.transaction(t) {
  return User.create({
    firstName: 'Abraham',
    lastName: 'Lincoln'
  }, {transaction: t}).then(function (user) {
    return user.setShooter({
      firstName: 'John',
      lastName: 'Boothe'
    }, {transction: t});
  }).then(function () {
    // Transaction has been committed
  }).catch(function (err) {
    // Transaction has been rolled back
    // err is whatever rejected the promise chain returned to the transaction callback
  });
});

Handled by user

return sequelize.transaction().function (t) {
  return User.create({
    firstName: 'Homer',
    lastName: 'Simpson'
  }, {transaction: t}).then(function (user) {
    return user.addSibling({
      firstName: 'Lisa',
      lastName: 'Simpson'
    }, {transction: t});
  }).then(function () {
    t.commit();
  }).catch(function (err) {
    t.rollback();
  });
});

Using transactions with other sequelize methods

The transaction option goes with most other options, which are usually the first argument of a method. For methods that take values, like .create, .update(), .updateAttributes() and more transaction should be passed to the option in the second argument. If unsure, refer to the api documentation for the method you are using to be sure of the signature.