Class Transaction

Class Transaction

The transaction object is used to identify a running transaction. It is created by calling Sequelize.transaction().

To run a query under a transaction, you should pass the transaction in the options object.

Params:

Name	Type	Description
sequelize	Sequelize	A configured sequelize Instance
options	Object	An object with options
options.autocommit=true	Boolean	Sets the autocommit property of the transaction.
options.type=true	String	Sets the type of the transaction.
options.isolationLevel=true	String	Sets the isolation level of the transaction.
options.deferrable	String	Sets the constraints to be deferred or immediately checked.
options.readOnly=false	String	Sets the read-only property of the transaction. Such transactions will use read replicas when available

TYPES

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Types can be set per-transaction by passing options.type to sequelize.transaction.Default to DEFERRED but you can override the default type by passing options.transactionType in new Sequelize.Sqlite only.

The possible types to use when starting a transaction:

{
  DEFERRED: "DEFERRED",
  IMMEDIATE: "IMMEDIATE",
  EXCLUSIVE: "EXCLUSIVE"
}

Pass in the desired level as the first argument:

return sequelize.transaction({
  type: Sequelize.Transaction.EXCLUSIVE
}, function (t) {
 // your transactions
}).then(function(result) {
  // transaction has been committed. Do something after the commit if required.
}).catch(function(err) {
  // do something with the err.
});

ISOLATION_LEVELS

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Isolations levels can be set per-transaction by passing options.isolationLevel to sequelize.transaction.Default to REPEATABLE_READ but you can override the default isolation level by passing options.isolationLevel in new Sequelize.

The possible isolations levels to use when starting a transaction:

{
  READ_UNCOMMITTED: "READ UNCOMMITTED",
  READ_COMMITTED: "READ COMMITTED",
  REPEATABLE_READ: "REPEATABLE READ",
  SERIALIZABLE: "SERIALIZABLE"
}

Pass in the desired level as the first argument:

return sequelize.transaction({
  isolationLevel: Sequelize.Transaction.SERIALIZABLE
}, function (t) {
 // your transactions
}).then(function(result) {
  // transaction has been committed. Do something after the commit if required.
}).catch(function(err) {
  // do something with the err.
});

LOCK

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Possible options for row locking. Used in conjunction with find calls:

t1 // is a transaction
t1.LOCK.UPDATE,
t1.LOCK.SHARE,
t1.LOCK.KEY_SHARE, // Postgres 9.3+ only
t1.LOCK.NO_KEY_UPDATE // Postgres 9.3+ only

Usage:

t1 // is a transaction
Model.findAll({
  where: ...,
  transaction: t1,
  lock: t1.LOCK...
});

Postgres also supports specific locks while eager loading by using OF:

UserModel.findAll({
  where: ...,
  include: [TaskModel, ...],
  transaction: t1,
  lock: {
    level: t1.LOCK...,
    of: UserModel
  }
});

UserModel will be locked but TaskModel won't!

commit() -> Promise

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Commit the transaction

rollback() -> Promise

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Rollback (abort) the transaction

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