NPersistence Reference Guide
Lock an entity instance that is contained in the persistence context with the specified lock mode type and with specified properties. If a pessimistic lock mode type is specified and the entity contains a version attribute, the persistence provider must also perform optimistic version checks when obtaining the database lock. If these checks fail, the OptimisticLockException will be thrown. If the lock mode type is pessimistic and the entity instance is found but cannot be locked:
  • the PessimisticLockException will be thrown if the database locking failure causes transaction-level rollback
  • the LockTimeoutException will be thrown if the database locking failure causes only statement-level rollback
If a vendor-specific property or hint is not recognized, it is silently ignored. Portable applications should not rely on the standard timeout hint. Depending on the database in use and the locking mechanisms used by the provider, the hint may or may not be observed.

Namespace: NPersistence
Assembly: NPersistence (in NPersistence.dll) Version: (


void Lock(
	Object entity,
	LockModeType lockMode,
	Dictionary<string, Object> properties


entity instance
lock mode
Dictionary<(Of <(<'String, Object>)>)>
standard and vendor-specific properties and hints


System..::..ArgumentException if the instance is not an entity or is a detached entity
NPersistence..::..TransactionRequiredException if there is no transaction
NPersistence..::..EntityNotFoundException if the entity does not exist in the database when pessimistic locking is performed
NPersistence..::..OptimisticLockException if the optimistic version check fails
NPersistence..::..PessimisticLockException if pessimistic locking fails and the transaction is rolled back
NPersistence..::..LockTimeoutException if pessimistic locking fails and only the statement is rolled back
NPersistence..::..PersistenceException if an unsupported lock call is made

See Also