org.eclipse.persistence.descriptors
Class SelectedFieldsLockingPolicy

java.lang.Object
  org.eclipse.persistence.descriptors.FieldsLockingPolicy
      org.eclipse.persistence.descriptors.SelectedFieldsLockingPolicy

All Implemented Interfaces:

Serializable, Cloneable, org.eclipse.persistence.internal.descriptors.OptimisticLockingPolicy

public class SelectedFieldsLockingPolicy
extends FieldsLockingPolicy

Purpose: An implementation of the OptimisticLockingPolicy interface. This policy compares selected fields in the WHERE clause when doing an update or a delete. If any field has been changed, an optimistic locking exception will be thrown. Note that the fields specified must be mapped and not be primary keys.

NOTE: This policy can only be used inside a unit of work.

Since:

TopLink 2.5

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.eclipse.persistence.internal.descriptors.OptimisticLockingPolicy

org.eclipse.persistence.internal.descriptors.OptimisticLockingPolicy.LockOnChange

Constructor Summary

SelectedFieldsLockingPolicy()
PUBLIC: Create a new selected fields locking policy.

Method Summary

void	addLockFieldName(String fieldName) PUBLIC: Add a fieldname to lock on.
void	addLockValuesToTranslationRow(ObjectLevelModifyQuery query) INTERNAL: Values to be included in the locking mechanism are added to the translation row.
Vector	getLockFields() INTERNAL: Returns the lock fields
void	initialize(org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: It is responsible for initializing the policy;
void	setLockFieldNames(Vector lockFieldNames) PUBLIC: Set the field names to lock on.
void	setLockFields(Map lockFieldsByTable) INTERNAL: Used to set the field names to be used in this policy.

Methods inherited from class org.eclipse.persistence.descriptors.FieldsLockingPolicy

addLockFieldsToUpdateRow, buildDeleteExpression, buildUpdateExpression, clone, compareWriteLockValues, getBaseValue, getLockOnChangeMode, getValueToPutInCache, getVersionDifference, getWriteLockField, getWriteLockUpdateExpression, getWriteLockValue, initializeProperties, isCascaded, isNewerVersion, isNewerVersion, isStoredInCache, mergeIntoParentCache, setDescriptor, setLockOnChangeMode, setupWriteFieldsForInsert, shouldUpdateVersionOnMappingChange, shouldUpdateVersionOnOwnedMappingChange, supportsWriteLockValuesComparison, updateRowAndObjectForUpdate, validateDelete, validateUpdate

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SelectedFieldsLockingPolicy

public SelectedFieldsLockingPolicy()

PUBLIC: Create a new selected fields locking policy. A field locking policy is based on locking on the specified fields by comparing with their previous values to detect field-level collisions. Note: the unit of work must be used for all updates when using field locking.

Method Detail

addLockFieldName

public void addLockFieldName(String fieldName)

PUBLIC: Add a fieldname to lock on. All fields in this list will be compared when Updating if the value of any of the fields does not match the value in memory, an OptimisticLockException will be thrown. Note: An Automatic update will not be done on this field, only a comparison occurs.

addLockValuesToTranslationRow

public void addLockValuesToTranslationRow(ObjectLevelModifyQuery query)
                                   throws DatabaseException

INTERNAL: Values to be included in the locking mechanism are added to the translation row. For changed fields the normal build row is ok as only changed fields matter.

Specified by:

addLockValuesToTranslationRow in interface org.eclipse.persistence.internal.descriptors.OptimisticLockingPolicy

Specified by:

addLockValuesToTranslationRow in class FieldsLockingPolicy

Throws:

DatabaseException

getLockFields

public Vector getLockFields()

INTERNAL: Returns the lock fields

initialize

public void initialize(org.eclipse.persistence.internal.sessions.AbstractSession session)

INTERNAL: It is responsible for initializing the policy;

Specified by:

initialize in interface org.eclipse.persistence.internal.descriptors.OptimisticLockingPolicy

Overrides:

initialize in class FieldsLockingPolicy

setLockFieldNames

public void setLockFieldNames(Vector lockFieldNames)

PUBLIC: Set the field names to lock on. All fields in this list will be compared when Updating. If the value of any of the fields does not match the value in memory, an OptimisticLockException will be thrown. Note: An Automatic update will not be done on this field, only a comparison occurs.

setLockFields

public void setLockFields(Map lockFieldsByTable)

INTERNAL: Used to set the field names to be used in this policy.