com.goldencode.p2j.persist

Class InverseSyncher

java.lang.Object

com.goldencode.p2j.persist.AssociationSyncher

com.goldencode.p2j.persist.InverseSyncher

final class InverseSyncher
extends AssociationSyncher

Automatically synchronizes both ends of a foreign key association, based upon changes made to the values of DMO properties which participate in a legacy foreign key. This class drives synchronization when it is triggered by changes to the DMO at the referent, or "inverse", or foreign end of the association. In P2J, the association is actually bidirectional; however, in the database schema, the end of the association which stores the foreign key determines which end is the referencing end and which is the referent end.

See Also:

AssociationSyncher, ForeignResolver, RelationInfo, RecordBuffer

Nested Class Summary

Nested classes/interfaces inherited from class com.goldencode.p2j.persist.AssociationSyncher

AssociationSyncher.Helper, AssociationSyncher.OneToManyHelper, AssociationSyncher.OneToOneHelper

Field Summary

Fields

Modifier and Type	Field and Description
private ForeignResolver	resolver Object which resolves a list of DMO IDs from legacy keys

Fields inherited from class com.goldencode.p2j.persist.AssociationSyncher

buffer, foreignSetter, helper, lockTable

Constructor Summary

Constructors

Constructor and Description
InverseSyncher(RecordBuffer buffer, RelationInfo info) Constructor.

Method Summary

Modifier and Type	Method and Description
protected java.util.Set<java.lang.String>	getLegacyKeys() Retrieve the set of property names which represent the columns which comprise the legacy key joining two records.
protected void	preSynch(java.util.Set<Record> newLocalDMOs, Record newForeignDMO) The foreign end of an association has changed.
protected Record	retrieveForeignDMO() Retrieve the DMO at the foreign end of the association, which coincides with the DMO whose property changes triggered synchronization.
protected java.util.Set<Record>	retrieveLocalDMOs() Retrieve the set of DMOs which comprise the local end of the foreign association.

Methods inherited from class com.goldencode.p2j.persist.AssociationSyncher

acquireLock, attemptSynch

Methods inherited from class java.lang.Object

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

Field Detail

resolver

private final ForeignResolver resolver

Object which resolves a list of DMO IDs from legacy keys

Constructor Detail

InverseSyncher

InverseSyncher(RecordBuffer buffer,
               RelationInfo info)

Constructor.

Parameters:

buffer - Record buffer containing the DMO whose property change(s) will trigger synchronization attempts.

info - Foreign relation descriptor object.

Method Detail

getLegacyKeys

protected java.util.Set<java.lang.String> getLegacyKeys()

Retrieve the set of property names which represent the columns which comprise the legacy key joining two records. Changes to these properties trigger synchronization of the two ends of a foreign key association. A set is returned because legacy keys are often composites of multiple columns.

Specified by:

getLegacyKeys in class AssociationSyncher

Returns:

Set of property names comprising the legacy key. Although they should generally be the same as those of the referencing end of the association, this implementation returns the property names associated with the referent end.

preSynch

protected void preSynch(java.util.Set<Record> newLocalDMOs,
                        Record newForeignDMO)
                 throws java.lang.IllegalAccessException,
                        java.lang.reflect.InvocationTargetException

The foreign end of an association has changed. Find the old local DMOs it referenced. If different than the new local DMOs provided, null out the foreign DMO reference from each of the old local DMOs.

Specified by:

preSynch in class AssociationSyncher

Parameters:

newLocalDMOs - Set of zero or more local DMOs which are about to be updated with the new association.

newForeignDMO - Foreign DMO which is about to be updated with the new association.

Throws:

java.lang.IllegalAccessException - if an access error occurs while invoking a method using reflection.

java.lang.reflect.InvocationTargetException - if a method invoked using reflection throws an exception.

retrieveLocalDMOs

protected java.util.Set<Record> retrieveLocalDMOs()
                                           throws PersistenceException

Retrieve the set of DMOs which comprise the local end of the foreign association. The records are resolved using the new property values of the underlying buffer's current record. This method uses AssociationSyncher.acquireLock(java.lang.Long, com.goldencode.p2j.persist.lock.LockType) to lock the records before they are retrieved.

If the association is one-to-one, the set will contain zero or one records.

If the association is one-to-many, the set may contain zero or more records.

Specified by:

retrieveLocalDMOs in class AssociationSyncher

Returns:

Set of newly resolved local DMOs. The set may be empty, but it will not be null.

Throws:

PersistenceException - if there are any errors retrieving DMOs from the database.

retrieveForeignDMO

protected Record retrieveForeignDMO()
                             throws PersistenceException

Retrieve the DMO at the foreign end of the association, which coincides with the DMO whose property changes triggered synchronization. Because these changes would not have been possible without an exclusive record lock, this method assumes one has been acquired and does not attempt to acquire a lock.

Specified by:

retrieveForeignDMO in class AssociationSyncher

Returns:

Foreign DMO.

Throws:

PersistenceException - if there are any errors retrieving the DMO from the database.