org.datanucleus.state

Class RelationshipManagerImpl

java.lang.Object

org.datanucleus.state.RelationshipManagerImpl

All Implemented Interfaces:

RelationshipManager

public class RelationshipManagerImpl
extends Object
implements RelationshipManager

Manager for (bidirectional) relationships of a class. Designed as a stand-alone process to run just before flush. Updates on bidirectional relations are registered during the persistence process. Call to checkConsistency() will check for consistency and throw exceptions as appropriate. Call to process() will perform updates at the other side of the registered relations so all is consistent.

Constructor Summary

Constructors

Constructor and Description
RelationshipManagerImpl(ObjectProvider op) Constructor.

Method Summary

Modifier and Type	Method and Description
void	checkConsistency() Method to check for consistency the managed relations of this object with the related objects.
protected void	checkManyToManyBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to check consistency of the passed field as M-N.
protected void	checkManyToOneBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to check the consistency of the passed field as N-1.
protected void	checkOneToManyBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to check the consistency of the passed field as 1-N.
protected void	checkOneToOneBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to check the consistency of the passed field as 1-1.
void	clearFields() Convenience method to clear all fields from being managed.
boolean	managesField(int fieldNumber) Accessor for whether a field is being managed.
void	process() Method to process the (bidirectional) relations for this object.
protected void	processManyToManyBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to process all M-N bidirectional fields.
protected void	processManyToOneBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to process all N-1 bidirectional fields.
protected void	processOneToManyBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to process all 1-N bidirectional fields.
protected void	processOneToOneBidirectionalRelation(AbstractMemberMetaData mmd, ClassLoaderResolver clr, ExecutionContext ec, List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes) Method to process all 1-1 bidir fields.
void	relationAdd(int fieldNumber, Object val) Method to register a change in the contents of a container field, with an object being added.
void	relationChange(int fieldNumber, Object oldValue, Object newValue) Method that is called when the user calls setXXX() on a field.
void	relationRemove(int fieldNumber, Object val) Method to register a change in the contents of a container field, with an object being removed.

Methods inherited from class java.lang.Object

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

Constructor Detail

RelationshipManagerImpl

public RelationshipManagerImpl(ObjectProvider op)

Constructor.

Parameters:

op - ObjectProvider for the object that we are managing relations for.

Method Detail

clearFields

public void clearFields()

Description copied from interface: RelationshipManager

Convenience method to clear all fields from being managed.

Specified by:

clearFields in interface RelationshipManager

relationChange

public void relationChange(int fieldNumber,
                           Object oldValue,
                           Object newValue)

Description copied from interface: RelationshipManager

Method that is called when the user calls setXXX() on a field.

Specified by:

relationChange in interface RelationshipManager

Parameters:

fieldNumber - Number of the field

oldValue - The old value

newValue - The new value

relationAdd

public void relationAdd(int fieldNumber,
                        Object val)

Description copied from interface: RelationshipManager

Method to register a change in the contents of a container field, with an object being added.

Specified by:

relationAdd in interface RelationshipManager

Parameters:

fieldNumber - Number of the field

val - Value being added

relationRemove

public void relationRemove(int fieldNumber,
                           Object val)

Description copied from interface: RelationshipManager

Method to register a change in the contents of a container field, with an object being removed.

Specified by:

relationRemove in interface RelationshipManager

Parameters:

fieldNumber - Number of the field

val - Value being removed

managesField

public boolean managesField(int fieldNumber)

Accessor for whether a field is being managed.

Specified by:

managesField in interface RelationshipManager

Parameters:

fieldNumber - Number of the field

Returns:

Whether it is currently managed

checkConsistency

public void checkConsistency()

Description copied from interface: RelationshipManager

Method to check for consistency the managed relations of this object with the related objects.

Specified by:

checkConsistency in interface RelationshipManager

process

public void process()

Description copied from interface: RelationshipManager

Method to process the (bidirectional) relations for this object.

Specified by:

process in interface RelationshipManager

checkOneToOneBidirectionalRelation

protected void checkOneToOneBidirectionalRelation(AbstractMemberMetaData mmd,
                                                  ClassLoaderResolver clr,
                                                  ExecutionContext ec,
                                                  List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to check the consistency of the passed field as 1-1. Processes the case where we had a 1-1 field set at this side previously to some value and now to some other value. We need to make sure that all of the affected objects are now related consistently. Taking an example

a.b = b1; a.b = b2;

so A's b field is changed from b1 to b2. The following changes are likely to be necessary

• b1.a = null - so we null out the old related objects link back to this object
• b2.oldA = null - if b2 was previously related to a different A, null out that objects link to b2
• b2.a = a - set the link from b2 back to a so it is bidirectional

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the field

checkOneToManyBidirectionalRelation

protected void checkOneToManyBidirectionalRelation(AbstractMemberMetaData mmd,
                                                   ClassLoaderResolver clr,
                                                   ExecutionContext ec,
                                                   List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to check the consistency of the passed field as 1-N.

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the collection

checkManyToOneBidirectionalRelation

protected void checkManyToOneBidirectionalRelation(AbstractMemberMetaData mmd,
                                                   ClassLoaderResolver clr,
                                                   ExecutionContext ec,
                                                   List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to check the consistency of the passed field as N-1. Processes the case where we had an N-1 field set at this side previously to some value and now to some other value.That is, this object was in some collection/map originally, and now should be in some other collection/map. So in terms of an example this object "a" was in collection "b1.as" before and is now in "b2.as". The following changes are likely to be necessary

• b1.getAs().remove(a) - remove it from b1.as if still present
• b2.getAs().add(a) - add it to b1.as if not present

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the field

checkManyToManyBidirectionalRelation

protected void checkManyToManyBidirectionalRelation(AbstractMemberMetaData mmd,
                                                    ClassLoaderResolver clr,
                                                    ExecutionContext ec,
                                                    List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to check consistency of the passed field as M-N.

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the collection

processOneToOneBidirectionalRelation

protected void processOneToOneBidirectionalRelation(AbstractMemberMetaData mmd,
                                                    ClassLoaderResolver clr,
                                                    ExecutionContext ec,
                                                    List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to process all 1-1 bidir fields. Processes the case where we had a 1-1 field set at this side previously to some value and now to some other value. We need to make sure that all of the affected objects are now related consistently. Taking an example

a.b = b1; a.b = b2;

so A's b field is changed from b1 to b2. The following changes are likely to be necessary

• b1.a = null - so we null out the old related objects link back to this object
• b2.oldA = null - if b2 was previously related to a different A, null out that objects link to b2
• b2.a = a - set the link from b2 back to a so it is bidirectional

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the field

processOneToManyBidirectionalRelation

protected void processOneToManyBidirectionalRelation(AbstractMemberMetaData mmd,
                                                     ClassLoaderResolver clr,
                                                     ExecutionContext ec,
                                                     List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to process all 1-N bidirectional fields.

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the collection

processManyToOneBidirectionalRelation

protected void processManyToOneBidirectionalRelation(AbstractMemberMetaData mmd,
                                                     ClassLoaderResolver clr,
                                                     ExecutionContext ec,
                                                     List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to process all N-1 bidirectional fields. Processes the case where we had an N-1 field set at this side previously to some value and now to some other value.That is, this object was in some collection/map originally, and now should be in some other collection/map. So in terms of an example this object "a" was in collection "b1.as" before and is now in "b2.as". The following changes are likely to be necessary

• b1.getAs().remove(a) - remove it from b1.as if still present
• b2.getAs().add(a) - add it to b1.as if not present

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the collection

processManyToManyBidirectionalRelation

protected void processManyToManyBidirectionalRelation(AbstractMemberMetaData mmd,
                                                      ClassLoaderResolver clr,
                                                      ExecutionContext ec,
                                                      List<org.datanucleus.state.RelationshipManagerImpl.RelationChange> changes)

Method to process all M-N bidirectional fields.

Parameters:

mmd - MetaData for the field

clr - ClassLoader resolver

ec - ExecutionContext

changes - List of changes to the collection