org.jpox.metadata
Class ForeignKeyMetaData

java.lang.Object
  org.jpox.metadata.MetaData
      org.jpox.metadata.AbstractConstraintMetaData
          org.jpox.metadata.ForeignKeyMetaData

All Implemented Interfaces:

java.io.Serializable, ColumnMetaDataContainer

public class ForeignKeyMetaData
extends AbstractConstraintMetaData
implements ColumnMetaDataContainer

Foreign keys in metadata serve two quite different purposes. First, when generating schema, the foreign key element identifies foreign keys to be generated. Second, when using the database, foreign key elements identify foreign keys that are assumed to exist in the database. This is important for the runtime to properly order insert, update, and delete statements to avoid constraint violations. A foreign-key element can be contained by a field, element, key, value, or join element, if all of the columns mapped are to be part of the same foreign key. A foreign-key element can be contained within a class element. In this case, the column elements are mapped elsewhere, and the column elements contained in the foreign-key element have only the column name.

Since:

1.1

Version:

$Revision: 1.21 $

See Also:

Serialized Form

Field Summary

protected boolean	deferred The deferred attribute specifies whether the foreign key constraint is defined to be checked only at commit time.
protected ForeignKeyAction	deleteAction Foreign keys represent a consistency constraint in the database that must be maintained.
protected boolean	unique The unique attribute specifies whether the foreign key constraint is defined to be a unique constraint as well.
protected ForeignKeyAction	updateAction Foreign keys represent a consistency constraint in the database that must be maintained.

Fields inherited from class org.jpox.metadata.AbstractConstraintMetaData

columnMetaData, columns, memberMetaData, members, name, table

Fields inherited from class org.jpox.metadata.MetaData

extensions, JPOX_VENDOR_NAME, LOCALISER, METADATA_CREATED_STATE, METADATA_INITIALISED_STATE, METADATA_POPULATED_STATE, METADATA_USED_STATE, metaDataState, parent

Constructor Summary

ForeignKeyMetaData(ForeignKeyMetaData fkmd)
Constructor to create a copy of the passed metadata using the provided parent.

ForeignKeyMetaData(java.lang.String name, java.lang.String table, java.lang.String unique, java.lang.String deferred, java.lang.String delete_action, java.lang.String update_action)
Constructor.

Method Summary

ForeignKeyAction	getDeleteAction() Accessor for the delete action
ForeignKeyAction	getUpdateAction() Accessor for the update action
void	initialise() Method to initialise the object, setting up all internal arrays.
boolean	isDeferred() Accessor for whether the FK is deferred
boolean	isUnique() Accessor for the unique flag
java.lang.String	toString(java.lang.String prefix, java.lang.String indent) Returns a string representation of the object using a prefix This can be used as part of a facility to output a MetaData file.

Methods inherited from class org.jpox.metadata.AbstractConstraintMetaData

addColumn, addMember, getColumnMetaData, getMemberMetaData, getName, getNumberOfColumns, getNumberOfMembers, getTable, setName

Methods inherited from class org.jpox.metadata.MetaData

addExtension, addExtension, getExtensions, getNoOfExtensions, getParent, getValueForExtension, getValuesForExtension, hasExtension, isInitialised, isPopulated, isUsed, populate, removeExtension, setInitialised, setParent, setPopulated, setUsed, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jpox.metadata.ColumnMetaDataContainer

addColumn, getColumnMetaData

Field Detail

unique

protected boolean unique

The unique attribute specifies whether the foreign key constraint is defined to be a unique constraint as well. This is most often used with one-to-one mappings.

deferred

protected boolean deferred

The deferred attribute specifies whether the foreign key constraint is defined to be checked only at commit time.

deleteAction

protected ForeignKeyAction deleteAction

Foreign keys represent a consistency constraint in the database that must be maintained. The user can specify by the value of the delete-action attribute what happens if the target row of a foreign key is deleted.

updateAction

protected ForeignKeyAction updateAction

Foreign keys represent a consistency constraint in the database that must be maintained. The user can specify by the update-action attribute what happens if the target row of a foreign key is updated.

Constructor Detail

ForeignKeyMetaData

public ForeignKeyMetaData(ForeignKeyMetaData fkmd)

Constructor to create a copy of the passed metadata using the provided parent.

Parameters:

fkmd - The metadata to copy

ForeignKeyMetaData

public ForeignKeyMetaData(java.lang.String name,
                          java.lang.String table,
                          java.lang.String unique,
                          java.lang.String deferred,
                          java.lang.String delete_action,
                          java.lang.String update_action)

Constructor.

Parameters:

name - Name of the foreign key

table - Table to apply the FK to

unique - Whether the key is unique

deferred - Whether the key is deferred

delete_action - Action to perform on deletion

update_action - Action to perform on update

Method Detail

initialise

public void initialise()

Method to initialise the object, setting up all internal arrays. Initialises all sub-objects.

Overrides:

initialise in class MetaData

isDeferred

public final boolean isDeferred()

Accessor for whether the FK is deferred

Returns:

Returns the deferred.

getDeleteAction

public final ForeignKeyAction getDeleteAction()

Accessor for the delete action

Returns:

Returns the deleteAction.

isUnique

public final boolean isUnique()

Accessor for the unique flag

Returns:

Returns the unique.

getUpdateAction

public final ForeignKeyAction getUpdateAction()

Accessor for the update action

Returns:

Returns the updateAction.

toString

public java.lang.String toString(java.lang.String prefix,
                                 java.lang.String indent)

Returns a string representation of the object using a prefix This can be used as part of a facility to output a MetaData file.

Overrides:

toString in class MetaData

Parameters:

prefix - prefix string

indent - indent string

Returns:

a string representation of the object.