org.datanucleus.store.rdbms.scostore

Class ElementContainerStore

java.lang.Object

org.datanucleus.store.rdbms.scostore.BaseContainerStore

org.datanucleus.store.rdbms.scostore.ElementContainerStore

All Implemented Interfaces:

org.datanucleus.store.scostore.Store

Direct Known Subclasses:

AbstractArrayStore, AbstractCollectionStore

public abstract class ElementContainerStore
extends BaseContainerStore

Representation of the store of an element-based container. This is used to represent either a collection or an array. There are the following types of situation that we try to cater for with respect to elements.

• element-type is PC with "new-table" or "superclass-table" inheritance. In this case we will have elementInfo with 1 entry.
• element-type is PC with "subclass-table" inheritance. In this case we will have elementInfo with "n" entries (1 for each subclass type with its own table). We also have emd being the MetaData for the element-type.
• element-type is Reference type. In this case we will have elementInfo with "n" entries (1 for each implementation type).
• element-type is non-PC. In this case we have no elementInfo and no emd

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ElementContainerStore.ElementInfo Inner class wrapping the information required for a valid element type.

Field Summary

Fields

Modifier and Type	Field and Description
protected String	addStmt Statement for adding an element to the container.
protected String	clearStmt Statement for clearing the container.
protected Table	containerTable Table containing the link between owner and element.
protected ElementContainerStore.ElementInfo[]	elementInfo Information for the elements of this container.
protected boolean	elementIsPersistentInterface Whether the element is of a persistent-interface (defined using "{interface}") type.
protected JavaTypeMapping	elementMapping Mapping for the element.
protected boolean	elementsAreEmbedded Whether the elements are embedded.
protected boolean	elementsAreSerialised Whether the elements are serialised.
protected String	elementType Type of the element.
protected org.datanucleus.metadata.AbstractClassMetaData	emd MetaData for the "element-type" class.
protected boolean	iterateUsingDiscriminator Flag to set whether the iterator statement will use a discriminator or not.
protected JavaTypeMapping	orderMapping Mapping for an ordering column to allow for duplicates in the container.
protected JavaTypeMapping	relationDiscriminatorMapping Optional mapping to distinguish elements of one collection from another when sharing the join table.
protected String	relationDiscriminatorValue Value to use to discriminate between elements of this collection from others using the same join table.
protected String	removeStmt Statement for removing an element from the container.
protected String	sizeStmt Statement for getting the size of the container.
protected boolean	usingDiscriminatorInSizeStmt Whether we are using a discriminator in the "size" statement.

Fields inherited from class org.datanucleus.store.rdbms.scostore.BaseContainerStore

allowNulls, clr, dba, ownerMapping, ownerMemberMetaData, relationType, storeMgr

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ElementContainerStore(RDBMSStoreManager storeMgr, org.datanucleus.ClassLoaderResolver clr) Constructor.

Method Summary

Modifier and Type	Method and Description
void	clear(org.datanucleus.state.ObjectProvider ownerOP) Clear the association from owner to all elements.
void	executeClear(org.datanucleus.state.ObjectProvider ownerOP)
protected String	getAddStmtForJoinTable() Generates the statement for adding items.
protected String	getClearStmt() Generate statement for clearing the container.
Table	getContainerTable()
ElementContainerStore.ElementInfo[]	getElementInfo()
protected ElementContainerStore.ElementInfo[]	getElementInformationForClass() Convenience method to find the element information relating to the element type.
JavaTypeMapping	getElementMapping()
org.datanucleus.metadata.AbstractClassMetaData	getEmd()
JavaTypeMapping	getOrderMapping()
JavaTypeMapping	getRelationDiscriminatorMapping()
String	getRelationDiscriminatorValue()
int	getSize(org.datanucleus.state.ObjectProvider ownerOP)
protected String	getSizeStmt() Generate statement for getting the size of thecontainer.
boolean	hasOrderMapping() Accessor for whether the store has an order mapping, to allow for duplicates or ordering.
protected void	invalidateAddStmt() Method to remove any stored statement for addition of an element.
boolean	isElementsAreEmbedded()
boolean	isElementsAreSerialised()
abstract Iterator	iterator(org.datanucleus.state.ObjectProvider ownerOP) Accessor for an iterator through the container elements.
int	size(org.datanucleus.state.ObjectProvider op) Method to return the size of the container.
protected boolean	validateElementForReading(org.datanucleus.state.ObjectProvider op, Object element) Method to check if an element is already persistent or is persistent but managed by a different persistence manager.
protected boolean	validateElementForWriting(org.datanucleus.ExecutionContext ec, Object element, org.datanucleus.store.FieldValues fieldValues) Method to check if an element is already persistent, or is managed by a different Persistencemanager.
protected boolean	validateElementType(org.datanucleus.ClassLoaderResolver clr, Object element) Method to validate an element against the accepted type.

Methods inherited from class org.datanucleus.store.rdbms.scostore.BaseContainerStore

allowsBatching, getDatastoreAdapter, getObjectProviderForEmbeddedPCObject, getOwnerMapping, getOwnerMemberMetaData, getRelationType, getStoreManager, isEmbeddedMapping, setOwner

Methods inherited from class java.lang.Object

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

Field Detail

iterateUsingDiscriminator

protected boolean iterateUsingDiscriminator

Flag to set whether the iterator statement will use a discriminator or not.

sizeStmt

protected String sizeStmt

Statement for getting the size of the container.

clearStmt

protected String clearStmt

Statement for clearing the container.

addStmt

protected String addStmt

Statement for adding an element to the container.

removeStmt

protected String removeStmt

Statement for removing an element from the container.

usingDiscriminatorInSizeStmt

protected boolean usingDiscriminatorInSizeStmt

Whether we are using a discriminator in the "size" statement.

elementInfo

protected ElementContainerStore.ElementInfo[] elementInfo

Information for the elements of this container. When the "element-type" table is new-table, or superclass-table then there is 1 value here. When the "element-type" table uses subclass-table, or when it is a reference type then there can be multiple.

emd

protected org.datanucleus.metadata.AbstractClassMetaData emd

MetaData for the "element-type" class. Not used for reference types since no metadata is present for the declared type.

containerTable

protected Table containerTable

Table containing the link between owner and element. Not set when using FK relations.

elementMapping

protected JavaTypeMapping elementMapping

Mapping for the element.

elementType

protected String elementType

Type of the element.

elementsAreEmbedded

protected boolean elementsAreEmbedded

Whether the elements are embedded.

elementsAreSerialised

protected boolean elementsAreSerialised

Whether the elements are serialised.

elementIsPersistentInterface

protected boolean elementIsPersistentInterface

Whether the element is of a persistent-interface (defined using "{interface}") type.

orderMapping

protected JavaTypeMapping orderMapping

Mapping for an ordering column to allow for duplicates in the container. Can also be used for ordering elements in a List/array. Can also be used where we have an embedded object and so need to form the PK with something.

relationDiscriminatorMapping

protected JavaTypeMapping relationDiscriminatorMapping

Optional mapping to distinguish elements of one collection from another when sharing the join table.

relationDiscriminatorValue

protected String relationDiscriminatorValue

Value to use to discriminate between elements of this collection from others using the same join table.

Constructor Detail

ElementContainerStore

protected ElementContainerStore(RDBMSStoreManager storeMgr,
                                org.datanucleus.ClassLoaderResolver clr)

Constructor.

Parameters:

storeMgr - Manager for the store

clr - ClassLoader resolver

Method Detail

getElementInfo

public ElementContainerStore.ElementInfo[] getElementInfo()

getElementMapping

public JavaTypeMapping getElementMapping()

getOrderMapping

public JavaTypeMapping getOrderMapping()

getRelationDiscriminatorMapping

public JavaTypeMapping getRelationDiscriminatorMapping()

getRelationDiscriminatorValue

public String getRelationDiscriminatorValue()

getContainerTable

public Table getContainerTable()

getEmd

public org.datanucleus.metadata.AbstractClassMetaData getEmd()

isElementsAreSerialised

public boolean isElementsAreSerialised()

isElementsAreEmbedded

public boolean isElementsAreEmbedded()

getElementInformationForClass

protected ElementContainerStore.ElementInfo[] getElementInformationForClass()

Convenience method to find the element information relating to the element type. Used specifically for the "element-type" of a collection/array to find the elements which have table information. Not used for reference types.

Returns:

Element information relating to the element type

hasOrderMapping

public boolean hasOrderMapping()

Accessor for whether the store has an order mapping, to allow for duplicates or ordering.

Returns:

Whether an order mapping is present.

validateElementType

protected boolean validateElementType(org.datanucleus.ClassLoaderResolver clr,
                                      Object element)

Method to validate an element against the accepted type.

Parameters:

clr - The ClassLoaderResolver

element - The element to validate

Returns:

Whether it is valid.

validateElementForReading

protected boolean validateElementForReading(org.datanucleus.state.ObjectProvider op,
                                            Object element)

Method to check if an element is already persistent or is persistent but managed by a different persistence manager.

Parameters:

op - The ObjectProvider of this owner

element - The element

Returns:

Whether it is valid for reading.

validateElementForWriting

protected boolean validateElementForWriting(org.datanucleus.ExecutionContext ec,
                                            Object element,
                                            org.datanucleus.store.FieldValues fieldValues)

Method to check if an element is already persistent, or is managed by a different Persistencemanager. If not persistent, this will persist it.

Parameters:

ec - execution context

element - The element

fieldValues - any initial field values to use if persisting the element

Returns:

Whether the element was persisted during this call

iterator

public abstract Iterator iterator(org.datanucleus.state.ObjectProvider ownerOP)

Accessor for an iterator through the container elements.

Parameters:

ownerOP - ObjectProvider for the container.

Returns:

The Iterator

clear

public void clear(org.datanucleus.state.ObjectProvider ownerOP)

Clear the association from owner to all elements. Provides cascade-delete when the elements being deleted are PC types.

Parameters:

ownerOP - ObjectProvider for the container.

size

public int size(org.datanucleus.state.ObjectProvider op)

Method to return the size of the container.

Parameters:

op - The ObjectProvider.

Returns:

The size.

invalidateAddStmt

protected void invalidateAddStmt()

Method to remove any stored statement for addition of an element.

getAddStmtForJoinTable

protected String getAddStmtForJoinTable()

Generates the statement for adding items. The EMBEDDEDFIELDX columns are only added for embedded PC elements.

 INSERT INTO COLLTABLE (OWNERCOL,[ELEMENTCOL],[EMBEDDEDFIELD1, EMBEDDEDFIELD2,...],[ORDERCOL]) VALUES (?,?,?)
 

Returns:

The Statement for adding an item

executeClear

public void executeClear(org.datanucleus.state.ObjectProvider ownerOP)

getClearStmt

protected String getClearStmt()

Generate statement for clearing the container.

 DELETE FROM CONTAINERTABLE WHERE OWNERCOL = ? [AND RELATION_DISCRIM=?]
 

TODO Add a discriminator restriction on this statement so we only clear ones with a valid discriminator value

Returns:

Statement for clearing the container.

getSize

public int getSize(org.datanucleus.state.ObjectProvider ownerOP)

getSizeStmt

protected String getSizeStmt()

Generate statement for getting the size of thecontainer. The order part is only present when an order mapping is used. The discriminator part is only present when the element has a discriminator.

 SELECT COUNT(*) FROM TBL THIS
 [INNER JOIN ELEM_TBL ELEM ON TBL.COL = ELEM.ID] - when no null
 [LEFT OUTER JOIN ELEM_TBL ELEM ON TBL.COL = ELEM.ID] - when allows null
 WHERE THIS.OWNERCOL=?
 [AND THIS.ORDERCOL IS NOT NULL]
 [AND (DISCRIMINATOR=? OR DISCRMINATOR=? OR DISCRIMINATOR=? [OR DISCRIMINATOR IS NULL])]
 [AND RELATION_DISCRIM=?]
 

The discriminator part includes all subclasses of the element type. If the element is in a different table to the container then an INNER JOIN will be present to link the two tables, and table aliases will be present also. TODO Update this to allow for getting the size when more than 1 element table.

Returns:

The Statement returning the size of the container.