oracle.toplink.queryframework
Class ReadObjectQuery

java.lang.Object
oracle.toplink.queryframework.DatabaseQuery
oracle.toplink.queryframework.ReadQuery
oracle.toplink.queryframework.ObjectLevelReadQuery
oracle.toplink.queryframework.ReadObjectQuery

All Implemented Interfaces:

java.lang.Cloneable, oracle.toplink.internal.helper.FalseUndefinedTrue, java.io.Serializable

public class ReadObjectQuery

extends ObjectLevelReadQuery

Purpose: Concrete class for all read queries involving a single object.

Responsibilities: Return a single object for the query. Implements the inheritance feature when dealing with abstract descriptors.

Since:

TOPLink/Java 1.0

See Also:

Serialized Form

Field Summary

Fields inherited from class oracle.toplink.queryframework.ObjectLevelReadQuery

CheckCacheByExactPrimaryKey, CheckCacheByPrimaryKey, CheckCacheOnly, CheckCacheThenDatabase, ConformResultsInUnitOfWork, DoNotCheckCache, DONT_USE_DISTINCT, inMemoryQueryIndirectionPolicy, LOCK, LOCK_NOWAIT, NO_LOCK, UNCOMPUTED_DISTINCT, USE_DISTINCT

Fields inherited from class oracle.toplink.queryframework.DatabaseQuery

CascadeAggregateDelete, CascadeAllParts, CascadeDependentParts, CascadePrivateParts, NoCascading, QUERY_PREPARE

Fields inherited from interface oracle.toplink.internal.helper.FalseUndefinedTrue

False, True, Undefined

Constructor Summary

ReadObjectQuery()
PUBLIC: Return a new read object query.

ReadObjectQuery(java.lang.Class classToRead)
PUBLIC: Return a new read object query.

ReadObjectQuery(java.lang.Class classToRead, Call call)
PUBLIC: Return a new read object query.

ReadObjectQuery(java.lang.Class classToRead, Expression selectionCriteria)
PUBLIC: Return a new read object query for the class and the selection criteria.

ReadObjectQuery(java.lang.Class classToRead, ExpressionBuilder builder)
PUBLIC: Return a new read object query for the class.

ReadObjectQuery(ExpressionBuilder builder)
PUBLIC: The expression builder should be provide on creation to ensure only one is used.

ReadObjectQuery(java.lang.Object objectToRead)
PUBLIC: Return a query to read the object with the same primary key as the provided object.

ReadObjectQuery(java.lang.Object exampleObject, QueryByExamplePolicy policy)
PUBLIC: Return a query by example query to find an object matching the attributes of the example object.

Method Summary

void	checkCache() Deprecated. replaced by checkCacheByPrimaryKey
void	checkCacheByExactPrimaryKey() PUBLIC: The cache will be checked only if the query contains exactly the primary key.
void	checkCacheByPrimaryKey() PUBLIC: This is the default, the cache will be checked only if the query contains the primary key.
void	checkCacheThenDatabase() PUBLIC: The cache will be checked completely, then if the object is not found or the query too complex the database will be queried.
java.lang.Object	checkEarlyReturn(oracle.toplink.publicinterface.Session session, DatabaseRow translationRow) INTERNAL: The cache check is done before the prepare as a hit will not require the work to be done.
void	dontLoadResultIntoSelectionObject() PUBLIC: Do not refesh/load into the selection object, this is the default.
java.lang.Object	execute() INTERNAL: Execute the query.
java.lang.Object	extractRemoteResult(oracle.toplink.internal.remote.Transporter transporter) INTERNAL: Extract the correct query result from the transporter.
java.util.Vector	getSelectionKey() PUBLIC: The primary key can be specified if used instead of an expression or selection object.
java.lang.Object	getSelectionObject() PUBLIC: Return the selection object of the query.
boolean	isReadObjectQuery() PUBLIC: Return if this is a read object query.
void	loadResultIntoSelectionObject() PUBLIC: Allow for the selection object of the query to be refreshed or put into the TopLink cache.
void	prepareForExecution() INTERNAL: Prepare the receiver for execution in a session.
java.lang.Object	registerObjectInUnitOfWork(java.lang.Object object, oracle.toplink.publicinterface.UnitOfWork unitOfWork, DatabaseRow databaseRow) INTERNAL: Register the result in the unit of work, after execution.
oracle.toplink.internal.helper.IdentityHashtable	replaceValueHoldersIn(java.lang.Object object, oracle.toplink.internal.remote.RemoteSessionController controller) INTERNAL: replace the value holders in the specified result object(s)
void	setCheckCache(boolean checkCache) Deprecated. replaced by setCacheUsage
void	setSelectionKey(java.util.Vector selectionKey) PUBLIC: The primary key can be specified if used instead of an expression or selection object.
void	setSelectionObject(java.lang.Object selectionObject) PUBLIC: Used to set the where clause of the query.
void	setShouldLoadResultIntoSelectionObject(boolean shouldLoadResultIntoSelectionObject) PUBLIC: Allow for the selection object of the query to be refreshed or put into the TopLink cache.
void	setSingletonSelectionKey(java.lang.Object selectionKey) PUBLIC: The primary key can be specified if used instead of an expression or selection object.
boolean	shouldCheckCache() PUBLIC: Return if the cache should be checked.
boolean	shouldCheckCacheByExactPrimaryKey() PUBLIC: Return if cache should be checked.
boolean	shouldCheckCacheByPrimaryKey() PUBLIC: Return if cache should be checked.
boolean	shouldCheckCacheThenDatabase() PUBLIC: Return if cache should be checked.
boolean	shouldLoadResultIntoSelectionObject() PUBLIC: return true if the result should be loaded into the passed in selection Object
boolean	shouldMaintainCache(oracle.toplink.publicinterface.Session session) INTERNAL: Return if the cache should be checked or not.

Methods inherited from class oracle.toplink.queryframework.ObjectLevelReadQuery

acquireLocks, acquireLocksWithoutWaiting, addAdditionalField, addAdditionalField, addJoinedAttribute, addJoinedAttribute, addPartialAttribute, addPartialAttribute, buildObject, changeDescriptor, checkCacheOnly, checkDescriptor, conformResultsInUnitOfWork, dontAcquireLocks, dontCheckCache, dontRefreshIdentityMapResult, dontRefreshRemoteIdentityMapResult, dontUseDistinct, getAdditionalFields, getBaseExpression, getCacheUsage, getDistinctState, getExampleObject, getExpressionBuilder, getInMemoryQueryIndirectionPolicy, getJoinedAttributeExpressions, getLeafDescriptorFor, getLeafMappingFor, getLockMode, getPartialAttributeExpressions, getPartialAttributeExpressionsWithoutKeyFields, getQueryByExamplePolicy, getReferenceClass, getSelectionCriteriaForPersistence, hasJoinedAttributes, hasPartialAttributeExpressions, isAttributeJoined, isDistinctComputed, isLockQuery, isObjectLevelReadQuery, isPartialAttribute, refreshIdentityMapResult, refreshRemoteIdentityMapResult, resetDistinct, setAdditionalFields, setBaseExpression, setCacheUsage, setDistinctState, setExampleObject, setInMemoryQueryIndirectionPolicy, setJoinedAttributeExpressions, setLockMode, setPartialAttributeExpressions, setQueryByExamplePolicy, setReferenceClass, setSelectionCriteriaFromPersistence, setShouldIncludeData, setShouldRefreshIdentityMapResult, setShouldRefreshRemoteIdentityMapResult, shouldCheckCacheOnly, shouldConformResultsInUnitOfWork, shouldDistinctBeUsed, shouldIncludeData, shouldReadMapping, shouldRefreshIdentityMapResult, shouldRefreshRemoteIdentityMapResult, toString, useDistinct

Methods inherited from class oracle.toplink.queryframework.ReadQuery

cacheQueryResults, clearQueryResults, doNotCacheQueryResults, execute, getMaxRows, getQueryId, isReadQuery, remoteExecute, setMaxRows, setQueryId, setShouldCacheQueryResults, shouldCacheQueryResults

Methods inherited from class oracle.toplink.queryframework.DatabaseQuery

addArgument, addArgument, addArgument, addArgumentValue, addArgumentValues, addCall, addStatement, bindAllParameters, cacheStatement, cascadeAllParts, cascadeOnlyDependentParts, cascadePrivateParts, checkPrepare, clone, dontBindAllParameters, dontCacheStatement, dontCascadeParts, dontMaintainCache, getAccessor, getArguments, getArgumentTypes, getArgumentValues, getCall, getCascadePolicy, getDescriptor, getEJBQLString, getHintString, getName, getProperties, getProperty, getQueryMechanism, getQueryTimeout, getRedirector, getSelectionCriteria, getSession, getSessionName, getSQLStatement, getSQLString, getTranslatedSQLString, getTranslationRow, hasAccessor, hasProperties, hasSessionName, ignoreBindAllParameters, ignoreCacheStatement, isCallQuery, isCascadeOfAggregateDelete, isDataModifyQuery, isDataReadQuery, isDeleteObjectQuery, isExpressionQuery, isModifyQuery, isObjectLevelModifyQuery, isReadAllQuery, isReportQuery, isSQLCallQuery, isUserDefined, isWriteObjectQuery, maintainCache, prepareCall, redirectQuery, remoteExecute, removeProperty, rowFromArguments, setAccessor, setArguments, setArgumentTypes, setArgumentValues, setCall, setCascadePolicy, setDescriptor, setEJBQLString, setHintString, setIsUserDefined, setName, setProperties, setProperty, setQueryTimeout, setRedirector, setSelectionCriteria, setSession, setSessionName, setShouldBindAllParameters, setShouldCacheStatement, setShouldMaintainCache, setShouldPrepare, setShouldUseWrapperPolicy, setSQLStatement, setSQLString, setTranslationRow, shouldBindAllParameters, shouldCacheStatement, shouldCascadeAllParts, shouldCascadeOnlyDependentParts, shouldCascadeParts, shouldCascadePrivateParts, shouldIgnoreBindAllParameters, shouldIgnoreCacheStatement, shouldIgnoreMaintainCache, shouldMaintainCache, shouldPrepare, shouldUseWrapperPolicy

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadObjectQuery

public ReadObjectQuery()

PUBLIC: Return a new read object query. A reference class must be specified before execution. It is better to provide the class and expression builder on construction to esnure a single expression builder is used. If no selection criteria is specified this will reads the first object found in the database.

ReadObjectQuery

public ReadObjectQuery(java.lang.Class classToRead)

PUBLIC: Return a new read object query. By default, the query has no selection criteria. Executing this query without selection criteria will always result in a database access to read the first instance of the specified Class found in the database. This is true no matter how cache usage is configured and even if an instance of the specified Class exists in the cache. Executing a query with selection criteria allows you to avoid a database access if the selected instance is in the cache. For this reason, you may whish to use a ReadObjectQuery constructor that takes selection criteria, such as: ReadObjectQuery(Class, Call), ReadObjectQuery(Class, Expression), ReadObjectQuery(Class, ExpressionBuilder), ReadObjectQuery(ExpressionBuilder), ReadObjectQuery(Object), or ReadObjectQuery(Object, QueryByExamplePolicy).

ReadObjectQuery

public ReadObjectQuery(java.lang.Class classToRead,
Expression selectionCriteria)

PUBLIC: Return a new read object query for the class and the selection criteria.

ReadObjectQuery

public ReadObjectQuery(java.lang.Class classToRead,
ExpressionBuilder builder)

PUBLIC: Return a new read object query for the class. The expression builder must be used for all associated expressions used with the query.

ReadObjectQuery

public ReadObjectQuery(java.lang.Class classToRead,
Call call)

PUBLIC: Return a new read object query. The call represents a database interaction such as SQL, Stored Procedure.

ReadObjectQuery

public ReadObjectQuery(java.lang.Object objectToRead)

PUBLIC: Return a query to read the object with the same primary key as the provided object. Note: This is not a query by example object, only the primary key will be used for the selection criteria.

ReadObjectQuery

public ReadObjectQuery(java.lang.Object exampleObject,
QueryByExamplePolicy policy)

PUBLIC: Return a query by example query to find an object matching the attributes of the example object.

ReadObjectQuery

public ReadObjectQuery(ExpressionBuilder builder)

PUBLIC: The expression builder should be provide on creation to ensure only one is used.

Method Detail

checkCache

public void checkCache()

Deprecated. replaced by checkCacheByPrimaryKey

OBSOLETE: This can be used to explicitly disable the cache hit. The cache hit may not be desired in some cases, such as stored procedures that accept the primary key but do not query on it.

checkCacheByExactPrimaryKey

public void checkCacheByExactPrimaryKey()

PUBLIC: The cache will be checked only if the query contains exactly the primary key. Queries can be configured to use the cache at several levels. Other caching option are available.

See Also:

ObjectLevelReadQuery.setCacheUsage(int)

checkCacheByPrimaryKey

public void checkCacheByPrimaryKey()

PUBLIC: This is the default, the cache will be checked only if the query contains the primary key. Queries can be configured to use the cache at several levels. Other caching option are available.

See Also:

ObjectLevelReadQuery.setCacheUsage(int)

checkCacheThenDatabase

public void checkCacheThenDatabase()

PUBLIC: The cache will be checked completely, then if the object is not found or the query too complex the database will be queried. Queries can be configured to use the cache at several levels. Other caching option are available.

See Also:

ObjectLevelReadQuery.setCacheUsage(int)

checkEarlyReturn

public java.lang.Object checkEarlyReturn(oracle.toplink.publicinterface.Session session,
DatabaseRow translationRow)

INTERNAL: The cache check is done before the prepare as a hit will not require the work to be done.

Overrides:

checkEarlyReturn in class DatabaseQuery

shouldMaintainCache

public boolean shouldMaintainCache(oracle.toplink.publicinterface.Session session)

INTERNAL: Return if the cache should be checked or not.

dontLoadResultIntoSelectionObject

public void dontLoadResultIntoSelectionObject()

PUBLIC: Do not refesh/load into the selection object, this is the default. This property allows for the selection object of the query to be refreshed or put into the TopLink cache. By default on a read or refresh the object in the cache is refreshed and returned or a new object is built from the database, in some cases such as EJB BMP it is desirable to refresh or load into the object passed into the read object query.

Note: This forces the selection object into the cache a replaces any existing object that may already be there, this is a strict violation of object identity and other objects can still be refering to the old object.

execute

public java.lang.Object execute()
                         throws DatabaseException

INTERNAL: Execute the query. Do a cache lookup and build object from row if required.

Specified by:

execute in class DatabaseQuery

Returns:

object - the first object found or null if none.

Throws:

DatabaseException - - an error has occurred on the database

extractRemoteResult

public java.lang.Object extractRemoteResult(oracle.toplink.internal.remote.Transporter transporter)

INTERNAL: Extract the correct query result from the transporter.

Overrides:

extractRemoteResult in class DatabaseQuery

getSelectionKey

public java.util.Vector getSelectionKey()

PUBLIC: The primary key can be specified if used instead of an expression or selection object. If composite the primary must be in the same order as defined in the descriptor.

getSelectionObject

public java.lang.Object getSelectionObject()

PUBLIC: Return the selection object of the query. This can be used instead of a where clause expression for single object primary key queries. The selection object given should have a primary key defined, this primary key will be used to query the database instance of the same object. This is a basic form of query by example where only the primary key is required, it can be used for simple query forms, or testing.

isReadObjectQuery

public boolean isReadObjectQuery()

PUBLIC: Return if this is a read object query.

Overrides:

isReadObjectQuery in class DatabaseQuery

loadResultIntoSelectionObject

public void loadResultIntoSelectionObject()

PUBLIC: Allow for the selection object of the query to be refreshed or put into the TopLink cache. By default on a read or refresh the object in the cache is refreshed and returned or a new object is built from the database, in some cases such as EJB BMP it is desirable to refresh or load into the object passed into the read object query.

Note: This forces the selection object into the cache a replaces any existing object that may already be there, this is a strict violation of object identity and other objects can still be refering to the old object.

prepareForExecution

public void prepareForExecution()
                         throws QueryException

INTERNAL: Prepare the receiver for execution in a session.

Overrides:

prepareForExecution in class DatabaseQuery

Throws:

QueryException

registerObjectInUnitOfWork

public java.lang.Object registerObjectInUnitOfWork(java.lang.Object object,
                                                   oracle.toplink.publicinterface.UnitOfWork unitOfWork,
DatabaseRow databaseRow)

INTERNAL: Register the result in the unit of work, after execution. The return value (clone) from register it returned to the user. If refreshing is used the object is reverted from the parent.

Specified by:

registerObjectInUnitOfWork in class ObjectLevelReadQuery

replaceValueHoldersIn

public oracle.toplink.internal.helper.IdentityHashtable replaceValueHoldersIn(java.lang.Object object,
                                                                              oracle.toplink.internal.remote.RemoteSessionController controller)

INTERNAL: replace the value holders in the specified result object(s)

Overrides:

replaceValueHoldersIn in class DatabaseQuery

setCheckCache

public void setCheckCache(boolean checkCache)

Deprecated. replaced by setCacheUsage

OBSOLETE: This can be used to explicitly disable the cache hit. The cache hit may not be desired in some cases, such as stored procedures that accept the primary key but do not query on it.

setSelectionKey

public void setSelectionKey(java.util.Vector selectionKey)

PUBLIC: The primary key can be specified if used instead of an expression or selection object. If composite the primary must be in the same order as defined in the descriptor.

setSelectionObject

public void setSelectionObject(java.lang.Object selectionObject)

PUBLIC: Used to set the where clause of the query. This can be used instead of a where clause expression for single object primary key queries. The selection object given should have a primary key defined, this primary key will be used to query the database instance of the same object. This is a basic form of query by example where only the primary key is required, it can be used for simple query forms, or testing.

setShouldLoadResultIntoSelectionObject

public void setShouldLoadResultIntoSelectionObject(boolean shouldLoadResultIntoSelectionObject)

PUBLIC: Allow for the selection object of the query to be refreshed or put into the TopLink cache. By default on a read or refresh the object in the cache is refreshed and returned or a new object is built from the database, in some cases such as EJB BMP it is desirable to refresh or load into the object passed into the read object query.

Note: This forces the selection object into the cache a replaces any existing object that may already be there, this is a strict violation of object identity and other objects can still be refering to the old object.

setSingletonSelectionKey

public void setSingletonSelectionKey(java.lang.Object selectionKey)

PUBLIC: The primary key can be specified if used instead of an expression or selection object.

shouldCheckCache

public boolean shouldCheckCache()

PUBLIC: Return if the cache should be checked.

shouldCheckCacheByExactPrimaryKey

public boolean shouldCheckCacheByExactPrimaryKey()

PUBLIC: Return if cache should be checked.

shouldCheckCacheByPrimaryKey

public boolean shouldCheckCacheByPrimaryKey()

PUBLIC: Return if cache should be checked.

shouldCheckCacheThenDatabase

public boolean shouldCheckCacheThenDatabase()

PUBLIC: Return if cache should be checked.

shouldLoadResultIntoSelectionObject

public boolean shouldLoadResultIntoSelectionObject()

PUBLIC: return true if the result should be loaded into the passed in selection Object