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package oracle.toplink.essentials.queryframework;
import java.util.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.expressions.*;
import oracle.toplink.essentials.internal.descriptors.*;
import oracle.toplink.essentials.descriptors.DescriptorQueryManager;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
/**
* <p><b>Purpose</b>:
* Concrete class for all read queries involving a single object.
* <p>
* <p><b>Responsibilities</b>:
* Return a single object for the query.
* Implements the inheritance feature when dealing with abstract descriptors.
*
* @author Yvon Lavoie
* @since TOPLink/Java 1.0
*/
public class ReadObjectQuery extends ObjectLevelReadQuery {
/** Object that can be used in place of a selection criteria. */
protected transient Object selectionObject;
/** Key that can be used in place of a selection criteria. */
protected Vector selectionKey;
/** Can be used to refresh a specific non-cached instance from the database. */
protected boolean shouldLoadResultIntoSelectionObject = false;
/**
* 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.
*/
public ReadObjectQuery() {
super();
}
/**
* 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: {@link #ReadObjectQuery(Class, Call)}, {@link #ReadObjectQuery(Class, Expression)}, {@link #ReadObjectQuery(Class, ExpressionBuilder)}, {@link #ReadObjectQuery(ExpressionBuilder)}, {@link #ReadObjectQuery(Object)}, or {@link #ReadObjectQuery(Object, QueryByExamplePolicy)}.
*/
public ReadObjectQuery(Class classToRead) {
this();
setReferenceClass(classToRead);
}
/**
* PUBLIC:
* Return a new read object query for the class and the selection criteria.
*/
public ReadObjectQuery(Class classToRead, Expression selectionCriteria) {
this();
setReferenceClass(classToRead);
setSelectionCriteria(selectionCriteria);
}
/**
* PUBLIC:
* Return a new read object query for the class.
* The expression builder must be used for all associated expressions used with the query.
*/
public ReadObjectQuery(Class classToRead, ExpressionBuilder builder) {
this();
this.defaultBuilder = builder;
setReferenceClass(classToRead);
}
/**
* PUBLIC:
* Return a new read object query.
* The call represents a database interaction such as SQL, Stored Procedure.
*/
public ReadObjectQuery(Class classToRead, Call call) {
this();
setReferenceClass(classToRead);
setCall(call);
}
/**
* PUBLIC:
* Return a new read object query.
* The call represents a database interaction such as SQL, Stored Procedure.
*/
public ReadObjectQuery(Call call) {
this();
setCall(call);
}
/**
* 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.
*/
public ReadObjectQuery(Object objectToRead) {
this();
setSelectionObject(objectToRead);
}
/**
* PUBLIC:
* The expression builder should be provide on creation to ensure only one is used.
*/
public ReadObjectQuery(ExpressionBuilder builder) {
this();
this.defaultBuilder = builder;
}
/**
* 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 #setCacheUsage(int)
*/
public void checkCacheByExactPrimaryKey() {
setCacheUsage(CheckCacheByExactPrimaryKey);
}
/**
* 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 #setCacheUsage(int)
*/
public void checkCacheByPrimaryKey() {
setCacheUsage(CheckCacheByPrimaryKey);
}
/**
* 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 #setCacheUsage(int)
*/
public void checkCacheThenDatabase() {
setCacheUsage(CheckCacheThenDatabase);
}
/**
* INTERNAL:
* Ensure that the descriptor has been set.
*/
public void checkDescriptor(AbstractSession session) throws QueryException {
if (getReferenceClass() == null) {
throw QueryException.referenceClassMissing(this);
}
if (getDescriptor() == null) {
ClassDescriptor referenceDescriptor;
//Bug#3947714 In case getSelectionObject() is proxy
if (getSelectionObject() != null && session.getProject().hasProxyIndirection()) {
referenceDescriptor = session.getDescriptor(getSelectionObject());
} else {
referenceDescriptor = session.getDescriptor(getReferenceClass());
}
if (referenceDescriptor == null) {
throw QueryException.descriptorIsMissing(getReferenceClass(), this);
}
setDescriptor(referenceDescriptor);
}
}
/**
* INTERNAL:
* The cache check is done before the prepare as a hit will not require the work to be done.
*/
protected Object checkEarlyReturnImpl(AbstractSession session, AbstractRecord translationRow) {
// Do a cache lookup
if (shouldMaintainCache() && (!shouldRefreshIdentityMapResult()) && (!(shouldCheckDescriptorForCacheUsage() && getDescriptor().shouldDisableCacheHits())) && (shouldCheckCache())) {
Object cachedObject = getQueryMechanism().checkCacheForObject(translationRow, session);
// Optimization: If find deleted object by exact primary
// key expression or selection object/key just abort.
if (cachedObject == InvalidObject.instance) {
return cachedObject;
}
if (cachedObject != null) {
if (shouldLoadResultIntoSelectionObject()) {
ObjectBuilder builder = getDescriptor().getObjectBuilder();
builder.copyInto(cachedObject, getSelectionObject());
//put this object into the cache. This may cause some loss of identity
session.getIdentityMapAccessorInstance().putInIdentityMap(getSelectionObject());
cachedObject = getSelectionObject();
}
// check locking. If clone has not been locked, do not early return cached object
if (isLockQuery() && (session.isUnitOfWork() && !((UnitOfWorkImpl)session).isPessimisticLocked(cachedObject))) {
return null;
}
}
if (shouldUseWrapperPolicy()) {
cachedObject = getDescriptor().getObjectBuilder().wrapObject(cachedObject, session);
}
return cachedObject;
} else {
return null;
}
}
/**
* INTERNAL:
* Check to see if a custom query should be used for this query.
* This is done before the query is copied and prepared/executed.
* null means there is none.
*/
protected DatabaseQuery checkForCustomQuery(AbstractSession session, AbstractRecord translationRow) {
checkDescriptor(session);
// check if user defined a custom query in the query manager
if (!isUserDefined()) {
if (isCallQuery()) {
// this is a hand-coded (custom SQL, SDK etc.) call
return null;
}
DescriptorQueryManager descriptorQueryManager = getDescriptor().getQueryManager();
// By default all descriptors have a custom ("static") read-object query.
// This allows the read-object query and SQL to be prepare once.
if (descriptorQueryManager.hasReadObjectQuery()) {
// If the query require special SQL generation or execution do not use the static read object query.
// PERF: the read-object query should always be static to ensure no regeneration of SQL.
if (getJoinedAttributeManager().hasJoinedAttributeExpressions() || hasPartialAttributeExpressions() || hasAsOfClause() || hasNonDefaultFetchGroup() || (!wasDefaultLockMode()) || (!shouldIgnoreBindAllParameters())) {
return null;
}
if ((getSelectionKey() != null) || (getSelectionObject() != null)) {// Must be primary key.
return descriptorQueryManager.getReadObjectQuery();
}
if (getSelectionCriteria() != null) {
AbstractRecord primaryKeyRow = getDescriptor().getObjectBuilder().extractPrimaryKeyRowFromExpression(getSelectionCriteria(), translationRow, session);
// Only execute the query if the selection criteria has the primary key fields set
if (primaryKeyRow != null) {
return descriptorQueryManager.getReadObjectQuery();
}
}
}
}
return null;
}
/**
* INTERNAL:
* Conform the result in the UnitOfWork.
*/
protected Object conformResult(Object result, UnitOfWorkImpl unitOfWork, AbstractRecord databaseRow, boolean buildDirectlyFromRows) {
// Note that if the object does not conform even though other objects might exist on the database null is returned.
// Note that new objects is checked before the read is executed so does not have to be re-checked.
// Must unwrap as the built object is always wrapped.
// Note the object is unwrapped on the parent which it belongs to, as we
// do not want to trigger a registration just yet.
Object implementation = null;
if (buildDirectlyFromRows) {
implementation = result;
} else {
implementation = getDescriptor().getObjectBuilder().unwrapObject(result, unitOfWork.getParent());
}
Expression selectionCriteriaClone = null;
if ((getSelectionCriteria() != null) && (getSelectionKey() == null) && (getSelectionObject() == null)) {
selectionCriteriaClone = (Expression)getSelectionCriteria().clone();
selectionCriteriaClone.getBuilder().setSession(unitOfWork.getRootSession(null));
selectionCriteriaClone.getBuilder().setQueryClass(getReferenceClass());
}
Object clone = conformIndividualResult(implementation, unitOfWork, databaseRow, selectionCriteriaClone, null, buildDirectlyFromRows);
if (clone == null) {
return clone;
}
if (shouldUseWrapperPolicy()) {
return getDescriptor().getObjectBuilder().wrapObject(clone, unitOfWork);
} else {
return clone;
}
}
/**
* 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.
* <p>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.
*/
public void dontLoadResultIntoSelectionObject() {
setShouldLoadResultIntoSelectionObject(false);
}
/**
* INTERNAL:
* Execute the query.
* Do a cache lookup and build object from row if required.
* @exception DatabaseException - an error has occurred on the database
* @return object - the first object found or null if none.
*/
protected Object executeObjectLevelReadQuery() throws DatabaseException {
AbstractRecord row = null;
// If using -m joins, must select all rows.
if (getJoinedAttributeManager().isToManyJoin()) {
List rows = getQueryMechanism().selectAllRows();
if (rows.size() > 0) {
row = (AbstractRecord)rows.get(0);
}
getJoinedAttributeManager().setDataResults(rows, getSession());
} else {
row = getQueryMechanism().selectOneRow();
}
setExecutionTime(System.currentTimeMillis());
Object result = null;
if (getSession().isUnitOfWork()) {
result = registerResultInUnitOfWork(row, (UnitOfWorkImpl)getSession(), getTranslationRow(), true);
} else {
if (row != null) {
result = buildObject(row);
}
}
if (shouldIncludeData()) {
ComplexQueryResult complexResult = new ComplexQueryResult();
complexResult.setResult(result);
complexResult.setData(row);
return complexResult;
}
return result;
}
/**
* 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.
*/
public Vector getSelectionKey() {
return selectionKey;
}
/**
* 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.
*/
public Object getSelectionObject() {
return selectionObject;
}
/**
* PUBLIC:
* Return if this is a read object query.
*/
public boolean isReadObjectQuery() {
return true;
}
/**
* 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.
* <p>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.
*/
public void loadResultIntoSelectionObject() {
setShouldLoadResultIntoSelectionObject(true);
}
/**
* INTERNAL:
* Prepare the receiver for execution in a session.
*/
protected void prepare() throws QueryException {
super.prepare();
if ((getSelectionKey() != null) || (getSelectionObject() != null)) {
// The expression is set in the prepare as params.
setSelectionCriteria(getDescriptor().getObjectBuilder().getPrimaryKeyExpression());
// For bug 2989998 the translation row is required to be set at this point.
if (!shouldPrepare()) {
if (getSelectionKey() != null) {
// Row must come from the key.
setTranslationRow(getDescriptor().getObjectBuilder().buildRowFromPrimaryKeyValues(getSelectionKey(), getSession()));
} else {//(getSelectionObject() != null)
setTranslationRow(getDescriptor().getObjectBuilder().buildRowForTranslation(getSelectionObject(), getSession()));
}
}
}
// If using -m joining select all rows.
if (getJoinedAttributeManager().isToManyJoin()) {
getQueryMechanism().prepareSelectAllRows();
} else {
getQueryMechanism().prepareSelectOneRow();
}
}
/**
* INTERNAL:
* Set the properties needed to be cascaded into the custom query inlucding the translation row.
*/
protected void prepareCustomQuery(DatabaseQuery customQuery) {
ReadObjectQuery customReadQuery = (ReadObjectQuery)customQuery;
customReadQuery.setShouldRefreshIdentityMapResult(shouldRefreshIdentityMapResult());
customReadQuery.setCascadePolicy(getCascadePolicy());
customReadQuery.setShouldMaintainCache(shouldMaintainCache());
customReadQuery.setShouldUseWrapperPolicy(shouldUseWrapperPolicy());
// CR... was missing some values, execution could cause infinite loop.
customReadQuery.setQueryId(getQueryId());
customReadQuery.setExecutionTime(getExecutionTime());
customReadQuery.setShouldLoadResultIntoSelectionObject(shouldLoadResultIntoSelectionObject());
AbstractRecord primaryKeyRow;
if (getSelectionObject() != null) {
// CR#... Must also set the selection object as may be loading into the object (refresh)
customReadQuery.setSelectionObject(getSelectionObject());
// The translation/primary key row will be set in prepareForExecution.
} else if (getSelectionKey() != null) {
customReadQuery.setSelectionKey(getSelectionKey());
} else {
// The primary key row must be used.
primaryKeyRow = customQuery.getDescriptor().getObjectBuilder().extractPrimaryKeyRowFromExpression(getSelectionCriteria(), customQuery.getTranslationRow(), customReadQuery.getSession());
customReadQuery.setTranslationRow(primaryKeyRow);
}
}
/**
* INTERNAL:
* Prepare the receiver for execution in a session.
*/
public void prepareForExecution() throws QueryException {
super.prepareForExecution();
// For bug 2989998 the translation row now sometimes set earlier in prepare.
if (shouldPrepare()) {
if (getSelectionKey() != null) {
// Row must come from the key.
setTranslationRow(getDescriptor().getObjectBuilder().buildRowFromPrimaryKeyValues(getSelectionKey(), getSession()));
} else if (getSelectionObject() != null) {
// The expression is set in the prepare as params.
setTranslationRow(getDescriptor().getObjectBuilder().buildRowForTranslation(getSelectionObject(), getSession()));
}
}
}
/**
* INTERNAL:
* All objects queried via a UnitOfWork get registered here. If the query
* went to the database.
* <p>
* Involves registering the query result individually and in totality, and
* hence refreshing / conforming is done here.
* @param result may be collection (read all) or an object (read one),
* or even a cursor. If in transaction the shared cache will
* be bypassed, meaning the result may not be originals from the parent
* but raw database rows.
* @param unitOfWork the unitOfWork the result is being registered in.
* @param arguments the original arguments/parameters passed to the query
* execution. Used by conforming
* @param buildDirectlyFromRows If in transaction must construct
* a registered result from raw database rows.
* @return the final (conformed, refreshed, wrapped) UnitOfWork query result
*/
public Object registerResultInUnitOfWork(Object result, UnitOfWorkImpl unitOfWork, AbstractRecord arguments, boolean buildDirectlyFromRows) {
if (result == null) {
return null;
}
if (shouldConformResultsInUnitOfWork() || getDescriptor().shouldAlwaysConformResultsInUnitOfWork()) {
return conformResult(result, unitOfWork, arguments, buildDirectlyFromRows);
}
Object clone = registerIndividualResult(result, unitOfWork, buildDirectlyFromRows, null);
if (shouldUseWrapperPolicy()) {
clone = getDescriptor().getObjectBuilder().wrapObject(clone, unitOfWork);
}
return clone;
}
/**
* 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.
*/
public void setSelectionKey(Vector selectionKey) {
this.selectionKey = selectionKey;
setIsPrepared(false);
}
/**
* 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.
*/
public void setSelectionObject(Object selectionObject) {
if (selectionObject == null) {
throw QueryException.selectionObjectCannotBeNull(this);
}
setSelectionKey(null);
// setIsPrepared(false) triggered by previous.
setReferenceClass(selectionObject.getClass());
this.selectionObject = selectionObject;
}
/**
* 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.
* <p>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.
*/
public void setShouldLoadResultIntoSelectionObject(boolean shouldLoadResultIntoSelectionObject) {
this.shouldLoadResultIntoSelectionObject = shouldLoadResultIntoSelectionObject;
}
/**
* PUBLIC:
* The primary key can be specified if used instead of an expression or selection object.
*/
public void setSingletonSelectionKey(Object selectionKey) {
Vector key = new Vector();
key.addElement(selectionKey);
setSelectionKey(key);
}
/**
* PUBLIC:
* Return if the cache should be checked.
*/
public boolean shouldCheckCache() {
return getCacheUsage() != DoNotCheckCache;
}
/**
* PUBLIC:
* Return if cache should be checked.
*/
public boolean shouldCheckCacheByExactPrimaryKey() {
return getCacheUsage() == CheckCacheByExactPrimaryKey;
}
/**
* PUBLIC:
* Return if cache should be checked.
*/
public boolean shouldCheckCacheByPrimaryKey() {
return (getCacheUsage() == CheckCacheByPrimaryKey) || (getCacheUsage() == UseDescriptorSetting);
}
/**
* PUBLIC:
* Return if cache should be checked.
*/
public boolean shouldCheckCacheThenDatabase() {
return getCacheUsage() == CheckCacheThenDatabase;
}
/**
* PUBLIC:
* return true if the result should be loaded into the passed in selection Object
*/
public boolean shouldLoadResultIntoSelectionObject() {
return shouldLoadResultIntoSelectionObject;
}
/**
* INTERNAL:
* Return if the query has an non-default fetch group defined for itself.
*/
protected boolean hasNonDefaultFetchGroup() {
return getDescriptor().hasFetchGroupManager() && ((this.getFetchGroup() != null) || (this.getFetchGroupName() != null) || (!this.shouldUseDefaultFetchGroup()));
}
}
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