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package oracle.toplink.essentials.queryframework;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
/**
* <p><b>Purpose</b>:
* Used for inserting or updating objects
* WriteObjectQuery determines whether to perform a insert or an update on the database.
*
* <p><b>Responsibilities</b>:
* <ul>
* <li> Determines whether to perform a insert or an update on the database.
* <li> Stores object in identity map for insert if required.
* </ul>
*
* @author Yvon Lavoie
* @since TOPLink/Java 1.0
*/
public class WriteObjectQuery extends ObjectLevelModifyQuery {
public WriteObjectQuery() {
super();
}
public WriteObjectQuery(Object objectToWrite) {
this();
setObject(objectToWrite);
}
public WriteObjectQuery(Call call) {
this();
setCall(call);
}
/**
* INTERNAL:
* Return if the object exists on the database or not.
* This first checks existence in the chache, then on the database.
*/
protected boolean doesObjectExist() {
boolean doesExist;
if (getSession().isUnitOfWork()) {
doesExist = !((UnitOfWorkImpl)getSession()).isCloneNewObject(getObject());
if (doesExist) {
doesExist = ((UnitOfWorkImpl)getSession()).isObjectRegistered(getObject());
}
} else {
//Initialize does exist query
DoesExistQuery existQuery = (DoesExistQuery)getDescriptor().getQueryManager().getDoesExistQuery().clone();
existQuery.setObject(getObject());
existQuery.setPrimaryKey(getPrimaryKey());
existQuery.setDescriptor(getDescriptor());
existQuery.setTranslationRow(getTranslationRow());
doesExist = ((Boolean)getSession().executeQuery(existQuery)).booleanValue();
}
return doesExist;
}
/**
* INTERNAL:
* Perform a does exist check to decide whether to perform an insert or update and
* delegate the work to the mechanism. Does exists check will also perform an
* optimistic lock check if required.
* @exception DatabaseException - an error has occurred on the database
* @exception OptimisticLockException - an error has occurred using the optimistic lock feature
* @return object - the object being written.
*/
public Object executeDatabaseQuery() throws DatabaseException, OptimisticLockException {
if (getObjectChangeSet() != null) {
return getQueryMechanism().executeWriteWithChangeSet();
} else {
return getQueryMechanism().executeWrite();
}
}
/**
* INTERNAL:
* Decide whether to perform an insert, update or delete and
* delegate the work to the mechanism.
*/
public void executeCommit() throws DatabaseException, OptimisticLockException {
boolean doesExist = doesObjectExist();
boolean shouldBeDeleted = shouldObjectBeDeleted();
// Do insert, update or delete
if (doesExist) {
if (shouldBeDeleted) {
// Must do a delete
getQueryMechanism().deleteObjectForWrite();
} else {
// Must do an update
getQueryMechanism().updateObjectForWrite();
}
} else if (!shouldBeDeleted) {
// Must do an insert
getQueryMechanism().insertObjectForWrite();
}
}
/**
* INTERNAL:
* Perform a does exist check to decide whether to perform an insert or update and
* delegate the work to the mechanism.
*/
public void executeCommitWithChangeSet() throws DatabaseException, OptimisticLockException {
// Do insert of update
if (!getObjectChangeSet().isNew()) {
// Must do an update
if (!getSession().getCommitManager().isCommitInPreModify(objectChangeSet)) {
//If the changeSet is in the PreModify then it is in the process of being written
getQueryMechanism().updateObjectForWriteWithChangeSet();
}
} else {
// check whether the object is already being committed -
// if it is and it is new, then a shallow insert must be done
if (getSession().getCommitManager().isCommitInPreModify(objectChangeSet)) {
// a shallow insert must be performed
this.dontCascadeParts();
getQueryMechanism().insertObjectForWriteWithChangeSet();
getSession().getCommitManager().markShallowCommit(object);
} else {
// Must do an insert
getQueryMechanism().insertObjectForWriteWithChangeSet();
}
}
}
/**
* INTERNAL:
* Perform a shallow write. The decision, which shallow action should be
* executed is based on the existence of the associated object. If
* the object exists, perform a shallow delete. Do a shallow
* insert otherwise.
* Note that there currently is *no* shallow update operation.
* If shallow updates become necessary, the decision logic must
* also perform a delete check as in {@link this.executeCommit}.
*/
public void executeShallowWrite() {
boolean doesExist = doesObjectExist();
// Shallow writes only occur for inserts or deletes
if (doesExist) {
getQueryMechanism().shallowDeleteObjectForWrite(getObject(), this, getSession().getCommitManager());
} else {
getQueryMechanism().shallowInsertObjectForWrite(getObject(), this, getSession().getCommitManager());
}
}
/**
* PUBLIC:
* Return if this is a write object query.
*/
public boolean isWriteObjectQuery() {
return true;
}
/**
* INTERNAL:
* Prepare the receiver for execution in a session.
*/
public void prepareForExecution() throws QueryException {
super.prepareForExecution();
// Set the tranlation row, it may already be set in the custom query situation.
if ((getTranslationRow() == null) || (getTranslationRow().isEmpty())) {
setTranslationRow(getDescriptor().getObjectBuilder().buildRowForTranslation(getObject(), getSession()));
}
}
/**
* INTERNAL:
* Return whether a dependent object should be deleted from the database or not.
* Dependent objects should not be removed if not already scheduled for removal in a UoW.
* Returns "true" outside a UoW. Used by relationship mappings when cascading a delete operation.
*/
public boolean shouldDependentObjectBeDeleted(Object object) {
boolean shouldBeDeleted;
if (getSession().isUnitOfWork()) {
shouldBeDeleted = ((UnitOfWorkImpl)getSession()).isObjectDeleted(object);
} else {
// Deletes are cascaded outside a UoW
shouldBeDeleted = true;
}
return shouldBeDeleted;
}
/**
* INTERNAL:
* Return if the attached object should be deleted from the database or not.
* This information is available only, if the session is a UoW. Returns "false" outside a UoW.
* In this case an existence check should be performed and either an insert or update executed.
* Only used internally.
*/
protected boolean shouldObjectBeDeleted() {
boolean shouldBeDeleted;
if (getSession().isUnitOfWork()) {
shouldBeDeleted = ((UnitOfWorkImpl)getSession()).isObjectDeleted(getObject());
} else {
// Deletes must be explicitly user defined outside a UoW
shouldBeDeleted = false;
}
return shouldBeDeleted;
}
}
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