/** Return the expression from the attribute dervied from this expression. */
@Override
public Expression get(String attributeName, boolean forceInnerJoin) {
ObjectExpression result = derivedExpressionNamed(attributeName);
if (forceInnerJoin) {
result.doNotUseOuterJoin();
}
return result;
}
/** Defines a join between this expression and the target expression based on the ON clause. */
@Override
public Expression join(Expression target, Expression onClause) {
if (target instanceof ObjectExpression) {
((ObjectExpression) target).setJoinSource(this);
((ObjectExpression) target).setOnClause(onClause);
} else {
throw new IllegalArgumentException();
}
return this;
}
@Override
public Expression getAllowingNull(String attributeName) {
ObjectExpression exp = existingDerivedExpressionNamed(attributeName);
// The same (aliased) table cannot participate in a normal join and an outer join.
// To help enforce this, if the node already exists
if (exp != null) {
return exp;
}
ObjectExpression result = derivedExpressionNamed(attributeName);
result.doUseOuterJoin();
return result;
}
/**
* INTERNAL: This method is used when computing the nested queries for batch read mappings. It
* recurses computing the nested mapping queries.
*/
protected void computeNestedQueriesForBatchReadExpressions(Vector batchReadExpressions) {
for (int index = 0; index < batchReadExpressions.size(); index++) {
ObjectExpression objectExpression = (ObjectExpression) batchReadExpressions.get(index);
// Expression may not have been initialized.
ExpressionBuilder builder = objectExpression.getBuilder();
builder.setSession(getSession().getRootSession(null));
builder.setQueryClass(getReferenceClass());
// PERF: Cache join attribute names.
ObjectExpression baseExpression = objectExpression;
while (!baseExpression.getBaseExpression().isExpressionBuilder()) {
baseExpression = (ObjectExpression) baseExpression.getBaseExpression();
}
this.batchReadAttributes.add(baseExpression.getName());
// Ignore nested
if (objectExpression.getBaseExpression().isExpressionBuilder()) {
DatabaseMapping mapping = objectExpression.getMapping();
if ((mapping != null) && mapping.isForeignReferenceMapping()) {
// A nested query must be built to pass to the descriptor that looks like the real query
// execution would.
ReadQuery nestedQuery = ((ForeignReferenceMapping) mapping).prepareNestedBatchQuery(this);
// Register the nested query to be used by the mapping for all the objects.
getBatchReadMappingQueries().put(mapping, nestedQuery);
}
}
}
}
/**
* INTERNAL: Parses an expression to return the first non-AggregateObjectMapping expression after
* the base ExpressionBuilder. This is used by joining and batch fetch to get the list of mappings
* that really need to be processed (non-aggregates).
*
* @param aggregateMappingsEncountered - collection of aggregateObjectMapping expressions
* encountered in the returned expression between the first expression and the
* ExpressionBuilder
* @return first non-AggregateObjectMapping expression after the base ExpressionBuilder from the
* fullExpression
*/
public ObjectExpression getFirstNonAggregateExpressionAfterExpressionBuilder(
List aggregateMappingsEncountered) {
boolean done = false;
ObjectExpression baseExpression = this;
ObjectExpression prevExpression = this;
while (!baseExpression.getBaseExpression().isExpressionBuilder() && !done) {
baseExpression = (ObjectExpression) baseExpression.getBaseExpression();
while (!baseExpression.isExpressionBuilder()
&& baseExpression.getMapping().isAggregateObjectMapping()) {
aggregateMappingsEncountered.add(baseExpression.getMapping());
baseExpression = (ObjectExpression) baseExpression.getBaseExpression();
}
if (baseExpression.isExpressionBuilder()) {
done = true;
// use the one closest to the expression builder that wasn't an aggregate
baseExpression = prevExpression;
} else {
prevExpression = baseExpression;
}
}
return baseExpression;
}
/**
* INTERNAL: For CR#2456 if this is part of an objExp.equal(objExp), do not need to add additional
* expressions to normalizer both times, and the foreign key join replaces the equal expression.
*/
public Expression normalize(ExpressionNormalizer normalizer, Vector foreignKeyJoinPointer) {
if (hasBeenNormalized()) {
return this;
}
super.normalize(normalizer);
setHasBeenNormalized(true);
if ((getMapping() != null) && getMapping().isDirectToXMLTypeMapping()) {
normalizer.getStatement().setRequiresAliases(true);
}
// Check if any joins need to be added.
if (isAttribute()) {
return this;
}
// If the mapping is 'ref' or 'structure', no join needed.
if ((getMapping() != null)
&& (getMapping().isReferenceMapping() || getMapping().isStructureMapping())) {
normalizer.getStatement().setRequiresAliases(true);
return this;
}
// Compute if a distinct is required during normalization.
if (shouldQueryToManyRelationship()
&& (!normalizer.getStatement().isDistinctComputed())
&& (!normalizer.getStatement().isAggregateSelect())) {
normalizer.getStatement().useDistinct();
}
// Turn off DISTINCT if nestedTableMapping is used (not supported by Oracle 8.1.5).
if ((getMapping() != null) && getMapping().isNestedTableMapping()) {
// There are two types of nested tables, one used by clients, one used by mappings, do nothing
// in the mapping case.
if (!shouldQueryToManyRelationship()) {
return this;
}
normalizer.getStatement().dontUseDistinct();
}
Expression mappingExpression = mappingCriteria();
if (mappingExpression != null) {
mappingExpression = mappingExpression.normalize(normalizer);
}
if (mappingExpression != null) {
// If the join was an outer join we must not add the join criteria to the where clause,
// if the platform prints the join in the from clause.
if (shouldUseOuterJoin() && (getSession().getPlatform().isInformixOuterJoin())) {
normalizer.getStatement().getOuterJoinExpressions().addElement(this);
normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(mappingExpression);
normalizer.addAdditionalExpression(mappingExpression.and(additionalExpressionCriteria()));
return this;
} else if ((shouldUseOuterJoin() || isUsingOuterJoinForMultitableInheritance())
&& (!getSession().getPlatform().shouldPrintOuterJoinInWhereClause())) {
if (shouldUseOuterJoin()) {
normalizer.getStatement().getOuterJoinExpressions().addElement(this);
normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(mappingExpression);
normalizer
.getStatement()
.getOuterJoinedAdditionalJoinCriteria()
.addElement(additionalExpressionCriteriaMap());
normalizer.getStatement().getDescriptorsForMultitableInheritanceOnly().add(null);
return this;
} else {
if (isUsingOuterJoinForMultitableInheritance()) {
normalizer.getStatement().getOuterJoinExpressions().addElement(null);
normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(null);
normalizer
.getStatement()
.getOuterJoinedAdditionalJoinCriteria()
.addElement(additionalExpressionCriteriaMap());
normalizer
.getStatement()
.getDescriptorsForMultitableInheritanceOnly()
.add(getMapping().getReferenceDescriptor());
// fall through to the main case
}
}
}
// This must be added even if outer. Actually it should be converted to use a right outer
// join, but that gets complex
// so we do not support this current which is a limitation in some cases.
if (foreignKeyJoinPointer != null) {
// If this expression is right side of an objExp.equal(objExp), one
// need not add additionalExpressionCriteria twice.
// Also the join will replace the original objExp.equal(objExp).
// For CR#2456.
foreignKeyJoinPointer.add(mappingExpression);
} else {
normalizer.addAdditionalExpression(mappingExpression.and(additionalExpressionCriteria()));
}
}
// For bug 2900974 special code for DirectCollectionMappings moved to printSQL.
return this;
}
/** INTERNAL: Used for cloning. */
protected void postCopyIn(Map alreadyDone) {
super.postCopyIn(alreadyDone);
if (index != null) {
index = (IndexExpression) index.copiedVersionFrom(alreadyDone);
}
}
/** Defines a join between this expression and the target expression based on the ON clause. */
@Override
public Expression leftJoin(Expression target, Expression onClause) {
join(target, onClause);
((ObjectExpression) target).doUseOuterJoin();
return this;
}
