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Cayenne Object Persistence Framework
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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****************************************************************/
package org.apache.cayenne.access.trans;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.access.jdbc.ColumnDescriptor;
import org.apache.cayenne.exp.Expression;
import org.apache.cayenne.map.DbAttribute;
import org.apache.cayenne.map.DbEntity;
import org.apache.cayenne.map.DbJoin;
import org.apache.cayenne.map.DbRelationship;
import org.apache.cayenne.map.DerivedDbEntity;
import org.apache.cayenne.map.EntityInheritanceTree;
import org.apache.cayenne.map.ObjAttribute;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.query.PrefetchSelectQuery;
import org.apache.cayenne.query.PrefetchTreeNode;
import org.apache.cayenne.query.SelectQuery;
/**
* A builder of JDBC PreparedStatements based on Cayenne SelectQueries. Translates
* SelectQuery to parameterized SQL string and wraps it in a PreparedStatement.
* SelectTranslator is stateful and thread-unsafe.
*
* @author Andrei Adamchik
*/
public class SelectTranslator extends QueryAssembler {
protected static final int[] UNSUPPORTED_DISTINCT_TYPES = new int[] {
Types.BLOB, Types.CLOB, Types.LONGVARBINARY, Types.LONGVARCHAR
};
protected static boolean isUnsupportedForDistinct(int type) {
for (int i = 0; i < UNSUPPORTED_DISTINCT_TYPES.length; i++) {
if (UNSUPPORTED_DISTINCT_TYPES[i] == type) {
return true;
}
}
return false;
}
final Map aliasLookup = new HashMap();
final List tableList = new ArrayList();
final List aliasList = new ArrayList();
final List dbRelList = new ArrayList();
List resultColumns;
List groupByList;
Map attributeOverrides;
Map defaultAttributesByColumn;
int aliasCounter;
boolean suppressingDistinct;
/**
* If set to true, indicates that distinct select query is required no
* matter what the original query settings where. This flag can be set when joins are
* created using "to-many" relationships.
*/
boolean forcingDistinct;
/**
* Returns a list of DbAttributes representing columns in this query.
*
* @deprecated since 1.2 - contents of this list are now ColumnDescriptors, not
* DbAttributes. Anyway, use getResultColumns() instead to reduce
* confusion.
*/
protected List getColumns() {
return resultColumns;
}
/**
* Returns query translated to SQL. This is a main work method of the
* SelectTranslator.
*/
public String createSqlString() throws Exception {
forcingDistinct = false;
// build column list
this.resultColumns = buildResultColumns();
QualifierTranslator tr = adapter.getQualifierTranslator(this);
// build parent qualifier
// Parent qualifier translation must PRECEED main qualifier
// since it will be appended first and its parameters must
// go first as well
String parentQualifierStr = null;
if (getSelectQuery().isQualifiedOnParent()) {
tr.setTranslateParentQual(true);
parentQualifierStr = tr.doTranslation();
}
// build main qualifier
tr.setTranslateParentQual(false);
String qualifierStr = tr.doTranslation();
// build GROUP BY
this.groupByList = buildGroupByList();
// build ORDER BY
OrderingTranslator orderingTranslator = new OrderingTranslator(this);
String orderByStr = orderingTranslator.doTranslation();
// assemble
StringBuffer queryBuf = new StringBuffer();
queryBuf.append("SELECT ");
// check if DISTINCT is appropriate
// side effect: "suppressingDistinct" flag may end up being flipped here
if (forcingDistinct || getSelectQuery().isDistinct()) {
suppressingDistinct = false;
Iterator it = resultColumns.iterator();
while (it.hasNext()) {
ColumnDescriptor column = (ColumnDescriptor) it.next();
if (isUnsupportedForDistinct(column.getJdbcType())) {
suppressingDistinct = true;
break;
}
}
if (!suppressingDistinct) {
queryBuf.append("DISTINCT ");
}
}
// convert ColumnDescriptors to column names
List selectColumnExpList = new ArrayList();
Iterator it = resultColumns.iterator();
while (it.hasNext()) {
ColumnDescriptor column = (ColumnDescriptor) it.next();
selectColumnExpList.add(column.getQualifiedColumnName());
}
// append any column expressions used in the order by if this query
// uses the DISTINCT modifier
if (forcingDistinct || getSelectQuery().isDistinct()) {
List orderByColumnList = orderingTranslator.getOrderByColumnList();
for (int i = 0; i < orderByColumnList.size(); i++) {
// Convert to ColumnDescriptors??
Object orderByColumnExp = orderByColumnList.get(i);
if (!selectColumnExpList.contains(orderByColumnExp)) {
selectColumnExpList.add(orderByColumnExp);
}
}
}
// append columns (unroll the loop's first element)
int columnCount = selectColumnExpList.size();
queryBuf.append((String) selectColumnExpList.get(0));
// assume there is at least 1 element
for (int i = 1; i < columnCount; i++) {
queryBuf.append(", ");
queryBuf.append((String) selectColumnExpList.get(i));
}
// append from clause
queryBuf.append(" FROM ");
// append table list (unroll loop's 1st element)
int tableCount = tableList.size();
appendTable(queryBuf, 0); // assume there is at least 1 table
for (int i = 1; i < tableCount; i++) {
queryBuf.append(", ");
appendTable(queryBuf, i);
}
// append db relationship joins if any
boolean hasWhere = false;
int dbRelCount = dbRelList.size();
if (dbRelCount > 0) {
hasWhere = true;
queryBuf.append(" WHERE ");
appendJoins(queryBuf, 0);
for (int i = 1; i < dbRelCount; i++) {
queryBuf.append(" AND ");
appendJoins(queryBuf, i);
}
}
// append parent qualifier if any
if (parentQualifierStr != null) {
if (hasWhere) {
queryBuf.append(" AND (");
queryBuf.append(parentQualifierStr);
queryBuf.append(")");
}
else {
hasWhere = true;
queryBuf.append(" WHERE ");
queryBuf.append(parentQualifierStr);
}
}
// append group by
boolean hasGroupBy = false;
if (groupByList != null) {
int groupByCount = groupByList.size();
if (groupByCount > 0) {
hasGroupBy = true;
queryBuf.append(" GROUP BY ");
appendGroupBy(queryBuf, 0);
for (int i = 1; i < groupByCount; i++) {
queryBuf.append(", ");
appendGroupBy(queryBuf, i);
}
}
}
// append qualifier
if (qualifierStr != null) {
if (hasGroupBy) {
queryBuf.append(" HAVING ");
queryBuf.append(qualifierStr);
}
else {
if (hasWhere) {
queryBuf.append(" AND (");
queryBuf.append(qualifierStr);
queryBuf.append(")");
}
else {
hasWhere = true;
queryBuf.append(" WHERE ");
queryBuf.append(qualifierStr);
}
}
}
// append prebuilt ordering
if (orderByStr != null) {
queryBuf.append(" ORDER BY ").append(orderByStr);
}
return queryBuf.toString();
}
/**
* Returns a list of ColumnDescriptors for the query columns.
*
* @since 1.2
*/
public ColumnDescriptor[] getResultColumns() {
if (resultColumns == null || resultColumns.isEmpty()) {
return new ColumnDescriptor[0];
}
return (ColumnDescriptor[]) resultColumns
.toArray(new ColumnDescriptor[resultColumns.size()]);
}
/**
* Returns a map of ColumnDescriptors keyed by ObjAttribute for columns that may need
* to be reprocessed manually due to incompatible mappings along the inheritance
* hierarchy.
*
* @since 1.2
*/
public Map getAttributeOverrides() {
return attributeOverrides != null ? attributeOverrides : Collections.EMPTY_MAP;
}
/**
* Returns true if SelectTranslator determined that a query requiring DISTINCT can't
* be run with DISTINCT keyword for internal reasons. If this method returns true,
* DataNode may need to do in-memory distinct filtering.
*
* @since 1.1
*/
public boolean isSuppressingDistinct() {
return suppressingDistinct;
}
private SelectQuery getSelectQuery() {
return (SelectQuery) getQuery();
}
/**
* Creates a list of columns used in the query's GROUP BY clause.
*/
private List buildGroupByList() {
DbEntity dbEntity = getRootDbEntity();
return (dbEntity instanceof DerivedDbEntity) ? ((DerivedDbEntity) dbEntity)
.getGroupByAttributes() : Collections.EMPTY_LIST;
}
List buildResultColumns() {
this.defaultAttributesByColumn = new HashMap();
// create alias for root table
newAliasForTable(getRootDbEntity());
List columns = new ArrayList();
SelectQuery query = getSelectQuery();
// for query with custom attributes use a different strategy
if (query.isFetchingCustomAttributes()) {
appendCustomColumns(columns, query);
}
else {
appendQueryColumns(columns, query);
}
return columns;
}
/**
* Appends columns needed for object SelectQuery to the provided columns list.
*/
// TODO: this whole method screams REFACTORING!!!
List appendQueryColumns(List columns, SelectQuery query) {
Set attributes = new HashSet();
// fetched attributes include attributes that are either:
//
// * class properties
// * PK
// * FK used in relationships
// * GROUP BY
// * joined prefetch PK
ObjEntity oe = getRootEntity();
// null tree will indicate that we don't take inheritance into account
EntityInheritanceTree tree = null;
if (query.isResolvingInherited()) {
tree = getRootInheritanceTree();
}
// ObjEntity attrs
Iterator attrs = (tree != null) ? tree.allAttributes().iterator() : oe
.getAttributes()
.iterator();
while (attrs.hasNext()) {
ObjAttribute oa = (ObjAttribute) attrs.next();
Iterator dbPathIterator = oa.getDbPathIterator();
while (dbPathIterator.hasNext()) {
Object pathPart = dbPathIterator.next();
if (pathPart instanceof DbRelationship) {
DbRelationship rel = (DbRelationship) pathPart;
dbRelationshipAdded(rel);
}
else if (pathPart instanceof DbAttribute) {
DbAttribute dbAttr = (DbAttribute) pathPart;
if (dbAttr == null) {
throw new CayenneRuntimeException(
"ObjAttribute has no DbAttribute: " + oa.getName());
}
appendColumn(columns, oa, dbAttr, attributes, null);
}
}
}
// relationship keys
Iterator rels = (tree != null) ? tree.allRelationships().iterator() : oe
.getRelationships()
.iterator();
while (rels.hasNext()) {
ObjRelationship rel = (ObjRelationship) rels.next();
DbRelationship dbRel = (DbRelationship) rel.getDbRelationships().get(0);
List joins = dbRel.getJoins();
int len = joins.size();
for (int i = 0; i < len; i++) {
DbJoin join = (DbJoin) joins.get(i);
DbAttribute src = join.getSource();
appendColumn(columns, null, src, attributes, null);
}
}
// add remaining needed attrs from DbEntity
DbEntity table = getRootDbEntity();
Iterator pk = table.getPrimaryKey().iterator();
while (pk.hasNext()) {
DbAttribute dba = (DbAttribute) pk.next();
appendColumn(columns, null, dba, attributes, null);
}
// special handling of a disjoint query...
// TODO, Andrus 11/17/2005 - resultPath mechansim is generic and should probably
// be moved in the superclass (SelectQuery), replacing customDbAttributes.
if (query instanceof PrefetchSelectQuery) {
Iterator extraPaths = ((PrefetchSelectQuery) query)
.getResultPaths()
.iterator();
// for each relationship path add closest FK or PK, for each attribute path,
// add specified column
while (extraPaths.hasNext()) {
String path = (String) extraPaths.next();
Expression pathExp = oe.translateToDbPath(Expression.fromString(path));
Iterator it = table.resolvePathComponents(pathExp);
// add joins and find terminating element
Object pathComponent = null;
while (it.hasNext()) {
pathComponent = it.next();
// do not add join for the last DB Rel
if (it.hasNext() && pathComponent instanceof DbRelationship) {
dbRelationshipAdded((DbRelationship) pathComponent);
}
}
String labelPrefix = pathExp.toString().substring("db:".length());
// process terminating element
if (pathComponent instanceof DbAttribute) {
// label prefix already includes relationship name
appendColumn(
columns,
null,
(DbAttribute) pathComponent,
attributes,
labelPrefix);
}
else if (pathComponent instanceof DbRelationship) {
DbRelationship relationship = (DbRelationship) pathComponent;
// add last join
if (relationship.isToMany()) {
dbRelationshipAdded(relationship);
}
Iterator joins = relationship.getJoins().iterator();
while (joins.hasNext()) {
DbJoin j = (DbJoin) joins.next();
DbAttribute attribute = relationship.isToMany()
? j.getTarget()
: j.getSource();
// note that we my select a source attribute, but label it as
// target for simplified snapshot processing
appendColumn(columns, null, attribute, attributes, labelPrefix
+ '.'
+ j.getTargetName());
}
}
}
}
// handle joint prefetches directly attached to this query...
if (query.getPrefetchTree() != null) {
Iterator jointPrefetches = query
.getPrefetchTree()
.adjacentJointNodes()
.iterator();
while (jointPrefetches.hasNext()) {
PrefetchTreeNode prefetch = (PrefetchTreeNode) jointPrefetches.next();
// for each prefetch add all joins plus columns from the target entity
Expression prefetchExp = Expression.fromString(prefetch.getPath());
Expression dbPrefetch = oe.translateToDbPath(prefetchExp);
Iterator it = table.resolvePathComponents(dbPrefetch);
DbRelationship r = null;
while (it.hasNext()) {
r = (DbRelationship) it.next();
dbRelationshipAdded(r);
}
if (r == null) {
throw new CayenneRuntimeException("Invalid joint prefetch '"
+ prefetch
+ "' for entity: "
+ oe.getName());
}
// add columns from the target entity, skipping those that are an FK to
// source entity
Collection skipColumns = Collections.EMPTY_LIST;
if (r.getSourceEntity() == table) {
skipColumns = new ArrayList(2);
Iterator joins = r.getJoins().iterator();
while (joins.hasNext()) {
DbJoin join = (DbJoin) joins.next();
if (attributes.contains(join.getSource())) {
skipColumns.add(join.getTarget());
}
}
}
// go via target OE to make sure that Java types are mapped correctly...
ObjRelationship targetRel = (ObjRelationship) prefetchExp.evaluate(oe);
Iterator targetObjAttrs = targetRel
.getTargetEntity()
.getAttributes()
.iterator();
String labelPrefix = dbPrefetch.toString().substring("db:".length());
while (targetObjAttrs.hasNext()) {
ObjAttribute oa = (ObjAttribute) targetObjAttrs.next();
Iterator dbPathIterator = oa.getDbPathIterator();
while (dbPathIterator.hasNext()) {
Object pathPart = dbPathIterator.next();
if (pathPart instanceof DbRelationship) {
DbRelationship rel = (DbRelationship) pathPart;
dbRelationshipAdded(rel);
}
else if (pathPart instanceof DbAttribute) {
DbAttribute attribute = (DbAttribute) pathPart;
if (attribute == null) {
throw new CayenneRuntimeException(
"ObjAttribute has no DbAttribute: "
+ oa.getName());
}
if (!skipColumns.contains(attribute)) {
appendColumn(
columns,
oa,
attribute,
attributes,
labelPrefix + '.' + attribute.getName());
}
}
}
}
// append remaining target attributes such as keys
Iterator targetAttributes = r
.getTargetEntity()
.getAttributes()
.iterator();
while (targetAttributes.hasNext()) {
DbAttribute attribute = (DbAttribute) targetAttributes.next();
if (!skipColumns.contains(attribute)) {
appendColumn(columns, null, attribute, attributes, labelPrefix
+ '.'
+ attribute.getName());
}
}
}
}
return columns;
}
/**
* Appends custom columns from SelectQuery to the provided list.
*/
List appendCustomColumns(List columns, SelectQuery query) {
List customAttributes = query.getCustomDbAttributes();
DbEntity table = getRootDbEntity();
int len = customAttributes.size();
for (int i = 0; i < len; i++) {
DbAttribute attribute = (DbAttribute) table
.getAttribute((String) customAttributes.get(i));
if (attribute == null) {
throw new CayenneRuntimeException("Attribute does not exist: "
+ customAttributes.get(i));
}
String alias = aliasForTable((DbEntity) attribute.getEntity());
columns.add(new ColumnDescriptor(attribute, alias));
}
return columns;
}
private void appendColumn(
List columns,
ObjAttribute objAttribute,
DbAttribute attribute,
Set skipSet,
String label) {
if (skipSet.add(attribute)) {
String alias = aliasForTable((DbEntity) attribute.getEntity());
ColumnDescriptor column = (objAttribute != null) ? new ColumnDescriptor(
objAttribute,
attribute,
alias) : new ColumnDescriptor(attribute, alias);
if (label != null) {
column.setLabel(label);
}
columns.add(column);
// TODO: andrus, 5/7/2006 - replace 'columns' collection with this map, as it
// is redundant
defaultAttributesByColumn.put(column, objAttribute);
}
else if (objAttribute != null) {
// record ObjAttribute override
for (int i = 0; i < columns.size(); i++) {
ColumnDescriptor column = (ColumnDescriptor) columns.get(i);
if (attribute.getName().equals(column.getName())) {
if (attributeOverrides == null) {
attributeOverrides = new HashMap();
}
attributeOverrides.put(objAttribute, column);
// kick out the original attribute
ObjAttribute original = (ObjAttribute) defaultAttributesByColumn
.remove(column);
if (original != null) {
attributeOverrides.put(original, column);
column.setJavaClass(Void.TYPE.getName());
}
break;
}
}
}
}
private void appendGroupBy(StringBuffer queryBuf, int index) {
DbAttribute column = (DbAttribute) groupByList.get(index);
String alias = aliasForTable((DbEntity) column.getEntity());
queryBuf.append(column.getAliasedName(alias));
}
private void appendTable(StringBuffer queryBuf, int index) {
DbEntity ent = (DbEntity) tableList.get(index);
queryBuf.append(ent.getFullyQualifiedName());
// The alias should be the alias from the same index in aliasList, not that
// returned by aliasForTable.
queryBuf.append(' ').append((String) aliasList.get(index));
}
private void appendJoins(StringBuffer queryBuf, int index) {
DbRelationship rel = (DbRelationship) dbRelList.get(index);
String srcAlias = aliasForTable((DbEntity) rel.getSourceEntity());
String targetAlias = (String) aliasLookup.get(rel);
boolean andFlag = false;
List joins = rel.getJoins();
int len = joins.size();
for (int i = 0; i < len; i++) {
DbJoin join = (DbJoin) joins.get(i);
if (andFlag) {
queryBuf.append(" AND ");
}
else {
andFlag = true;
}
queryBuf.append(srcAlias).append('.').append(join.getSourceName()).append(
" = ").append(targetAlias).append('.').append(join.getTargetName());
}
}
/**
* Stores a new relationship in an internal list. Later it will be used to create
* joins to relationship destination table.
*/
public void dbRelationshipAdded(DbRelationship rel) {
if (rel.isToMany()) {
forcingDistinct = true;
}
String existAlias = (String) aliasLookup.get(rel);
if (existAlias == null) {
dbRelList.add(rel);
// add alias for the destination table of the relationship
String newAlias = newAliasForTable((DbEntity) rel.getTargetEntity());
aliasLookup.put(rel, newAlias);
}
}
/**
* Sets up and returns a new alias for a speciafied table.
*/
protected String newAliasForTable(DbEntity ent) {
if (ent instanceof DerivedDbEntity) {
ent = ((DerivedDbEntity) ent).getParentEntity();
}
String newAlias = "t" + aliasCounter++;
tableList.add(ent);
aliasList.add(newAlias);
return newAlias;
}
public String aliasForTable(DbEntity ent, DbRelationship rel) {
return (String) aliasLookup.get(rel);
}
/**
* Overrides superclass implementation. Will return an alias that should be used for a
* specified DbEntity in the query (or null if this DbEntity is not included in the
* FROM clause).
*/
public String aliasForTable(DbEntity ent) {
if (ent instanceof DerivedDbEntity) {
ent = ((DerivedDbEntity) ent).getParentEntity();
}
int entIndex = tableList.indexOf(ent);
if (entIndex >= 0) {
return (String) aliasList.get(entIndex);
}
else {
StringBuffer msg = new StringBuffer();
msg.append("Alias not found, DbEntity: '").append(
ent != null ? ent.getName() : "").append(
"'\nExisting aliases:");
int len = aliasList.size();
for (int i = 0; i < len; i++) {
String dbeName = (tableList.get(i) != null) ? ((DbEntity) tableList
.get(i)).getName() : "";
msg.append("\n").append(aliasList.get(i)).append(" => ").append(dbeName);
}
throw new CayenneRuntimeException(msg.toString());
}
}
/**
* Always returns true.
*/
public boolean supportsTableAliases() {
return true;
}
}
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