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package org.apache.cayenne.access.util;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.DataObject;
import org.apache.cayenne.ObjectId;
import org.apache.cayenne.access.QueryEngine;
import org.apache.cayenne.exp.Expression;
import org.apache.cayenne.exp.ExpressionFactory;
import org.apache.cayenne.map.DbRelationship;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.query.SelectQuery;
/**
* Implements helper methods that perform different query-related operations.
*
* @author Andrus Adamchik
* @deprecated In 1.2 Cayenne supports specialized queries such as
* {@link org.apache.cayenne.query.ObjectIdQuery} and
* {@link org.apache.cayenne.query.RelationshipQuery}, making this class
* redundant.
*/
public class QueryUtils {
/**
* Creates and returns a select query that can be used to fetch an object given an
* ObjectId.
*/
public static SelectQuery selectObjectForId(ObjectId oid) {
return new SelectQuery(oid.getEntityName(), ExpressionFactory.matchAllDbExp(oid
.getIdSnapshot(), Expression.EQUAL_TO));
}
/**
* Creates and returns a select query that can be used to fetch a list of objects
* given a list of ObjectIds. All ObjectIds must belong to the same entity.
*/
public static SelectQuery selectQueryForIds(List oids) {
if (oids == null || oids.size() == 0) {
throw new IllegalArgumentException("List must contain at least one ObjectId");
}
SelectQuery sel = new SelectQuery();
sel.setRoot(((ObjectId) oids.get(0)).getEntityName());
Iterator it = oids.iterator();
ObjectId firstId = (ObjectId) it.next();
Expression exp = ExpressionFactory.matchAllDbExp(
firstId.getIdSnapshot(),
Expression.EQUAL_TO);
while (it.hasNext()) {
ObjectId anId = (ObjectId) it.next();
exp = exp.orExp(ExpressionFactory.matchAllDbExp(
anId.getIdSnapshot(),
Expression.EQUAL_TO));
}
sel.setQualifier(exp);
return sel;
}
/**
* Generates a SelectQuery that can be used to fetch relationship destination objects
* given a source object of a to-many relationship.
*/
public static SelectQuery selectRelationshipObjects(
QueryEngine e,
DataObject source,
String relName) {
ObjEntity ent = e.getEntityResolver().lookupObjEntity(source);
ObjRelationship rel = (ObjRelationship) ent.getRelationship(relName);
ObjEntity destEnt = (ObjEntity) rel.getTargetEntity();
List dbRels = rel.getDbRelationships();
// sanity check
if (dbRels == null || dbRels.size() == 0) {
throw new CayenneRuntimeException("ObjRelationship '"
+ rel.getName()
+ "' is unmapped.");
}
// build a reverse DB path
// ...while reverse ObjRelationship may be absent,
// reverse DB must always be there...
StringBuffer buf = new StringBuffer();
ListIterator it = dbRels.listIterator(dbRels.size());
while (it.hasPrevious()) {
if (buf.length() > 0) {
buf.append(".");
}
DbRelationship dbRel = (DbRelationship) it.previous();
DbRelationship reverse = dbRel.getReverseRelationship();
// another sanity check
if (reverse == null) {
throw new CayenneRuntimeException("DbRelationship '"
+ dbRel.getName()
+ "' has no reverse relationship");
}
buf.append(reverse.getName());
}
SelectQuery select = new SelectQuery(destEnt);
select.setQualifier(ExpressionFactory.matchDbExp(buf.toString(), source));
// resolve inheritance
select.setResolvingInherited(true);
return select;
}
}