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package org.apache.cayenne.util;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.cayenne.ObjectContext;
import org.apache.cayenne.ObjectId;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.QueryResponse;
import org.apache.cayenne.property.ArcProperty;
import org.apache.cayenne.property.ClassDescriptor;
import org.apache.cayenne.query.ObjectIdQuery;
import org.apache.cayenne.query.Query;
import org.apache.cayenne.query.QueryMetadata;
import org.apache.cayenne.query.RelationshipQuery;

/**
 * A helper class that implements
 * {@link org.apache.cayenne.DataChannel#onQuery(ObjectContext, Query)} logic on
 * behalf of an ObjectContext.
 * 

* Intended for internal use only. *

* * @since 1.2 * @author Andrus Adamchik */ public class ObjectContextQueryAction { protected static final boolean DONE = true; protected ObjectContext targetContext; protected ObjectContext actingContext; protected Query query; protected QueryMetadata metadata; protected transient QueryResponse response; public ObjectContextQueryAction(ObjectContext actingContext, ObjectContext targetContext, Query query) { this.actingContext = actingContext; this.query = query; // no special target context and same target context as acting context mean the // same thing. "normalize" the internal state to avoid confusion this.targetContext = targetContext != actingContext ? targetContext : null; this.metadata = query.getMetaData(actingContext.getEntityResolver()); } /** * Worker method that perfomrs internal query. */ public QueryResponse execute() { if (interceptOIDQuery() != DONE) { if (interceptRelationshipQuery() != DONE) { runQuery(); } } interceptObjectConversion(); return response; } /** * Transfers fetched objects into the target context if it is different from "acting" * context. Note that when this method is invoked, result objects are already * registered with acting context by the parent channel. */ protected void interceptObjectConversion() { if (targetContext != null && !metadata.isFetchingDataRows()) { // rewrite response to contain objects from the query context GenericResponse childResponse = new GenericResponse(); for (response.reset(); response.next();) { if (response.isList()) { List objects = response.currentList(); if (objects.isEmpty()) { childResponse.addResultList(objects); } else { // TODO: Andrus 1/31/2006 - IncrementalFaultList is not properly // transferred between contexts.... List childObjects = new ArrayList(objects.size()); Iterator it = objects.iterator(); while (it.hasNext()) { Persistent object = (Persistent) it.next(); childObjects.add(targetContext.localObject(object .getObjectId(), object)); } childResponse.addResultList(childObjects); } } else { childResponse.addBatchUpdateCount(response.currentUpdateCount()); } } response = childResponse; } } protected boolean interceptOIDQuery() { if (query instanceof ObjectIdQuery) { ObjectIdQuery oidQuery = (ObjectIdQuery) query; if (!oidQuery.isFetchMandatory() && !oidQuery.isFetchingDataRows()) { Object object = actingContext.getGraphManager().getNode( oidQuery.getObjectId()); if (object != null) { this.response = new ListResponse(object); return DONE; } } } return !DONE; } protected boolean interceptRelationshipQuery() { if (query instanceof RelationshipQuery) { RelationshipQuery relationshipQuery = (RelationshipQuery) query; if (!relationshipQuery.isRefreshing()) { // don't intercept to-many relationships if fetch is done to the same // context as the root context of this action - this will result in an // infinite loop. if (targetContext == null && relationshipQuery.getRelationship( actingContext.getEntityResolver()).isToMany()) { return !DONE; } ObjectId id = relationshipQuery.getObjectId(); Object object = actingContext.getGraphManager().getNode(id); if (object != null) { ClassDescriptor descriptor = actingContext .getEntityResolver() .getClassDescriptor(id.getEntityName()); if (!descriptor.isFault(object)) { ArcProperty property = (ArcProperty) descriptor .getProperty(relationshipQuery.getRelationshipName()); if (!property.isFault(object)) { Object related = property.readPropertyDirectly(object); List result; // null to-one if (related == null) { result = new ArrayList(1); } // to-many else if (related instanceof List) { result = (List) related; } // non-null to-one else { result = new ArrayList(1); result.add(related); } this.response = new ListResponse(result); return DONE; } } } } } return !DONE; } /** * Fetches data from the channel. */ protected void runQuery() { this.response = actingContext.getChannel().onQuery(actingContext, query); } }




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