bundles/org.simantics.db.common/src/org/simantics/db/common/request/SingleObjectWithType.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.common.request;
  13
  14 import org.simantics.db.ReadGraph;
  15 import org.simantics.db.Resource;
  16 import org.simantics.db.common.utils.NameUtils;
  17 import org.simantics.db.exception.DatabaseException;
  18 import org.simantics.db.exception.NoSingleResultException;
  19
  20 /**
  21  * @author Tuukka Lehtonen
  22  */
  23 public final class SingleObjectWithType extends ResourceRead3<Resource> {
  24
  25     public SingleObjectWithType(Resource resource, Resource predicate, Resource type) {
  26         super(resource, predicate, type);
  27     }
  28
  29     @Override
  30     public Resource perform(ReadGraph graph) throws DatabaseException {
  31         Resource result = null;
  32         for (Resource object : graph.getObjects(resource, resource2)) {
  33             if (graph.isInstanceOf(object, resource3)) {
  34                 if (result != null)
  35                     throw new NoSingleResultException("More than 1 objects for relation "
  36                             + NameUtils.getSafeName(graph, resource2) + " with type "
  37                             + NameUtils.getSafeName(graph, resource3) + " at "
  38                             + NameUtils.getSafeName(graph, resource));
  39
  40                 result = object;
  41             }
  42         }
  43
  44         if (result == null)
  45             throw new NoSingleResultException("No objects for relation "
  46                     + NameUtils.getSafeName(graph, resource2) + " with type "
  47                     + NameUtils.getSafeName(graph, resource3) + " at "
  48                     + NameUtils.getSafeName(graph, resource));
  49
  50         return result;
  51     }
  52
  53 }