package org.apache.ojb.broker.query;

import org.apache.ojb.broker.Identity;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache ObjectRelationalBridge" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache ObjectRelationalBridge", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


/**
 * represents a search by identity.
 * "find the article with id 7"
 * could be represented as:
 *
 * Article example = new Article();
 * example.setId(7);
 * Query qry = new QueryByIdentity(example);
 *
 * The PersistenceBroker can retrieve Objects by examples as follows:
 *
 * PersistenceBroker broker = PersistenceBrokerFactory.createPersistenceBroker();
 * Collection col = broker.getObjectByQuery(qry);
 *
 * This Class can also handle working with OJB Identity objects:
 * "find the article with Identity xyz" could be represnted as
 * Identity xyz = new Identity(example);
 * Query qry = new QueryByIdentity(xyz);
 *
 * @author <a href="mailto:thma@apache.org">Thomas Mahler<a>
 * @version $Id: QueryByIdentity.java,v 1.1 2002/09/20 17:17:16 brj Exp $
 */
public class QueryByIdentity extends AbstractQueryImpl implements Query
{
    private Object exampleObject;

    /**
     * QueryByIdentity can be generated from example Objects or by Identity Objects
     */
    public QueryByIdentity(Object example_or_identity)
    {
        exampleObject = example_or_identity;
    }

    /**
     * no Criteria available
     * @return null
     */
    public Criteria getCriteria()
    {
        return null;
    }

    /**
     * Answer the example Object
     * @return Object
     */
    public java.lang.Object getExampleObject()
    {
        return exampleObject;
    }

    /**
     * Answer the search class. 
     * This is the class of the example object or the class represented by 
     * the Identity.
     * @return Class
     */
    public java.lang.Class getSearchClass()
    {
    	Object obj = getExampleObject();
    	
    	if (obj instanceof Identity)
    	{
    		return ((Identity)obj).getObjectsClass();
    	}
    	else
    	{	
        	return obj.getClass();
    	}
    }

    /*
	 * @see Query#isDistinct()
	 */
    public boolean isDistinct()
    {
        return false;
    }

}