org.datanucleus.store.rdbms.query.ResultMetaDataROF Maven / Gradle / Ivy

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Plugin for DataNucleus providing persistence to RDBMS datastores.
There is a newer version: 6.0.8
/**********************************************************************
Copyright (c) 2007 Andy Jefferson and others. All rights reserved.
Licensed 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 "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Contributors:
    ...
**********************************************************************/
package org.datanucleus.store.rdbms.query;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
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.datanucleus.ExecutionContext;
import org.datanucleus.FetchPlan;
import org.datanucleus.exceptions.NucleusDataStoreException;
import org.datanucleus.exceptions.NucleusUserException;
import org.datanucleus.identity.IdentityUtils;
import org.datanucleus.metadata.AbstractClassMetaData;
import org.datanucleus.metadata.AbstractMemberMetaData;
import org.datanucleus.metadata.IdentityType;
import org.datanucleus.metadata.QueryResultMetaData;
import org.datanucleus.metadata.QueryResultMetaData.PersistentTypeMapping;
import org.datanucleus.state.ObjectProvider;
import org.datanucleus.store.FieldValues;
import org.datanucleus.store.fieldmanager.FieldManager;
import org.datanucleus.store.rdbms.mapping.StatementClassMapping;
import org.datanucleus.store.rdbms.mapping.StatementMappingIndex;
import org.datanucleus.store.rdbms.mapping.java.JavaTypeMapping;
import org.datanucleus.store.rdbms.table.Column;
import org.datanucleus.store.rdbms.table.DatastoreClass;
import org.datanucleus.store.rdbms.RDBMSStoreManager;
import org.datanucleus.util.Localiser;
import org.datanucleus.util.NucleusLogger;
import org.datanucleus.util.StringUtils;

/**
 * ResultObjectFactory that operates using a QueryResultMetaData and returns objects based on the definition.
 * A QueryResultMetaData allows for a row of a ResultSet to be returned as a mix of :-
 * 
 * a number of persistent objects (made up of several ResultSet columns)
 * a number of Objects (from individual ResultSet columns)
 * 
 * Each call to getObject() will then return a set of objects as per the MetaData definition.
 * ResultSet to object mapping
 * Each row of the ResultSet has a set of columns, and these columns are either used for direct outputting
 * back to the user as a "simple" object, or as a field in a persistent object. So you could have a situation
 * like this :-
 *  * ResultSet Column   Output Object
 * ================   =============
 * COL1               PC1.field1
 * COL2               PC1.field2
 * COL3               Simple Object
 * COL4               PC2.field3
 * COL5               PC2.field1
 * COL6               PC2.field2
 * COL7               Simple Object
 * COL8               PC1.field3
 * ...
 * 
 * So this example will return an Object[4] ... Object[0] = instance of PC1, Object[1] = instance of PC2,
 * Object[2] = simple object, Object[3] = simple object. 
 * When creating the instance of PC1 we take the ResultSet columns (COL1, COL2, COL8).
 * When creating the instance of PC2 we take the ResultSet columns (COL5, COL6, COL4).
 */
public class ResultMetaDataROF implements ResultObjectFactory
{
    /** Localisation of messages. */
    protected static final Localiser LOCALISER = Localiser.getInstance(
        "org.datanucleus.store.rdbms.Localisation", RDBMSStoreManager.class.getClassLoader());

    RDBMSStoreManager storeMgr;

    /** MetaData defining the result from the Query. */
    QueryResultMetaData queryResultMetaData = null;

    String[] columnNames = null;

    private boolean ignoreCache = false;

    /**
     * Constructor.
     * @param storeMgr RDBMS StoreManager
     * @param qrmd MetaData defining the results from the query.
     */
    public ResultMetaDataROF(RDBMSStoreManager storeMgr, QueryResultMetaData qrmd)
    {
        this.storeMgr = storeMgr;
        this.queryResultMetaData = qrmd;
    }

    /**
     * Accessor for the object(s) from a row of the ResultSet.
     * @param ec execution context
     * @param rs ResultSet
     * @return The object(s) for this row of the ResultSet.
     */
    public Object getObject(ExecutionContext ec, ResultSet rs)
    {
        List returnObjects = new ArrayList();
        if (columnNames == null)
        {
            try
            {
                //obtain column names
                ResultSetMetaData rsmd = rs.getMetaData();
                int columnCount = rsmd.getColumnCount();
                columnNames = new String[columnCount];
                for( int i=0; i