/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */


package org.apache.commons.beanutils;


import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


Implementation of DynaClass that creates an in-memory collection of DynaBeans representing the results of an SQL query. Once the DynaClass instance has been created, the JDBC ResultSet
and Statement on which it is based can be closed, and the
underlying Connection can be returned to its connection pool
(if you are using one).
The normal usage pattern is something like:
  Connection conn = ...;  // Acquire connection from pool
  Statement stmt = conn.createStatement();
  ResultSet rs = stmt.executeQuery("SELECT ...");
  RowSetDynaClass rsdc = new RowSetDynaClass(rs);
  rs.close();
  stmt.close();
  ...;                    // Return connection to pool
  List rows = rsdc.getRows();
  ...;                   // Process the rows as desired

Each column in the result set will be represented as a DynaBean property of the corresponding name (optionally forced to lower case for portability). There will be one DynaBean in the List returned by getRows() for each
row in the original ResultSet.
In general, instances of RowSetDynaClass can be serialized and deserialized, which will automatically include the list of DynaBeans representing the data content. The only exception to this rule would be when the underlying property values that were copied from the ResultSet originally cannot themselves be serialized. Therefore, a RowSetDynaClass makes a very convenient mechanism for transporting data sets to remote Java-based application components.
Version:
$Id$/**
 * <p>Implementation of {@link DynaClass} that creates an in-memory collection
 * of {@link DynaBean}s representing the results of an SQL query.  Once the
 * {@link DynaClass} instance has been created, the JDBC <code>ResultSet</code>
 * and <code>Statement</code> on which it is based can be closed, and the
 * underlying <code>Connection</code> can be returned to its connection pool
 * (if you are using one).</p>
 *
 * <p>The normal usage pattern is something like:</p>
 * <pre>
 *   Connection conn = ...;  // Acquire connection from pool
 *   Statement stmt = conn.createStatement();
 *   ResultSet rs = stmt.executeQuery("SELECT ...");
 *   RowSetDynaClass rsdc = new RowSetDynaClass(rs);
 *   rs.close();
 *   stmt.close();
 *   ...;                    // Return connection to pool
 *   List rows = rsdc.getRows();
 *   ...;                   // Process the rows as desired
 * </pre>
 *
 * <p>Each column in the result set will be represented as a {@link DynaBean}
 * property of the corresponding name (optionally forced to lower case
 * for portability).  There will be one {@link DynaBean} in the
 * <code>List</code> returned by <code>getRows()</code> for each
 * row in the original <code>ResultSet</code>.</p>
 *
 * <p>In general, instances of {@link RowSetDynaClass} can be serialized
 * and deserialized, which will automatically include the list of
 * {@link DynaBean}s representing the data content.  The only exception
 * to this rule would be when the underlying property values that were
 * copied from the <code>ResultSet</code> originally cannot themselves
 * be serialized.  Therefore, a {@link RowSetDynaClass} makes a very
 * convenient mechanism for transporting data sets to remote Java-based
 * application components.</p>
 *
 * @version $Id$
 */

public class RowSetDynaClass extends JDBCDynaClass implements DynaClass, Serializable {


    // ----------------------------------------------------- Instance variables

    
Limits the size of the returned list.  The call to
getRows() will return at most limit number of rows.
If less than or equal to 0, does not limit the size of the result.
/**
     * <p>Limits the size of the returned list.  The call to
     * <code>getRows()</code> will return at most limit number of rows.
     * If less than or equal to 0, does not limit the size of the result.
     */
    protected int limit = -1;

    
The list of DynaBeans representing the contents of the original ResultSet on which this RowSetDynaClass was based.
/**
     * <p>The list of {@link DynaBean}s representing the contents of
     * the original <code>ResultSet</code> on which this
     * {@link RowSetDynaClass} was based.</p>
     */
    protected List<DynaBean> rows = new ArrayList<DynaBean>();

    // ----------------------------------------------------------- Constructors


    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to column names in the result set will be lower cased.
Params:
resultSet – The result set to be wrapped
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to column names in the result set will be lower cased.</p>
     *
     * @param resultSet The result set to be wrapped
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     */
    public RowSetDynaClass(final ResultSet resultSet) throws SQLException {

        this(resultSet, true, -1);

    }

    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to column names in the result set will be lower cased.
If limit is not less than 0, max limit
number of rows will be copied into the list.
Params:
resultSet – The result set to be wrapped
limit – The maximum for the size of the result.
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to column names in the result set will be lower cased.</p>
     *
     * If <code>limit</code> is not less than 0, max <code>limit</code>
     * number of rows will be copied into the list.
     *
     * @param resultSet The result set to be wrapped
     * @param limit The maximum for the size of the result.
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     */
    public RowSetDynaClass(final ResultSet resultSet, final int limit) throws SQLException {

        this(resultSet, true, limit);

    }


    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to the column names in the result set will be lower cased or not,
depending on the specified lowerCase value.
If limit is not less than 0, max limit
number of rows will be copied into the resultset.
Params:
resultSet – The result set to be wrapped
lowerCase – Should property names be lower cased?
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to the column names in the result set will be lower cased or not,
     * depending on the specified <code>lowerCase</code> value.</p>
     *
     * If <code>limit</code> is not less than 0, max <code>limit</code>
     * number of rows will be copied into the resultset.
     *
     *
     * @param resultSet The result set to be wrapped
     * @param lowerCase Should property names be lower cased?
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     */
    public RowSetDynaClass(final ResultSet resultSet, final boolean lowerCase)
                                                    throws SQLException {
        this(resultSet, lowerCase, -1);

    }

    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to the column names in the result set will be lower cased or not,
depending on the specified lowerCase value.
WARNING - If you specify false
for lowerCase, the returned property names will
exactly match the column names returned by your JDBC driver.
Because different drivers might return column names in different
cases, the property names seen by your application will vary
depending on which JDBC driver you are using.
Params:
resultSet – The result set to be wrapped
lowerCase – Should property names be lower cased?
limit – Maximum limit for the List of DynaBean
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to the column names in the result set will be lower cased or not,
     * depending on the specified <code>lowerCase</code> value.</p>
     *
     * <p><strong>WARNING</strong> - If you specify <code>false</code>
     * for <code>lowerCase</code>, the returned property names will
     * exactly match the column names returned by your JDBC driver.
     * Because different drivers might return column names in different
     * cases, the property names seen by your application will vary
     * depending on which JDBC driver you are using.</p>
     *
     * @param resultSet The result set to be wrapped
     * @param lowerCase Should property names be lower cased?
     * @param limit Maximum limit for the <code>List</code> of {@link DynaBean}
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     */
    public RowSetDynaClass(final ResultSet resultSet, final boolean lowerCase, final int limit)
                                                            throws SQLException {

        this(resultSet, lowerCase, limit, false);

    }

    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to the column names in the result set will be lower cased or not,
depending on the specified lowerCase value.
WARNING - If you specify false
for lowerCase, the returned property names will
exactly match the column names returned by your JDBC driver.
Because different drivers might return column names in different
cases, the property names seen by your application will vary
depending on which JDBC driver you are using.
Params:
resultSet – The result set to be wrapped
lowerCase – Should property names be lower cased?
useColumnLabel – true if the column label should be used, otherwise false
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected
Since:
1.8.3/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to the column names in the result set will be lower cased or not,
     * depending on the specified <code>lowerCase</code> value.</p>
     *
     * <p><strong>WARNING</strong> - If you specify <code>false</code>
     * for <code>lowerCase</code>, the returned property names will
     * exactly match the column names returned by your JDBC driver.
     * Because different drivers might return column names in different
     * cases, the property names seen by your application will vary
     * depending on which JDBC driver you are using.</p>
     *
     * @param resultSet The result set to be wrapped
     * @param lowerCase Should property names be lower cased?
     * @param useColumnLabel true if the column label should be used, otherwise false
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     * @since 1.8.3
     */
    public RowSetDynaClass(final ResultSet resultSet, final boolean lowerCase, final boolean useColumnLabel)
        throws SQLException {
        this(resultSet, lowerCase, -1, useColumnLabel);

    }

    
Construct a new RowSetDynaClass for the specified ResultSet.  The property names corresponding
to the column names in the result set will be lower cased or not,
depending on the specified lowerCase value.
WARNING - If you specify false
for lowerCase, the returned property names will
exactly match the column names returned by your JDBC driver.
Because different drivers might return column names in different
cases, the property names seen by your application will vary
depending on which JDBC driver you are using.
Params:
resultSet – The result set to be wrapped
lowerCase – Should property names be lower cased?
limit – Maximum limit for the List of DynaBean
useColumnLabel – true if the column label should be used, otherwise false
Throws:
NullPointerException – if resultSet
 is null
SQLException – if the metadata for this result set
 cannot be introspected
Since:
1.8.3/**
     * <p>Construct a new {@link RowSetDynaClass} for the specified
     * <code>ResultSet</code>.  The property names corresponding
     * to the column names in the result set will be lower cased or not,
     * depending on the specified <code>lowerCase</code> value.</p>
     *
     * <p><strong>WARNING</strong> - If you specify <code>false</code>
     * for <code>lowerCase</code>, the returned property names will
     * exactly match the column names returned by your JDBC driver.
     * Because different drivers might return column names in different
     * cases, the property names seen by your application will vary
     * depending on which JDBC driver you are using.</p>
     *
     * @param resultSet The result set to be wrapped
     * @param lowerCase Should property names be lower cased?
     * @param limit Maximum limit for the <code>List</code> of {@link DynaBean}
     * @param useColumnLabel true if the column label should be used, otherwise false
     *
     * @throws NullPointerException if <code>resultSet</code>
     *  is <code>null</code>
     * @throws SQLException if the metadata for this result set
     *  cannot be introspected
     * @since 1.8.3
     */
    public RowSetDynaClass(final ResultSet resultSet, final boolean lowerCase, final int limit, final boolean useColumnLabel)
                                                            throws SQLException {

        if (resultSet == null) {
            throw new NullPointerException();
        }
        this.lowerCase = lowerCase;
        this.limit = limit;
        setUseColumnLabel(useColumnLabel);
        introspect(resultSet);
        copy(resultSet);

    }

    
Return a List containing the DynaBeans that represent the contents of each Row from the
ResultSet that was the basis of this RowSetDynaClass instance. These DynaBeans are disconnected from the database itself, so there is no problem with modifying the contents of the list, or the values of the properties of these DynaBeans. However, it is the application's responsibility to persist any such changes back to the database, if it so desires.
Returns:
A List of DynaBean instances/**
     * <p>Return a <code>List</code> containing the {@link DynaBean}s that
     * represent the contents of each <code>Row</code> from the
     * <code>ResultSet</code> that was the basis of this
     * {@link RowSetDynaClass} instance.  These {@link DynaBean}s are
     * disconnected from the database itself, so there is no problem with
     * modifying the contents of the list, or the values of the properties
     * of these {@link DynaBean}s.  However, it is the application's
     * responsibility to persist any such changes back to the database,
     * if it so desires.</p>
     *
     * @return A <code>List</code> of {@link DynaBean} instances
     */
    public List<DynaBean> getRows() {

        return (this.rows);

    }


    // ------------------------------------------------------ Protected Methods


    
Copy the column values for each row in the specified
ResultSet into a newly created DynaBean, and add this bean to the list of DynaBeans that will later by returned by a call to getRows().
Params:
resultSet – The ResultSet whose data is to be
 copied
Throws:
SQLException – if an error is encountered copying the data/**
     * <p>Copy the column values for each row in the specified
     * <code>ResultSet</code> into a newly created {@link DynaBean}, and add
     * this bean to the list of {@link DynaBean}s that will later by
     * returned by a call to <code>getRows()</code>.</p>
     *
     * @param resultSet The <code>ResultSet</code> whose data is to be
     *  copied
     *
     * @throws SQLException if an error is encountered copying the data
     */
    protected void copy(final ResultSet resultSet) throws SQLException {

        int cnt = 0;
        while (resultSet.next() && (limit < 0  || cnt++ < limit) ) {
            final DynaBean bean = createDynaBean();
            for (DynaProperty propertie : properties) {
                final String name = propertie.getName();
                final Object value = getObject(resultSet, name);
                bean.set(name, value);
            }
            rows.add(bean);
        }

    }


    
Create and return a new DynaBean instance to be used for representing a row in the underlying result set.
Returns:
A new DynaBean instance/**
     * <p>Create and return a new {@link DynaBean} instance to be used for
     * representing a row in the underlying result set.</p>
     *
     * @return A new <code>DynaBean</code> instance
     */
    protected DynaBean createDynaBean() {

        return (new BasicDynaBean(this));

    }


}