/*
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* BaseLink - Generic object relational mapping
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* Copyright (C) 2024 Ulrich Hilger, http://uhilger.de
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see http://www.gnu.org/licenses/
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*/
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package de.uhilger.baselink;
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import static de.uhilger.baselink.PersistenceManager.NULL_STR;
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import java.sql.Blob;
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import java.sql.ResultSet;
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import java.sql.ResultSetMetaData;
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import java.sql.SQLException;
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import java.sql.Types;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import java.util.TreeMap;
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import java.util.logging.Logger;
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/**
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* Methoden zur Umwandlung von ResultSets in Listen
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*
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* @author Copyright (c) Ulrich Hilger, <a href="http://uhilger.de">http://uhilger.de</a>
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* @author Published under the terms and conditions of
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* the <a href="http://www.gnu.org/licenses/" target="_blank">GNU General Public License</a>
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* @version 1, January 22, 2024
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*/
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public class ListConverter {
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private static final Logger logger = Logger.getLogger(ListConverter.class.getName());
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/**
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* Helper method that converts a ResultSet into a list of lists, one per row,
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* each row is a list of strings
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*
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* @param rs result set to convert
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* @param includeBlobs true when blob columns should be returned, false if not
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* @return a list of list objects, one for each record. An element in the
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* list can be accessed with list.get(recordno).get(fieldno), each element is of type String.
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* This first row has the field names
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* @throws java.sql.SQLException
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*/
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public List<List<String>> toList(ResultSet rs, boolean includeBlobs) throws SQLException {
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List<List<String>> rows = new ArrayList<>();
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ResultSetMetaData meta = rs.getMetaData();
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int columnCount = meta.getColumnCount();
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List<String> header = new ArrayList<>();
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for (int i = 1; i <= columnCount; i++) {
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header.add(meta.getColumnName(i));
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}
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rows.add(header);
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while (rs.next()) {
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List<String> row = new ArrayList<>();
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for (int i = 1; i <= columnCount; i++) {
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String data = null;
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if (meta.getColumnType(i) == Types.BLOB) {
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if (includeBlobs) {
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Blob blob = rs.getBlob(i);
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if(blob != null) {
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data = new String(blob.getBytes((long) 1, (int) blob.length()));
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}
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}
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} else {
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Object o = rs.getObject(i);
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if(o != null) {
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data = o.toString();
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} else {
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data = NULL_STR;
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}
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logger.finest(data);
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}
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row.add(data);
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}
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rows.add(row);
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}
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return rows;
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}
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/**
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* Helper method that maps a ResultSet into a list of maps, one per row
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*
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* @param rs database content to transform
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* @param wantedColumnNames list of columns names to include in the result map
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* @return list of maps, one per column row, with column names as keys
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* @throws SQLException if the connection fails
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*/
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public List<Map<String, Object>> toList(ResultSet rs, List<String> wantedColumnNames) throws SQLException {
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// TODO BLOB handling
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List<Map<String, Object>> rows = new ArrayList<>();
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int numWantedColumns = wantedColumnNames.size();
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while (rs.next()) {
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Map<String, Object> row = new TreeMap<>();
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for (int i = 0; i < numWantedColumns; ++i) {
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String columnName = wantedColumnNames.get(i);
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Object value = rs.getObject(columnName);
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if (value != null) {
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row.put(columnName, value);
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//Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).finest(columnName + " " + value);
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} else {
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row.put(columnName, "");
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}
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}
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rows.add(row);
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}
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return rows;
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}
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/**
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* Helper method that converts a ResultSet into a list of maps, one per row
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*
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* @param rs database content to transform
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* @return list of maps, one per row, with column name as the key
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* @throws SQLException if the connection fails
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*/
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public List<Map<String, Object>> toList(ResultSet rs) throws SQLException {
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List<String> wantedColumnNames = getColumnNames(rs);
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return toList(rs, wantedColumnNames);
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}
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/**
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* Return all column names as a list of strings
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*
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* @param database query result set
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* @return list of column name strings
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* @throws SQLException if the query fails
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*/
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private List<String> getColumnNames(ResultSet rs) throws SQLException {
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List<String> columnNames = new ArrayList<String>();
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ResultSetMetaData meta = rs.getMetaData();
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int numColumns = meta.getColumnCount();
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for (int i = 1; i <= numColumns; ++i) {
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String cName = meta.getColumnName(i);
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columnNames.add(cName);
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}
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return columnNames;
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}
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}
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