RecordBufferSerializer.java
/*
** Module : RecordBufferSerializer.java
** Abstract : Handles serialization of RecordBuffer objects.
**
** Copyright (c) 2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description---------------------------------------
** 001 AP 20250129 Created initial version.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
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*/
package com.goldencode.p2j.persist;
import com.goldencode.p2j.persist.orm.*;
import java.sql.*;
import java.time.*;
import java.util.*;
/**
* {@link RecordBufferSerializer} objects are used for retrieving the data from the SQL table(s) associated to
* a {@link RecordBuffer}. Method {@link RecordBufferSerializer#sqlTableContent} returns the data as a Map,
* that can be further serialized.
*/
public class RecordBufferSerializer
{
/** {@link Session} associated with the serialized {@link RecordBuffer} */
private final Session session;
/** {@link DmoMeta} associated with the serialized {@link RecordBuffer} */
private final DmoMeta dmoInfo;
/** List of normalized extent fields */
private final List<Property> normalizedFields;
/** Mapping from lowercased SQL column names from {@link Property#column} to the actual {@link Property} */
private final Map<String, Property> sqlNameNormalizedFields;
/** Flag to indicate whether the legacy column names should be used or the SQL ones */
private final boolean useLegacyFieldsName;
/** Map that represents the current row that is being populated. The keys are the column's names and the
* values represent either Strings when the column holds scalars or List<String> when it holds extents */
private Map<String, Object> currentRowObject;
/**
* Constructor for {@link RecordBufferSerializer}.
*
* @param recordBuffer
* The {@link RecordBuffer} for which the associated SQL table needs to be serialized
* @param useLegacyFieldsName
* Flag used to set whether the SQL field names should be used or the legacy ones
*/
public RecordBufferSerializer(RecordBuffer recordBuffer, boolean useLegacyFieldsName)
{
this.dmoInfo = recordBuffer.getDmoInfo();
this.session = recordBuffer.getPersistence().getSession(!dmoInfo.multiTenant);
this.normalizedFields = new ArrayList<>();
this.useLegacyFieldsName = useLegacyFieldsName;
this.sqlNameNormalizedFields = new HashMap<>();
}
/** Constructor for {@link RecordBufferSerializer} with the
* {@link RecordBufferSerializer#useLegacyFieldsName} set to true by default.
*
* @param recordBuffer
* The {@link RecordBuffer} for which the associated SQL table needs to be serialized
*/
public RecordBufferSerializer(RecordBuffer recordBuffer)
{
this(recordBuffer, true);
}
/**
* Get the content of the SQL table associated with this buffer as a List of Maps. A Map represents a
* record. The key is the field name. The value is either a scalar or a List of strings representing an
* extent.
*
* @return List of Maps, where the key is the field name and the value is a String representing a scalar
* value or a List of Strings representing the extent values
*
* @throws PersistenceException
* If the JDBC connection has been closed or there was an error checking its status.
* @throws SQLException
* If a database access error occurs, or if any of the SQL operations (preparation, execution, or
* result handling) fail
*/
public List<Map<String, Object>> sqlTableContent()
throws PersistenceException, SQLException
{
Connection conn = this.session.getConnection();
List<Map<String, Object>> results = new ArrayList<>();
try (PreparedStatement ps = conn.prepareStatement("select * from " + dmoInfo.sqlTable);
ResultSet res = ps.executeQuery())
{
while (res.next())
{
currentRowObject = new HashMap<>();
results.add(currentRowObject);
handleSqlRow(res);
addNormalizedExtentFields(conn, res.getInt(1));
}
}
return results;
}
/**
* Iterates over all the fields from the associated DMO and populates the
* {@link RecordBufferSerializer#currentRowObject} with data ONLY from the main table. It doesn't handle
* the tables where the extent values are saved. In this method ONLY the scalar values and the denormalized
* fields are handled.
*
* @param resultSet
* The current {@code ResultSet}
*
* @throws SQLException
* If a database access error occurs, or if any of the SQL operations (preparation, execution, or
* result handling) fail
*/
@SuppressWarnings("unchecked")
private void handleSqlRow(ResultSet resultSet)
throws SQLException
{
Iterator<Property> fieldsIterator = dmoInfo.getFields(false);
while (fieldsIterator.hasNext())
{
Property field = fieldsIterator.next();
String label = getFieldName(field);
// this is a scalar value
if (field.extent == 0)
{
String value = getFullValueForField(resultSet, field);
currentRowObject.put(label, value);
}
// this is an extent, but denormalized, so the data is in the same table
else if (field.denormalized)
{
String value = getFullValueForField(resultSet, field);
List<String> currentValuesForExtent = (List<String>) currentRowObject.get(label);
if (currentValuesForExtent == null)
{
currentValuesForExtent = new ArrayList<>();
currentRowObject.put(label, currentValuesForExtent);
}
currentValuesForExtent.add(value);
}
// this is normalized extent, and on the first row in the resultSet
else if (resultSet.isFirst())
{
// 'cache' the normalized fields for further usage
sqlNameNormalizedFields.put(field.column.toLowerCase(), field);
normalizedFields.add(field);
}
}
}
/**
* Gets the full value for a field in the {@link ResultSet}, handling the case where the field is of type
* datetime-tz.
*
* @param resultSet
* The current {@code ResultSet}
* @param field
* The {@link Property} for which to retrieve the value
*
* @return Full value for a field in the {@link ResultSet} or null if SQL value is NULL
*
* @throws SQLException
* If the columnLabel is not valid; if a database access error occurs or this method is called on a
* closed result set
*/
private String getFullValueForField(ResultSet resultSet, Property field)
throws SQLException
{
if (resultSet.getString(field.column) == null)
{
return null;
}
if (!field._isDatetimeTz)
{
return resultSet.getString(field.column);
}
Timestamp tt = resultSet.getTimestamp(field.column);
if (tt == null)
{
return null;
}
else
{
int offset = resultSet.getInt(field.column + DDLGeneratorWorker.DTZ_OFFSET); // DTZ_OFFSET
ZoneOffset zoneOffset = ZoneOffset.ofHoursMinutes(offset / 60, offset % 60);
OffsetDateTime offsetDateTime = OffsetDateTime.ofInstant(tt.toInstant(), zoneOffset);
return offsetDateTime.toString();
}
}
/**
* Adds the normalized extent fields to {@link RecordBufferSerializer#currentRowObject}. It first adds the
* field names as key in the {@link RecordBufferSerializer#currentRowObject} map. Then, iterates through
* all the sqls used to load the table data and populates the lists in the map using
* {@link RecordBufferSerializer#handleSqlNormalizedRow(ResultSet)}.
*
* @param conn
* The {@link Connection} object used to interact with the database
* @param rowId
* The ID of the row for which to fetch and process data
*
* @throws SQLException
* If a database access error occurs, or if any of the SQL operations (preparation, execution, or
* result handling) fail
*/
private void addNormalizedExtentFields(Connection conn, int rowId)
throws SQLException
{
for (Property normalizedField : normalizedFields)
{
currentRowObject.put(getFieldName(normalizedField), new ArrayList<>());
}
String[] sqls = dmoInfo.getRecordMeta().getLoadSql();
for (int i = 1; i < sqls.length; i++)
{
try (PreparedStatement ps = conn.prepareStatement(sqls[i]))
{
ps.setInt(1, rowId);
try (ResultSet res = ps.executeQuery())
{
while (res.next())
{
handleSqlNormalizedRow(res);
}
}
}
}
}
/**
* Iterates through the columns in the associated with the {@link ResultSet} and if the column exists in
* {@link RecordBufferSerializer#sqlNameNormalizedFields}, adds the value in the List from
* {@link RecordBufferSerializer#currentRowObject} for this extent.
* NOTE: this method assumes the {@link RecordBufferSerializer#currentRowObject} already contains the
* field name and the associated value is a List. This method does not handle scenarios when this is not
* true.
*
* @param resultSet
* The current {@code ResultSet}
*
* @throws SQLException
* If a database access error occurs
*/
@SuppressWarnings("unchecked")
private void handleSqlNormalizedRow(ResultSet resultSet)
throws SQLException
{
ResultSetMetaData metaData = resultSet.getMetaData();
int columnCount = metaData.getColumnCount();
for (int i = 1; i <= columnCount; i++)
{
String columnName = metaData.getColumnLabel(i).toLowerCase();
Property field = sqlNameNormalizedFields.get(columnName);
if (field == null)
{
continue;
}
List<String> currentValuesForExtent = (List<String>) currentRowObject.get(getFieldName(field));
String value = getFullValueForField(resultSet, field);
currentValuesForExtent.add(value);
}
}
/**
* Gets the field name based on the flag {@link RecordBufferSerializer#useLegacyFieldsName}.
*
* @param field
* The field for which to the get name
*
* @return See above
*/
private String getFieldName(Property field)
{
if (useLegacyFieldsName)
{
return field.legacy;
}
return field.column;
}
}