foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/platform/database/converters/StructConverter.java

/*
 * Copyright (c) 1998, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.platform.database.converters;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Struct;

/**
 * PUBLIC:
 * A StuctConverter can be added to a DatabasePlatform
 * It allows custom processing dealing java.sql.Struct types
 * When added to the DatabasePlatform:
 * 1. convertToObject(Struct) will be invoked
 * when a Struct named by the value returned by getStructName() is returned from the database.  This
 * conversion happens immediately after the object is returned from the database
 * 2. convertToStruct(Object, Connection) will be invoked when an Object of the class
 * returned by getJavaType() is written to the database.  This conversion happens immediately before the
 * object is written to the database
 *
 * Note: Many Structs can also be mapped with mappings StructureMapping and ObjectRelationalDataTypeDescriptor
 * This class provides support for advanced types of Structures that require some processing immediately
 * before writing to the database or immediately after reading from the database.
 *
 * @see org.eclipse.persistence.mappings.structures.StructureMapping
 * @see org.eclipse.persistence.mappings.structures.ObjectRelationalDataTypeDescriptor
 */
public interface StructConverter {

    /**
     * PUBLIC:
     * @return The value return by getSQLTypeName() called when called on the appropriate Struct
     */
    String getStructName();

    /**
     * PUBLIC:
     * @return The Java Class to perform conversions on
     */
    Class getJavaType();

    /**
     * PUBLIC:
     * This method will be invoked internally when reading a Struct from the database
     * Implementers should put any custom conversion logic in this method
     * @param struct the Struct that will be read
     * @return The Object converted back from the Struct
     */
    Object convertToObject(Struct struct) throws SQLException;

    /**
     * PUBLIC:
     * This method will be invoked internally when writing an Object to the database
     * Implementers should put any custom conversion logic in this method
     * @param struct The Object to convert
     * @param connection The JDBC connection
     * @return The Object as a Struct
     */
    Struct convertToStruct(Object struct,
                           Connection connection) throws SQLException;
}