StringListConverter.java

/*
 * Copyright 2005-2024 the original author or authors.
 *
 * 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.
 */
package org.openwms.common.location;

import jakarta.persistence.AttributeConverter;
import jakarta.persistence.Converter;
import jakarta.persistence.PersistenceException;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import static java.lang.String.format;

/**
 * A StringListConverter is a JPA {@link AttributeConverter} that is able to convert a {@code String} into a {@code List} of strings and
 * vice-versa.
 *
 * @author Heiko Scherrer
 */
@Converter
public class StringListConverter implements AttributeConverter<List<String>, String> {

    /** Default length of the string list. */
    public static final int STRING_LIST_LENGTH = 1024;
    /** Default separator sign of a string list. */
    public static final String SEPARATOR = ",";

    /**
     * Return the maximum list length.
     *
     * @see #STRING_LIST_LENGTH
     * @return The maximum list length
     */
    protected int getListLength() {
        return STRING_LIST_LENGTH;
    }

    /**
     * Return the separator that is used to separate the String into a List of Strings.
     *
     * @see #SEPARATOR
     * @return The separator as String
     */
    protected String getSeparator() {
        return SEPARATOR;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String convertToDatabaseColumn(List<String> attribute) {
        if (attribute == null) {
            return null;
        }
        var join = String.join(getSeparator(), attribute);
        if (join.length() > getListLength()) {
            throw new PersistenceException(format("Length of column exceeded, actual length is [%d], allowed is [%d]", join.length(),
                    getListLength()));
        }
        return join;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<String> convertToEntityAttribute(String dbData) {
        if (dbData == null || dbData.isEmpty()) {
            return new ArrayList<>();
        }
        return new ArrayList<>(Arrays.asList(dbData.split(getSeparator())));
    }
}