001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.appender.db.jpa.converter;
018
019import java.io.IOException;
020import java.util.List;
021
022import javax.persistence.AttributeConverter;
023import javax.persistence.Converter;
024import javax.persistence.PersistenceException;
025
026import org.apache.logging.log4j.ThreadContext;
027import org.apache.logging.log4j.spi.DefaultThreadContextStack;
028import org.apache.logging.log4j.util.Strings;
029
030import com.fasterxml.jackson.core.type.TypeReference;
031
032/**
033 * A JPA 2.1 attribute converter for 
034 * {@link org.apache.logging.log4j.ThreadContext.ContextStack ThreadContext.ContextStack}s in
035 * {@link org.apache.logging.log4j.core.LogEvent}s. This converter is capable of converting both to and from
036 * {@link String}s.
037 *
038 * In addition to other optional dependencies required by the JPA appender, this converter requires the Jackson Data
039 * Processor.
040 */
041@Converter(autoApply = false)
042public class ContextStackJsonAttributeConverter implements AttributeConverter<ThreadContext.ContextStack, String> {
043    @Override
044    public String convertToDatabaseColumn(final ThreadContext.ContextStack contextStack) {
045        if (contextStack == null) {
046            return null;
047        }
048
049        try {
050            return ContextMapJsonAttributeConverter.OBJECT_MAPPER.writeValueAsString(contextStack.asList());
051        } catch (final IOException e) {
052            throw new PersistenceException("Failed to convert stack list to JSON string.", e);
053        }
054    }
055
056    @Override
057    public ThreadContext.ContextStack convertToEntityAttribute(final String s) {
058        if (Strings.isEmpty(s)) {
059            return null;
060        }
061
062        List<String> list;
063        try {
064            list = ContextMapJsonAttributeConverter.OBJECT_MAPPER.readValue(s, new TypeReference<List<String>>() { });
065        } catch (final IOException e) {
066            throw new PersistenceException("Failed to convert JSON string to list for stack.", e);
067        }
068
069        final DefaultThreadContextStack result = new DefaultThreadContextStack(true);
070        result.addAll(list);
071        return result;
072    }
073}