    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     */
    017    package org.apache.logging.log4j.core.appender.db.jpa.converter;
    018
    019    import java.io.IOException;
    020    import java.util.List;
    021
    022    import javax.persistence.AttributeConverter;
    023    import javax.persistence.Converter;
    024    import javax.persistence.PersistenceException;
    025
    026    import org.apache.logging.log4j.ThreadContext;
    027    import org.apache.logging.log4j.spi.DefaultThreadContextStack;
    028    import org.apache.logging.log4j.util.Strings;
    029
    030    import 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)
    042    public 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    }