    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.Map;
    021
    022    import javax.persistence.AttributeConverter;
    023    import javax.persistence.Converter;
    024    import javax.persistence.PersistenceException;
    025
    026    import org.apache.logging.log4j.util.Strings;
    027
    028    import com.fasterxml.jackson.core.type.TypeReference;
    029    import com.fasterxml.jackson.databind.ObjectMapper;
    030
    031    /**
    032     * A JPA 2.1 attribute converter for {@link Map Map&lt;String, String&gt;}s in
    033     * {@link org.apache.logging.log4j.core.LogEvent}s. This converter is capable of converting both to and from
    034     * {@link String}s.
    035     *
    036     * In addition to other optional dependencies required by the JPA appender, this converter requires the Jackson Data
    037     * Processor.
    038     */
    039    @Converter(autoApply = false)
    040    public class ContextMapJsonAttributeConverter implements AttributeConverter<Map<String, String>, String> {
    041        static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
    042
    043        @Override
    044        public String convertToDatabaseColumn(final Map<String, String> contextMap) {
    045            if (contextMap == null) {
    046                return null;
    047            }
    048
    049            try {
    050                return OBJECT_MAPPER.writeValueAsString(contextMap);
    051            } catch (final IOException e) {
    052                throw new PersistenceException("Failed to convert map to JSON string.", e);
    053            }
    054        }
    055
    056        @Override
    057        public Map<String, String> convertToEntityAttribute(final String s) {
    058            if (Strings.isEmpty(s)) {
    059                return null;
    060            }
    061            try {
    062                return OBJECT_MAPPER.readValue(s, new TypeReference<Map<String, String>>() { });
    063            } catch (final IOException e) {
    064                throw new PersistenceException("Failed to convert JSON string to map.", e);
    065            }
    066        }
    067    }