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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements. See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache license, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License. You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the license for the specific language governing permissions and
    15   * limitations under the license.
    16   */
    17  package org.apache.logging.log4j.core.appender.db.jpa.converter;
    18
    19  import java.io.IOException;
    20  import java.util.List;
    21
    22  import javax.persistence.AttributeConverter;
    23  import javax.persistence.Converter;
    24  import javax.persistence.PersistenceException;
    25
    26  import org.apache.logging.log4j.ThreadContext;
    27  import org.apache.logging.log4j.spi.DefaultThreadContextStack;
    28  import org.apache.logging.log4j.util.Strings;
    29
    30  import com.fasterxml.jackson.core.type.TypeReference;
    31
    32  /**
    33   * A JPA 2.1 attribute converter for
    34   * {@link org.apache.logging.log4j.ThreadContext.ContextStack ThreadContext.ContextStack}s in
    35   * {@link org.apache.logging.log4j.core.LogEvent}s. This converter is capable of converting both to and from
    36   * {@link String}s.
    37   *
    38   * In addition to other optional dependencies required by the JPA appender, this converter requires the Jackson Data
    39   * Processor.
    40   */
    41  @Converter(autoApply = false)
    42  public class ContextStackJsonAttributeConverter implements AttributeConverter<ThreadContext.ContextStack, String> {
    43      @Override
    44      public String convertToDatabaseColumn(final ThreadContext.ContextStack contextStack) {
    45          if (contextStack == null) {
    46              return null;
    47          }
    48
    49          try {
    50              return ContextMapJsonAttributeConverter.OBJECT_MAPPER.writeValueAsString(contextStack.asList());
    51          } catch (final IOException e) {
    52              throw new PersistenceException("Failed to convert stack list to JSON string.", e);
    53          }
    54      }
    55
    56      @Override
    57      public ThreadContext.ContextStack convertToEntityAttribute(final String s) {
    58          if (Strings.isEmpty(s)) {
    59              return null;
    60          }
    61
    62          List<String> list;
    63          try {
    64              list = ContextMapJsonAttributeConverter.OBJECT_MAPPER.readValue(s, new TypeReference<List<String>>() { });
    65          } catch (final IOException e) {
    66              throw new PersistenceException("Failed to convert JSON string to list for stack.", e);
    67          }
    68
    69          final DefaultThreadContextStack result = new DefaultThreadContextStack(true);
    70          result.addAll(list);
    71          return result;
    72      }
    73  }