Wrong serialization results while serializing object containing Map<String,Object> #229

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1. komamitsu commented on May 16, 2015

   

   komamitsu

   on May 16, 2015

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   MessagePack needs to know that logger is an instance of Loggers and roTimer is an instance of TransactionTimer but Map<String, Object> doesn't include those information. One option is to create and use a POJO instead of Map<String, Object> like this.

   class DataMap {
     public String request;
     public boolean forced;
     public Loggers logger;
     public TransactionTimer roTimer;
       :
   }
   
     DataMap dataMap = objectMapper.readValue(serializedData, DataMap.class);
   
2. Anand-J-Kadhi commented on May 21, 2015

   

   Anand-J-Kadhi

   on May 21, 2015

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   Can you suggest any other option as this would be a lot big change this time. Like the XstreamSerilaizer(xstream.codehaus.org) serializes.
3. xerial

   added this to the v07 milestone on Jun 23, 2015
4. komamitsu commented on Aug 9, 2015

   

   komamitsu

   on Aug 9, 2015

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   @Anand-J-Kadhi Sorry for the late reply. How about storing Class information into serialized data like this ? You need to write serde, though.

       static class Loggers
       {
           private String name;
           private List<String> instances = new ArrayList<>();
   
           public List<String> getInstances()
           {
               return instances;
           }
   
           public void setInstances(List<String> instances)
           {
               this.instances = instances;
           }
   
           public String getName()
           {
               return name;
           }
   
           public void setName(String name)
           {
               this.name = name;
           }
       }
   
   
       @JsonSerialize(using=MessageDataSerializer.class)
       @JsonDeserialize(using=MessageDataDeserializer.class)
       static class MessageData
       {
           private String accountDn;
           private Map<String, Object> dataMap;
   
           public String getAccountDn()
           {
               return accountDn;
           }
   
           public void setAccountDn(String accountDn)
           {
               this.accountDn = accountDn;
           }
   
           public Map<String, Object> getDataMap()
           {
               return dataMap;
           }
   
           public void setDataMap(Map<String, Object> dataMap)
           {
               this.dataMap = dataMap;
           }
       }
   
       static class MessageDataSerializer
               extends JsonSerializer<MessageData>
       {
           @Override
           public void serialize(MessageData value, JsonGenerator gen, SerializerProvider serializers)
                   throws IOException, JsonProcessingException
           {
               MessageData messageData = (MessageData) value;
               gen.writeStartObject();
               gen.writeObjectField("accountDn", messageData.getAccountDn());
               HashMap<String, String> metadata = new HashMap<>();
               for (Map.Entry<String, Object> entry : messageData.getDataMap().entrySet()) {
                   metadata.put(entry.getKey(), entry.getValue().getClass().getName());
               }
               gen.writeObjectField("__metadata", metadata);
               gen.writeObjectField("dataMap", messageData.getDataMap());
               gen.writeEndObject();
           }
       }
   
       static class MessageDataDeserializer
           extends JsonDeserializer<MessageData>
       {
           @Override
           public MessageData deserialize(JsonParser p, DeserializationContext ctxt)
                   throws IOException, JsonProcessingException
           {
               MessageData messageData = new MessageData();
               TreeNode treeNode = p.readValueAsTree();
   
               TreeNode accountDn = treeNode.get("accountDn");
               messageData.setAccountDn(accountDn.traverse(p.getCodec()).readValueAs(String.class));
   
               Map<String, String> metadata = treeNode.get("__metadata").traverse(p.getCodec()).readValueAs(new TypeReference<Map<String, String>>(){});
               TreeNode dataMapTree = treeNode.get("dataMap");
               Map<String, Object> dataMap = new HashMap<>();
               for (Map.Entry<String, String> entry : metadata.entrySet()) {
                   try {
                       Object o = dataMapTree.get(entry.getKey()).traverse(p.getCodec()).readValueAs(Class.forName(entry.getValue()));
                       dataMap.put(entry.getKey(), o);
                   }
                   catch (ClassNotFoundException e) {
                       throw new RuntimeException("Failed to deserialize: " + entry, e);
                   }
               }
               messageData.setDataMap(dataMap);
   
               return messageData;
           }
       }
   
       public static void main(String[] argv)
               throws IOException
       {
           MessageData messageData = new MessageData();
           messageData.setAccountDn("1234");
           HashMap<String, Object> hashMap = new HashMap<>();
           hashMap.put("pi", 3.14);
           Loggers loggers = new Loggers();
           loggers.setName("foo loggers");
           loggers.setInstances(Arrays.asList("first", "second", "third"));
           hashMap.put("logger", loggers);
           messageData.setDataMap(hashMap);
           ObjectMapper objectMapper = new ObjectMapper(new MessagePackFactory());
           byte[] bytes = objectMapper.writeValueAsBytes(messageData);
           MessageData deserialized = objectMapper.readValue(bytes, MessageData.class);
           Loggers deserializedLogger = (Loggers) deserialized.getDataMap().get("logger");
   

   This way will be available in the next release.
5. Anand-J-Kadhi commented on Aug 9, 2015

   

   Anand-J-Kadhi

   on Aug 9, 2015

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   Hi @komamitsu ,

   No issues , Thanks for this detailed answer.
6. Anand-J-Kadhi

   closed this as completedon Aug 9, 2015