converting Document objects in MongoDB 3 to POJOS

Question

I\'m saving an object with a java.util.Date field into a MongoDB 3.2 instance.

ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsStr         


        

Answer 1

It looks like you are using Date object inside "myObject". In that case, you should use a DateSerializer that implements JsonSerializer, JsonDeserializer and then register it with GsonBuilder. Sample code follows:

public class My_DateSerializer implements JsonSerializer,
                                                          JsonDeserializer {

@Override
public LocalDate deserialize(JsonElement json, Type typeOfT,
                        JsonDeserializationContext context) throws JsonParseException {
    final String dateAsString = json.getAsString();
    final DateTimeFormatter dtf = DateTimeFormat.forPattern(DATE_FORMAT);
    if (dateAsString.length() == 0)
    {
        return null;
    }
    else
    {
        return dtf.parseLocalDate(dateAsString);
    }
}

@Override
public JsonElement serialize(LocalDate src, Type typeOfSrc,
                                                     JsonSerializationContext context) {
    String retVal;
    final DateTimeFormatter dtf = DateTimeFormat.forPattern(DATE_FORMAT);
    if (src == null)
    {
        retVal = "";
    }
    else
    {
        retVal = dtf.print(src);
    }
    return new JsonPrimitive(retVal);
}
}

Now register it with GsonBuilder:

final GsonBuilder builder = new GsonBuilder()
           .registerTypeAdapter(LocalDate.class, new My_DateSerializer());      
final Gson gson = builder.create();