OrientDB将查询结果直接序列化到Json

Question

I have a orient db query and want to pass the result back as json. So I have the following code:

OSQLSynchQuery<ODocument> q = new OSQLSynchQuery<ODocument>(query);
List<ODocument> result = db.command(q).execute();
return new ObjectMapper().writeValueAsString(result);

But since the serialization of ODocument leads to an infinite recursion ( see this SO question ) I have a problem.

Looping the list and concatinating ODocument#toJSON() to a StringBuffer is not my prefered option. Especially since I also have a case where I transform a "group by" result into a hashmap which I want to be json too. So is there a clean way on json serializing ODcomument as part of another object (list or map)?

Answer 1

This is for sure not a very nice way but this is working quite well. First I loop through the result and build a list of json strings:

List<String> jsonResult = new ArrayList<>();
for (ODocument d : queryResult) jsonResult.add(d.toJSON());

Next I have made a custom serializer which is just writing the raw string (json) to the buffer:

public class RawJsonListJacksonSerializer extends JsonSerializer<List<String>> {
    @Override
    public void serialize(List<String> entries, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
        jsonGenerator.writeStartArray();

        for (int i=0; i<entries.size(); i++) {
            jsonGenerator.writeRaw(entries.get(i) == null ? "null" : entries.get(i));
            if (i<entries.size()-1) jsonGenerator.writeRaw(",");
        }

        jsonGenerator.writeEndArray();
    }
}