Json custom deserializer stuck in infinite recursion

Question

Implemented a custom deserializer to deserialize a JSON by the following way. but mapper.treeToValue is causing to call the code infinite number of times.

public class MyDeserializer extends StdDeserializer<MyResource>  {
       @Override
    public myResourcedeserialize(JsonParser parser, DeserializationContext context) throws IOException, JsonProcessingException {
         MyResource resource = null;
        Class<? extends MyResource > clazz = null;
        ObjectMapper mapper = (ObjectMapper) parser.getCodec();
        ObjectNode node = (ObjectNode) mapper.readTree(parser);

        Iterator<Map.Entry<String, JsonNode>> elementsIterator = node.fields();

        while (elementsIterator.hasNext()) {
            Map.Entry<String, JsonNode> element = elementsIterator.next();
            if(element.getKey().equals("typeId"))
            {
                if(element.getValue().asInt() == 1)
                {
                    clazz = SpecificResource.class;
                    break;
                }
            }
        }
        return  mapper.treeToValue(node,clazz);
}

After executing mapper.treeToValue, control again goes back myResourcedeserialize method and executing it infinite number of times and causing stackOverFlowError.

Any suggestions please?

Answer 1

We have faced similar situation and this solution is based on that: The custom de-serializer is used to parse JSON polymorphically without using type attribute

Lets call the polymorphic classes as BaseResource (base class), SubResource1, SubResource2.

BaseResource has annotation to specify which CustomSerializer class

@JsonDeserialze(using=CustomDeserializer.class)
public class BaseResource{
......
}

So on SubResource1 and SubResource2, we add annotations to not use the CustomDeserialzer.class by using JsonDeserialer.None.class

@JsonDeserialze(using=JsonDeserialer.None.class)
public class SubResource1 extends BaseResource{
......
}

Reference: http://www.robinhowlett.com/blog/2015/03/19/custom-jackson-polymorphic-deserialization-without-type-metadata/