How to enforce ACCEPT_SINGLE_VALUE_AS_ARRAY in jackson's deserialization process using annotation

Question

Is there a way to use annotation on a List property in a class to use ACCEPT_SINGLE_VALUE_AS_ARRAY in Jackson? I\'m using Spring and getting the b

Answer 1

I would create a custom JsonDeserializer where I would deal with both cases and annotate value class property with the deserializer.

Deserializer:

public class StringListDeserializer extends JsonDeserializer>{

    @Override
    public List deserialize(JsonParser parser, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {

        List ret = new ArrayList<>();

        ObjectCodec codec = parser.getCodec();
        TreeNode node = codec.readTree(parser);

        if (node.isArray()){
            for (JsonNode n : (ArrayNode)node){
                ret.add(n.asText());
            }
        } else if (node.isValueNode()){
            ret.add( ((JsonNode)node).asText() );
        }
        return ret;
    }
}

MyClass:

public class MyClass {
    .
    @JsonDeserialize(using = StringListDeserializer.class)
    private List value;
    .
}

Hope it helps.

BTW: If there is a way how to deal with such a case with just an annotation, I also want to know it.