java - 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 below exception

nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of VALUE_STRING token

Assume I have a class as below:

public class MyClass {

    private List < String > value;
}

And my JSON structures are as below:

case 1:

[{"operator": "in", "value": ["Active"], "property": "status"}]

case 2:

[{"operator": "like", "value": "aba", "property": "desc"}]

What annotation should I use to let the framework know I want these 2 cases to be treated the same when deserializing.

UPDATE: I moved the updates to an answer in this post for more clarity.

Answer 1

You can use @JsonFormat annotation,

public class MyClass {

    @JsonFormat(with = JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY)
    private List<String> value;

}

To work with this you need to have Jackson version min 2.7.0. You can also use other available JsonFormat Features

For version 2.6.x

@Autowired private ObjectMapper mapper;
//...

mapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);

• Add this code to your Initializer Class.
• Or you can directly configure Jackson in your Bean Configuration

These would solve the issue but it will be activated for every deserialization process.