How can I deserialize both camel case and snake case in Jackson?

Question

I would like to deserialize json strings that include camel case or snake case as follow.

{"testField":"test"}

or

{"test_field":"test"}

And, I would like to deserialize this json strings by only one ObjectMapper objeect as follow.

public class Test {
    public static void main(final String[] args) throws JsonProcessingException {
        final ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

        System.out.println(objectMapper.readValue("{\"testField\":\"test\"}", Parent.class));
        System.out
                .println(objectMapper.readValue("{\"test_field\":\"test\"}", Parent.class));
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    static class Parent {
        String testField;
    }
}

But, I could deserialize into either a camel case or a snake case.

Additionally, I want only snake case during serialization.

I tried a custom PropertyNamingStrategy.

But it did not work well.

Answer 1

You can use @JsonAlias

class Parent {
    @JsonAlias({ "test_field" })
    String testField;
}