Ignoring Jackon JsonProperty Access for Unit Tests

Question

I use Jackson for serialization/deserialization with my Spring Boot project.

I have a DTO object with the following structure,

public class TestDTO implements Serializable {
    private static final long serialVersionUID = 1L;

    private Long id;

    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private UUID certificateId;

    @NotNull
    private Long orgId;

    @NotNull
    private CertificateType certificateType;

    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    @Valid
    @NotNull
    private PublicCertificateDTO publicCertificate;

    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    @Valid
    private PrivateCertificateDTO privateCertificate;

    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private ZonedDateTime expiryDate;

    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private ZonedDateTime createdDate;

    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private ZonedDateTime updatedDate;
}

Serialization of this object in my unit tests with the following method,

public static byte[] convertObjectToJsonBytes(TestDTO object)
        throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

    JavaTimeModule module = new JavaTimeModule();
    mapper.registerModule(module);

    return mapper.writeValueAsBytes(object);
}

causes fields with WRITE_ONLY access to get ignored (for obvious reasons). So in the serialized object I see null values for publicCertificate and privateCertificate.

I did try setting mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)

Is there any other way to ignore these properties for Unit Tests ?

Answer 1

While the solution specified works, it is an overkill for the requirement. You don't need custom serializers if all you want is to override annotations. Jackson has a mixin feature for such trivial requirements

Consider the following simplified POJO:

public class TestDTO
{
    public String regularAccessProperty;
    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    public String writeAccessProperty;
}

If you want to override the @JsonProperty annotation, you create another POJO that has a variable with the exact same name (or same getter/setter names):

// mixin class that overrides json access annotation
public class UnitTestDTO
{
    @JsonProperty(access = JsonProperty.Access.READ_WRITE)
    public String writeAccessProperty;
}

You associate the original POJO and the mixin via a Simplemodule:

simpleModule.setMixInAnnotation(TestDTO.class, UnitTestDTO.class);