How to restrict jackson from parsing millis to LocalDate in json request

Question

I need to validate LocalDate fields in json requests. What i want is to prevent deserializing numbers as miilis to LocalDate. Here is example:

I have an entity:

public class Test {

   @NotNull
   @JsonFormat(pattern = "yyyy-MM-dd")
   private LocalDate birthDate;

   //getter and setter of course

}

Jackson2ObjectMapperBuilder config:

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.serializationInclusion(JsonInclude.Include.NON_EMPTY);
    builder.featuresToEnable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
    builder.featuresToEnable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
    builder.featuresToDisable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
    builder.modulesToInstall(new JavaTimeModule());
    return builder;
}

Now if i'm receiveing:

{
    "birthDate": 1
}

the result is birthDate=1970-01-02

I'm able to do so by setting leniency to false:

objectMapper.configOverride(LocalDate.class).setFormat(JsonFormat.Value.forLeniency(false));
objectMapper.configOverride(LocalDateTime.class).setFormat(JsonFormat.Value.forLeniency(false));

And then it's working by throwing MismatchedInputException

But it's a little brutal to backward compatibility of our service, because we need to change all our date patterns from "yyyy-MM-dd" to "uuuu-MM-dd" and i wonder is there some solution to say jackson "If you see numbers or anything different from the pattern while deserialization, throw an exception"

Answer 1

You could write a custom LocalDateDeserializer:

public class MyLocalDateDeserializer extends JsonDeserializer<LocalDate> implements ContextualDeserializer {

    private LocalDateDeserializer defaultDeserializer = new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd"));

    public MyLocalDateDeserializer() {
        super();
    }

    public MyLocalDateDeserializer(LocalDateDeserializer defaultDeserializer) {
        super();
        this.defaultDeserializer = defaultDeserializer;
    }


    @Override
    public LocalDate deserialize(JsonParser parser, DeserializationContext context) throws IOException
    {
        if (StringUtils.isNumeric(parser.getText())) {
            throw  JsonMappingException.from(parser, "Not a String representation of Date ");

        }
        return defaultDeserializer.deserialize(parser, context);
    }


    @Override
    public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
            BeanProperty property) throws JsonMappingException
    {
        JsonFormat.Value format = findFormatOverrides(ctxt, property, handledType());
        return (format == null) ? this : new MyLocalDateDeserializer(new LocalDateDeserializer(DateTimeFormatter.ofPattern(format.getPattern())));
    }

    protected JsonFormat.Value findFormatOverrides(DeserializationContext ctxt,
            BeanProperty prop, Class<?> typeForDefaults)
    {
        if (prop != null) {
            return prop.findPropertyFormat(ctxt.getConfig(), typeForDefaults);
        }
        // even without property or AnnotationIntrospector, may have type-specific defaults
        return ctxt.getDefaultPropertyFormat(typeForDefaults);
    }

}

and register it when needed.

Here my simple Tests:

@Test()
public void testObjectMapperForLocalDate() throws IOException {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    JavaTimeModule javaTimeModule = new JavaTimeModule();
    javaTimeModule.addDeserializer(LocalDate.class, new MyLocalDateDeserializer());
    builder.modulesToInstall(javaTimeModule);
    ObjectMapper objectMapper =  builder.build();

       DateContainer container =  objectMapper.readValue("{\r\n" +
                "    \"birthDate\": \"1999-01-01\"\r\n" +
                "}", DateContainer.class);
           System.out.println(container.getBirthDate());
}

@Test()
public void testFailObjectMapperForLocalDate() throws IOException {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    JavaTimeModule javaTimeModule = new JavaTimeModule();
    javaTimeModule.addDeserializer(LocalDate.class, new MyLocalDateDeserializer());
    builder.modulesToInstall(javaTimeModule);
    ObjectMapper objectMapper =  builder.build();

    assertThrows(JsonMappingException.class, () -> {
       DateContainer container =  objectMapper.readValue("{\r\n" +
                "    \"birthDate\": 1\r\n" +
                "}", DateContainer.class);
           System.out.println(container.getBirthDate());
      });
}

EDIT

Deserializer uses Pattern