Spring Boot 1.4 Customize Internal Jackson Deserialization

Question

I am using spring.jackson.deserialization.FAIL_ON_UNKNOWN_PROPERTIES=true in the application.properties to make deserialization fail on unknown properties but its not working.

I even tried using :

@Bean
ObjectMapper objectMapper() {
  return Jackson2ObjectMapperBuilder
        .json()
        .featuresToEnable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
        .build();
}

But this also didn't work. What am I missing?

Answer 1

With Spring boot, by default, unknown properties are ignored during deserialization. In order not to ignore these properties, you can :

• Add spring.jackson.deserialization.FAIL_ON_UNKNOWN_PROPERTIES=true in the application.properties

• Use this bean :

  @Bean
  public ObjectMapper objectMapper() {
      return Jackson2ObjectMapperBuilder
      .json()
      .featuresToEnable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
      .build();
  }
  

• Use this bean :

  @Bean 
  public Jackson2ObjectMapperBuilder objectMapperBuilder(){
      Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
      builder.failOnUnknownProperties(true);
      return builder;
  }
  

I have tested these solutions and it works so there is another problem in your code. Please, can you post your code as ask by javaguy?

Answer 2

FAIL_ON_UNKNOWN_PROPERTIES option is true by default according to Jackson Documentation.

If you want to disable this setting you may add this option to application.properties.

spring.jackson.deserialization.fail-on-unknown-properties = false

But in default settings it works as expected. So no need for any setting.

This is one file spring boot application:

@RestController
@SpringBootApplication
public class TestOptionApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestOptionApplication.class, args);
    }

    @PostMapping("/test")
    public void formTest(@RequestBody final HelloForm form) {
    }

    public static class HelloForm {

        private String name;

        public String getName() { return name; }

        public void setName(final String name) { this.name = name; }
    }
}

This is the integration test for testing rejection on unknown properties.

@RunWith(SpringRunner.class)
@SpringBootTest
public class TestOptionApplicationTest {

    @Autowired
    private WebApplicationContext context;

    @Test
    public void testFailOnUnknownPropertiesOption() throws Exception {

        final String text = "{\"name\": \"test\", \"title\": \"test\"}";

        MockMvcBuilders
            .webAppContextSetup(this.context)
            .build()
            .perform(post("/test").contentType(MediaType.APPLICATION_JSON).content(text))
            .andExpect(status().isBadRequest());
    }
}

title property is not defined. So controller sends BadRequest.