How to configure MappingJackson2HttpMessageConverter registered by spring-hateoas?

[ceefour]

I'm sorry for misusing the issues as a forum, however there's already this question at StackOverflow http://stackoverflow.com/questions/24694493/how-to-configure-mappingjackson2httpmessageconverter-registered-by-spring-hateoa 3 months old and no solution.

[jcayetano]

Not an easy one, because it's a container of static inner classes. Easier to fork spring-hateoas project and apply your changes locally.

[dilipkrish]

@ceefour you should be able to access/ autowire the "_halObjectMapper" bean (don't remember for sure but I believe that's the qualifier name) in your spring configuration. Then the customizations are straight forward.

[ceefour]

Thanks! Although that feels hacky or internals to me...

Actually the common use case would be to register additional modules such as JodaModule and friends... And also e.g. enable pretty-print JSON during development and disable it for production. Is there any "official" way to do it or planned?

[dschulten]

In my experience, when you need to customize converters and modules it is also necessary to get their order right, and sooner or later you need full control. This is possible using WebMvcConfigurationSupport.configureMessageConverters (xml does not give you the same level of control, at least not in older versions of Spring). By letting your @configuration class extend WebMvcConfigurationSupport you effectively do the same as writing @EnableWebMvc, but you get more control.
You also need to replicate some internal setup logic of spring-hateoas, notably the rel provider plugin registry. Since it took me some time to figure that out, here is what I do:

@Configuration
@EnablePluginRegistries(RelProvider.class)
public class Config extends WebMvcConfigurationSupport {

private static final boolean EVO_PRESENT =
ClassUtils.isPresent("org.atteo.evo.inflector.English", null);

@Autowired
private PluginRegistry<RelProvider, Class<?>> relProviderRegistry;

@Override
protected void configureMessageConverters(List<HttpMessageConverter<?>>
converters) {
... converters that must come before jackson
converters.add(halConverter());
converters.add(jsonConverter());
... more converters
}

@Bean
public ObjectMapper jacksonObjectMapper() {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setSerializationInclusion(Include.NON_NULL);
return objectMapper;
}

@Bean
public MappingJackson2HttpMessageConverter jsonConverter() {
MappingJackson2HttpMessageConverter jacksonConverter = new
MappingJackson2HttpMessageConverter();
jacksonConverter.setSupportedMediaTypes(Arrays.asList(MediaType.valueOf("application/json")));
jacksonConverter.setObjectMapper(jacksonObjectMapper());
return jacksonConverter;
}

@Bean
public CurieProvider curieProvider() {
return new DefaultCurieProvider("your curie prefix", new UriTemplate("your curie base url template"));
}

@Bean
public MappingJackson2HttpMessageConverter halConverter() {
CurieProvider curieProvider = curieProvider();

RelProvider relProvider = new DelegatingRelProvider(relProviderRegistry);
ObjectMapper halObjectMapper = new ObjectMapper();

halObjectMapper.setSerializationInclusion(Include.NON_NULL);

halObjectMapper.registerModule(new Jackson2HalModule());
halObjectMapper.setHandlerInstantiator(new
Jackson2HalModule.HalHandlerInstantiator(relProvider, curieProvider));

MappingJackson2HttpMessageConverter halConverter = new
MappingJackson2HttpMessageConverter();
halConverter.setSupportedMediaTypes(Arrays.asList(MediaTypes.HAL_JSON));
halConverter.setObjectMapper(halObjectMapper);
return halConverter;
}

@Bean
RelProvider defaultRelProvider() {
return EVO_PRESENT ? new EvoInflectorRelProvider() : new DefaultRelProvider();
}

@Bean
RelProvider annotationRelProvider() {
return new AnnotationRelProvider();
}

}

[gregturn]

Superceded by #833.