Spring Boot and ObjectMapper configuration

Question

Using Spring Boot 1.2.2 to create an Spring MVC application. I am also using Spring HATEOAS.

The issue I am having is that my configured ObjectMapper is used properly when my controller methods return a List<> , but a different ObjectMapper is being used when I return my Resource classes (eg MyClass extends ResourceSupport )

It's a more than a little frustrating to try to configure Jackson's ObjectMapper . I have followed the documentation and added my own ObjectMapper @Bean to a @Configuration class and annotated it with @Primary , and that one is being used when serializing List<> .

Setting a breakpoint in the ObjectMapper constructor breakpoint reveals that the constructor is called about 20 times. I made a poor summary of each scenario:

1. My configuration class ( @Bean annotated with @Primary )
2. halObjectMapper
3. WebMvcConfigurationSupport->requestMappingHandlerAdapter()->AllEncompassingFormHttpMessageConverter->Jackson2ObjectMapperBuilder
4. configureMessageConverters()->Jackson2ObjectMapperBuilder
5. potentiallyRegisterModule()->Jackson2ObjectMapperBuilder
6. WebMvcConfigurationSupport->addDefaultHandlerExceptionResolver()->AllEncompassingFormHttpMessageConverter->Jackson2ObjectMapperBuilder
7. 2 times: WebMvcConfigurationSupport->addDefaultHttpMessageConverters()->AllEncompassingFormHttpMessageConverter->Jackson2ObjectMapperBuilder
8. 12 times: EndpointMBeanExporter (Spring Boot Actuator)

Answer 1

I'd recommend either using application.properties to configure Jackson or, if you need more control, declaring your own Jackson2ObjectMapperBuilder bean. In either case, you end up with a Jackson2ObjectMapperBuilder bean in the application context that can then be used by other components to create ObjectMapper s with your desired configuration or to apply that configuration to any existing ObjectMapper s.

Edit: there's an issue open to improve Actuator's ObjectMapper usage.

Answer 2

You can configure Jackson using spring boot application.properties .

See class org.springframework.boot.autoconfigure.jackson.JacksonProperties or using Spring Tool Suite, simply edit your application.properties , start typing spring.jackson. then hit Ctrl-Space to see the available properties.