Access HAL+JSON resources using RestTemplate from RestTemplateBuilder

[mkhl]

I'm using Spring 5.1.8, Spring Boot 2.1.6, and Spring HATEOAS 0.25.1.

I want to construct the RestTemplate in the using @Component by injecting RestTemplateBuilder.
This seems to be the recommended way and allows different components to define their own error handling instead of sharing it across components.

ConverterRegisteringBeanPostProcessor configures any RestTemplate bean in the application context (using ConverterRegisteringWebMvcConfigurer), but it doesn't affect RestTemplateBuilder.
For that I have to define the following RestTemplateCustomizer (based on this comment):

@Configuration
@EnableHypermediaSupport(type = HAL)
class HalConfiguration {
    @Bean
    RestTemplateCustomizer halRestTemplateCustomizer(ConverterRegisteringWebMvcConfigurer configurer) {
        return template -> configurer.extendMessageConverters(template.getMessageConverters());
    }
}

It seems to me that (something like) this would make sense to include in spring-hateoas.
Alternatively, it would be nice if there were an easier way to access or inject hypermedia-enabled HttpMessageConverters.

[gregturn]

Have you read this?

https://docs.spring.io/spring-hateoas/docs/1.0.0.RC1/reference/html/#mediatypes.custom

[mkhl]

I hadn't, thank you for the link. I'm not sure I see the relevance to RestTemplateBuilder and RestTemplateCustomizer, did you maybe mean to add this to #1050 or #1051?

[rustige]

I am on the same project as @mkhl. Now we use for 1.0.1-RELEASE following workaround to register the HAL converter:

@Configuration
public class RestTemplateConfig {

    @Bean
    RestTemplateCustomizer halRestTemplateCustomizer(List<WebMvcConfigurer> configurers) {
        WebMvcConfigurer webMvcConfigurer = configurers.stream()
                                                       .filter(configurer -> configurer.getClass().getCanonicalName().contains("org.springframework.hateoas"))
                                                       .findFirst()
                                                       .get();
        return template -> webMvcConfigurer.extendMessageConverters(template.getMessageConverters());
    }
}

As WebMvcConfigurer is package-private we cannot access it directly.

[mkhl]

(He means org.springframework.hateoas.config.WebMvcHateoasConfiguration.HypermediaWebMvcConfigurer, which is package-private and is the WebMvcConfigurer we're finding in that code snippet.)