[FIXED] Multiple ObjectMappers for different parts of API

Issue

Currently I have a @Bean configuration in my Spring Boot App like that:

@Bean
public ObjectMapper objectMapper() {
    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    mapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true);
    mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

    mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.NONE);
    mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);

    return mapper;
}

Is it possible to have different ObjectMappers for different parts of the API? I am interested for example to have different property naming strategy for different parts of the API. I want a part of my API (e.g /api/v1/snake/**) to work with SNAKE_CASE and a part of it (e.g /api/v1/camel/**) to work with LOWER_CAMEL_CASE.

Thanks!

Solution

If both parts of the API are not dealing with the same domain objects, you'll be able to do it by providing your own implementation of MappingJackson2HttpMessageConverter that overwrite the canRead and canWrite methods. Here an example using the base package of the object which must be serialized :

Custom converter :

public class CustomConverter extends MappingJackson2HttpMessageConverter {

    private String basePackage;

    public CustomConverter(String basePackage) {
        this.basePackage = basePackage;
    }

    @Override
    public boolean canRead(Type type, Class<?> contextClass, MediaType mediaType) {
        if (contextClass.getName().startsWith(basePackage)) {
            return super.canRead(type, contextClass, mediaType);
        }
        return false;
    }

    @Override
    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
        if (clazz.getName().startsWith(basePackage)) {
            return super.canWrite(clazz, mediaType);
        }
        return false;
    }
}

Configuration

@Configuration
public class Configuration {

    @Bean
    public MappingJackson2HttpMessageConverter camelCaseConverter() {
        MappingJackson2HttpMessageConverter converter = new CustomConverter("package.camel");
        converter.setObjectMapper(camelCaseObjectMapper());
        return converter;
    }

    @Bean
    public MappingJackson2HttpMessageConverter snakeCaseConverter() {
        MappingJackson2HttpMessageConverter converter = new CustomConverter("package.snake");
        converter.setObjectMapper(snakeCaseObjectMapper());
        return converter;
    }

    @Bean
    public ObjectMapper camelCaseObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true);
        mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.NONE);
        mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
        mapper.setPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CAMEL_CASE);

        return mapper;
    }

    @Bean
    public ObjectMapper snakeCaseObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true);
        mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.NONE);
        mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
        mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);

        return mapper;
    }
}

Answered By - Jean-Philippe Bond
Answer Checked By - Clifford M. (JavaFixing Volunteer)