SPRING REST：以JSON格式从响应中删除空对象

Question

I don't have option of spring.xml so i went by annotated method.

I have below REST Interfaces in package : com.dpk.cm.impl.ecommerce.rest and implementation in com.dpk.cm.impl.ecommerce.rest.services

I created one spring config class: but seems like i am still seeing in my JSON response empty objects.

Below is my code :

@Configuration
@ComponentScan(basePackages = "com.dpk.cm.impl.ecommerce.rest")
@EnableWebMvc
public class SpringConfig extends WebMvcConfigurerAdapter {


    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        final ObjectMapper objectMapper = new ObjectMapper();
       // objectMapper.setSerializationInclusion(Inclusion.NON_EMPTY);
        objectMapper.setSerializationInclusion(Include.NON_EMPTY);    
        converter.setObjectMapper(objectMapper);
        converters.add(converter);
        super.configureMessageConverters(converters);
    }
}

How to remove the Empty Objects from the JSON Reponse Object.

Answer 1

I had similar requirement, but though I use CXF framework on spring boot, there spring boot was creating ObjectMapper which was overriding configuration. Hence I was manually create ObjectMapper as shown below.

@Bean(name = "objectMapper")
    public ObjectMapper getObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(
                SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED, false);
        mapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY,
                true);
        mapper.setSerializationInclusion(Include.NON_NULL);
        return mapper;
    }

Answer 2

You can create your custom serializer where you can add a condition on serialization of the object.

Model

@JsonSerialize(using = IgnoreEmptyPersonSerializer.class)
public class Person {

    private String name;
    private String address;

    public Person(String name, String address){
        this.name = name;
        this.address = address;
    }
    ...
    //setters and getters
    ...
}

Custom Serializer

public class IgnoreEmptyPersonSerializer extends JsonSerializer<Person> {

    @Override
    public void serialize(Person value, JsonGenerator jgen, SerializerProvider provider)
            throws IOException, JsonProcessingException {

        String name = value.getName();
        String address = value.getAddress();

        //Dont serialize it if it is empty
        if((name == null || name.trim().equals("")) &&
                (address == null || address.trim().equals(""))){
            return;
        }

        jgen.writeStartObject();
        jgen.writeFieldName("name");
        jgen.writeString(value.getName());
        jgen.writeFieldName("address");
        jgen.writeString(value.getAddress());
        jgen.writeEndObject();

    }
}