In Jackson, we can use @JsonInclude(JsonInclude.Include.NON_NULL) to ignore the null fields.
P.S Tested with Jackson 2.9.8
1. Jackson default include null fields
1.1 Reviews a POJO, for testing later.
Staff.java
public class Staff {
private String name;
private int age;
private String[] position;
private List<String> skills;
private Map<String, BigDecimal> salary;
1.2 By default, Jackson will include the null fields.
JacksonExample.java
package com.mkyong;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class JacksonExample {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
Staff staff = new Staff("mkyong", 38);
try {
String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(staff);
System.out.println(json);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output
{
"name" : "mkyong",
"age" : 38,
"position" : null,
"skills" : null,
"salary" : null
}
To ignore the null fields, put @JsonInclude on class level or field level.
2. @JsonInclude – Class Level
Staff.java
import com.fasterxml.jackson.annotation.JsonInclude;
// ignore null fields , class level
@JsonInclude(JsonInclude.Include.NON_NULL) // ignore all null fields
public class Staff {
private String name;
private int age;
private String[] position;
private List<String> skills;
private Map<String, BigDecimal> salary;
//...
Output
{
"name" : "mkyong",
"age" : 38
}
3. @JsonInclude – Field Level
Staff.java
import com.fasterxml.jackson.annotation.JsonInclude;
public class Staff {
private String name;
private int age;
@JsonInclude(JsonInclude.Include.NON_NULL) //ignore null field on this property only
private String[] position;
@JsonInclude(JsonInclude.Include.NON_NULL) //ignore null field on this property only
private List<String> skills;
private Map<String, BigDecimal> salary;
Output
{
"name" : "mkyong",
"age" : 38,
"salary" : null
}
4. ObjectMapper.setSerializationInclusion
Alternatively, we also can configure to ignore null fields globally:
JacksonExample2.java
package com.mkyong;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class JacksonExample2 {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
Staff staff = new Staff("mkyong", 38);
try {
// ignore the null fields globally
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(staff);
System.out.println(json);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output
{
"name" : "mkyong",
"age" : 38
}
References
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Thankyou for the post. It saved my day
Hi
not working properly
JsonInclude(jsonInclude.Include.NON_EMPTY)
Thanks for this post. Have you faced any issue when the spring v5.1.3; I changed the WebMvcConfigurationAdapter to WebMvcConfigurationSupport as it is deprecated the null values are showing up. No other implementation is changed.
If I revert back to using WebMvcConfigurationAdapter, it works and null values are not shown in response.
The only thing I have changed is:
public class UmwWebConfig extends WebMvcConfigurationAdapter
to
public class UmwWebConfig extends WebMvcConfigurationSupport
Additional info below is how I add the MappingJackson2HttpMessageConverter (Jackson version 2.9.0)
@Override
public void configureMessageConverters(List<HttpMessageConverter> converters) {
ByteArrayHttpMessageConverter bahHumbug = new ByteArrayHttpMessageConverter();
bahHumbug.setSupportedMediaTypes(Collections.singletonList(MediaType.parseMediaType(“application/pdf”)));
converters.add(bahHumbug);
final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
final ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
objectMapper.getFactory().configure(JsonGenerator.Feature.ESCAPE_NON_ASCII, true);
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
converter.setObjectMapper(objectMapper);
converters.add(converter);
super.configureMessageConverters(converters);
}
Any help is appreciated.