How to tell Jackson to ignore a field during serialization if its value is null

Question

How can Jackson be configured to ignore a field value during serialization if that field s value is null    For example   public class SomeClass         what jackson annotation causes jackson to skip over this value if it is null but will        serialize it otherwise     private String someValue

User · Answer

We have lot of answers to this question  This answer may be helpful in some scenarios If you want to ignore the null values you can use the NOT NULL in class level   as below   JsonInclude Include NON NULL  class Foo     String bar      Some times you may need to ignore the empty values such as you may have initialized the arrayList but there is no elements in that list In that time using NOT EMPTY annotation to ignore those empty value fields   JsonInclude Include NON EMPTY  class Foo     String bar

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For Jackson 2 5 use      JsonInclude content Include NON NULL

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To suppress serializing properties with null values using Jackson  2 0  you can configure the ObjectMapper directly  or make use of the  JsonInclude annotation   mapper setSerializationInclusion Include NON NULL     or    JsonInclude Include NON NULL  class Foo     String bar      Alternatively  you could use  JsonInclude in a getter so that the attribute would be shown if the value is not null   A more complete example is available in my answer to How to prevent null values inside a Map and null fields inside a bean from getting serialized through Jackson

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This Will work in Spring boot 2 0 3  and Jackson 2 0   import com fasterxml jackson annotation JsonInclude    JsonInclude JsonInclude Include NON NULL  public class ApiDTO          your class variable and         methods

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Case one    JsonInclude JsonInclude Include NON NULL  private String someString    Case two   JsonInclude JsonInclude Include NON EMPTY  private String someString    If someString is null  it will be ignored on both of cases   If someString is    it just only be ignored on case two    The same for List   null or List size     0

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If you re trying to serialize a list of object and one of them is null you ll end up including the null item in the JSON even with   mapper setSerializationInclusion JsonInclude Include NON NULL     will result in     myObject  null    to get this     myObject     one can do something like   mapper getSerializerProvider   setNullValueSerializer new JsonSerializer lt Object gt               Override         public void serialize Object obj  JsonGenerator jsonGen  SerializerProvider unused                  throws IOException                         IGNORES NULL VALUES                      TIP  If you re using DropWizard you can retrieve the ObjectMapper being used by Jersey using environment getObjectMapper

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Jackson 2 x  use  mapper getSerializationConfig   withSerializationInclusion JsonInclude Include NON NULL

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With Jackson   1 9 11 and  lt  2 x use  JsonSerialize annotation to do that    JsonSerialize include JsonSerialize Inclusion NON NULL

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JsonInclude JsonInclude Include NON NULL   JsonInclude JsonInclude Include NON EMPTY    should work   Include NON EMPTY indicates that property is serialized if its value is not null and not empty  Include NON NULL indicates that property is serialized if its value is not null

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Also  you have to change your approach when using Map myVariable as described in the documentation to eleminate nulls   From documentation  com fasterxml jackson annotation JsonInclude   JacksonAnnotation  Target value  ANNOTATION TYPE  FIELD  METHOD  PARAMETER  TYPE    Retention value RUNTIME  Annotation used to indicate when value of the annotated property  when used for a field  method or constructor parameter   or all properties of the annotated class  is to be serialized  Without annotation property values are always included  but by using this annotation one can specify simple exclusion rules to reduce amount of properties to write out    Note that the main inclusion criteria  one annotated with value  is checked on Java object level  for the annotated type  and NOT on JSON output -- so even with Include NON NULL it is possible that JSON null values are output  if object reference in question is not  null   An example is java util concurrent atomic AtomicReference instance constructed to reference null value  such a value would be serialized as JSON null  and not filtered out   To base inclusion on value of contained value s   you will typically also need to specify content   annotation  for example  specifying only value as Include NON EMPTY for a  link java util Map  would exclude Maps with no values  but would include Maps with  null  values  To exclude Map with only  null  value  you would use both annotations like so  public class Bean       JsonInclude value Include NON EMPTY  content Include NON NULL     public Map lt String String gt  entries     Similarly you could Maps that only contain  empty  elements  or  non-default  values  see Include NON EMPTY and Include NON DEFAULT for more details   In addition to  Map s   content  concept is also supported for referential types  like java util concurrent atomic AtomicReference   Note that  content  is NOT currently  as of Jackson 2 9  supported for arrays or java util Collections  but supported may be added in future versions  Since  2 0

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Just to expand on the other answers - if you need to control the omission of null values on a per-field basis  annotate the field in question  or alternatively annotate the field s  getter     example - here only fieldOne will be ommitted from json if it is null  fieldTwo will always be included regardless of if it is null   public class Foo         JsonInclude JsonInclude Include NON NULL       private String fieldOne       private String fieldTwo      To omit all null values in the class as a default  annotate the class  Per-field getter annotations can still be used to override this default if necessary   example - here fieldOne and fieldTwo will be ommitted from json if they are null  respectively  because this is the default set by the class annotation  fieldThree however will override the default and will always be included  because of the annotation on the field    JsonInclude JsonInclude Include NON NULL  public class Foo        private String fieldOne       private String fieldTwo        JsonInclude JsonInclude Include ALWAYS      private String fieldThree        UPDATE   The above is for Jackson 2  For earlier versions of Jackson you need to use    JsonSerialize include JsonSerialize Inclusion NON NULL     instead of   JsonInclude JsonInclude Include NON NULL    If this update is useful  please upvote ZiglioUK s answer below  it pointed out the newer Jackson 2 annotation long before I updated my answer to use it

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You can use the following mapper configuration   mapper getSerializationConfig   setSerializationInclusion Inclusion NON NULL     Since 2 5 you can user   mapper setSerializationInclusion Include NON NULL

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If in Spring Boot  you can customize the jackson ObjectMapper directly through property files   Example application yml   spring    jackson      default-property-inclusion  non null   only include props if non-null   Possible values are   always non null non absent non default non empty   More  https   docs spring io spring-boot docs current reference html howto-spring-mvc html howto-customize-the-jackson-objectmapper

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Global configuration if you use Spring   Configuration public class JsonConfigurations         Bean     public Jackson2ObjectMapperBuilder objectMapperBuilder             Jackson2ObjectMapperBuilder builder   new Jackson2ObjectMapperBuilder            builder serializationInclusion JsonInclude Include NON NULL           builder serializationInclusion JsonInclude Include NON EMPTY           builder failOnUnknownProperties false           return builder

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In Jackson 2 x  use    JsonInclude JsonInclude Include NON NULL

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This has been troubling me for quite some time and I finally found the issue  The issue was due to a wrong import  Earlier I had been using   com fasterxml jackson databind annotation JsonSerialize   Which had been deprecated  Just replace the import by  import org codehaus jackson map annotate JsonSerialize  import org codehaus jackson map annotate JsonSerialize Inclusion    and use it as    JsonSerialize include Inclusion NON NULL

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in my case     JsonInclude Include NON EMPTY    made it work

User · Answer

If you want to add this rule to all models in Jackson 2 6  use   mapper setSerializationInclusion JsonInclude Include NON NULL

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You can set application properties   spring jackson default-property-inclusion non null   or application yaml   spring    jackson      default-property-inclusion  non null   http   docs spring io spring-boot docs current reference html common-application-properties html

[java] How to tell Jackson to ignore a field during serialization if its value is null?

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