Ignoring new fields on JSON objects using Jackson

Question

I m using Jackson JSON library to convert some JSON objects to POJO classes on an android application  The problem is  the JSON objects might change and have new fields added while the application is published  but currently it will break even when a simple String field is added  which can safely be ignored    Is there any way to tell Jackson to ignore newly added fields   e g  non-existing on the POJO objects   A global ignore would be great

User · Answer

You can annotate the specific property in your POJO with  JsonIgnore

User · Answer

Starting with Jackson version 2 4 and above there have been some changes  Here is how you do it now   import com fasterxml jackson databind DeserializationFeature  import com fasterxml jackson databind ObjectMapper                                                                                 ObjectMapper mapper   new ObjectMapper           to prevent exception when encountering unknown property   mapper disable DeserializationFeature FAIL ON UNKNOWN PROPERTIES        Note  The  annotation based solution remains the same so if you like to use that see the other answers    For more information see the 10 minutes Configuration tutorial at  https   github com FasterXML jackson-databind

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I m using jackson-xxx 2 8 5 Maven Dependency like    lt dependencies gt       lt  -- https   mvnrepository com artifact com fasterxml jackson core jackson-core -- gt       lt dependency gt           lt groupId gt com fasterxml jackson core lt  groupId gt           lt artifactId gt jackson-core lt  artifactId gt           lt version gt 2 8 5 lt  version gt       lt  dependency gt        lt  -- https   mvnrepository com artifact com fasterxml jackson core jackson-annotations -- gt       lt dependency gt           lt groupId gt com fasterxml jackson core lt  groupId gt           lt artifactId gt jackson-annotations lt  artifactId gt           lt version gt 2 8 5 lt  version gt       lt  dependency gt        lt  -- https   mvnrepository com artifact com fasterxml jackson core jackson-databind -- gt       lt dependency gt           lt groupId gt com fasterxml jackson core lt  groupId gt           lt artifactId gt jackson-databind lt  artifactId gt           lt version gt 2 8 5 lt  version gt       lt  dependency gt    lt  dependencies gt    First If you want ignore unknown properties globally you can config ObjectMapper  Like below   ObjectMapper objectMapper   new ObjectMapper     objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false     If you want ignore some class you can add annotation  JsonIgnoreProperties ignoreUnknown   true  on your class like    JsonIgnoreProperties ignoreUnknown   true  public class E1        private String t1       public String getT1             return t1             public void setT1 String t1            this t1   t1

User · Answer

JsonIgnoreProperties ignoreUnknown   true   worked well for me  I have a java application which runs on tomcat with jdk 1 7

User · Answer

it can be achieved 2 ways    Mark the POJO to ignore unknown properties   JsonIgnoreProperties ignoreUnknown   true   Configure ObjectMapper that serializes De-serializes the POJO json as below   ObjectMapper mapper  new ObjectMapper                   for Jackson version 1 X         mapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false      for Jackson version 2 X mapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false

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If using a pojo class based on JSON response  If chances are there that json changes frequently declare at pojo class level    JsonIgnoreProperties ignoreUnknown   true    and at the objectMapper add this if you are converting   objectMapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false     So that code will not break

User · Answer

In addition to 2 mechanisms already mentioned  there is also global feature that can be used to suppress all failures caused by unknown  unmapped  properties      jackson 1 9 and before objectMapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false      or jackson 2 0 objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false     This is the default used in absence of annotations  and can be convenient fallback

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As stated above the annotations only works if this is specified in the parent POJO class and not the class where the conversion from JSON to Java Object is taking place   The other alternative without touching the parent class and causing disruptions is to implement your own mapper config only for the mapper methods you need for this   Also the package of the Deserialization feature has been moved  DeserializationConfig FAIL ON UNKNOWN PROPERTIES to DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  import org codehaus jackson map DeserializationConfig      objectMapper configure DeserializationConfig Feature FAIL ON UNKNOWN PROPERTIES  false

User · Answer

Make sure that you place the  JsonIgnoreProperties ignoreUnknown   true  annotation to the parent POJO class which you want to populate as a result of parsing the JSON response and not the class where the conversion from JSON to Java Object is taking place

User · Answer

For whom are using Spring Boot  you can configure the default behaviour of Jackson by using the Jackson2ObjectMapperBuilder   For example     Bean public Jackson2ObjectMapperBuilder configureObjectMapper         Jackson2ObjectMapperBuilder oMapper   new Jackson2ObjectMapperBuilder        oMapper failOnUnknownProperties false       return oMapper      Then you can autowire the ObjectMapper everywhere you need it  by default  this object mapper will also be used for http content conversion

User · Answer

Jackson provides an annotation that can be used on class level  JsonIgnoreProperties     Add the following to the top of your class  not to individual methods     JsonIgnoreProperties ignoreUnknown   true  public class Foo               Depending on the jackson version you are using you would have to use a different import in the current version it is   import com fasterxml jackson annotation JsonIgnoreProperties    in older versions it has been   import org codehaus jackson annotate JsonIgnoreProperties

User · Answer

Up to date and complete answer with Jackson 2    Using Annotation  import com fasterxml jackson annotation JsonIgnoreProperties    JsonIgnoreProperties ignoreUnknown   true  public class MyMappingClass        See JsonIgnoreProperties on Jackson online documentation    Using Configuration  Less intrusive than annotation   import com fasterxml jackson databind DeserializationFeature  import com fasterxml jackson databind ObjectMapper  import com fasterxml jackson databind ObjectReader   ObjectMapper objectMapper   new ObjectMapper    objectMapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false    ObjectReader objectReader   objectMapper reader MyMappingClass class   MyMappingClass myMappingClass   objectReader readValue json     See FAIL ON UNKNOWN PROPERTIES on Jackson online documentation

[java] Ignoring new fields on JSON objects using Jackson

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