How can I tell jackson to ignore a property for which I don t have control over the source code

Question

Long story short  one of my entities has a GeometryCollection that throws an exception when you call  getBoundary   the why of this is another book  for now let s say this is the way it works     Is there a way I can tell Jackson not to include that specific getter  I know I can use  JacksonIgnore when I do own control the code  But this is not case  jackson ends reaching this point through continuous serialization of the parent objects  I saw a filtering option in jackson documentation  Is that a plausible solution   Thanks

User · Answer

If you want to ALWAYS exclude certain properties for any class  you could use setMixInResolver method        JsonIgnoreProperties   id    index    version        abstract class MixIn              mapper setMixInResolver new ClassIntrospector MixInResolver             Override         public Class lt   gt  findMixInClassFor Class lt   gt  cls                return MixIn class                        Override         public ClassIntrospector MixInResolver copy                 return this

User · Answer

I had a similar issue  but it was related to Hibernate s bi-directional relationships  I wanted to show one side of the relationship and programmatically ignore the other  depending on what view I was dealing with  If you can t do that  you end up with nasty StackOverflowExceptions  For instance  if I had these objects  public class A    Long id    String name    List lt B gt  children     public class B    Long id    A parent      I would want to programmatically ignore the parent field in B if I were looking at A  and ignore the children field in A if I were looking at B   I started off using mixins to do this  but that very quickly becomes horrible  you have so many useless classes laying around that exist solely to format data  I ended up writing my own serializer to handle this in a cleaner way  https   github com monitorjbl json-view    It allows you programmatically specify what fields to ignore   ObjectMapper mapper   new ObjectMapper    SimpleModule module   new SimpleModule    module addSerializer JsonView class  new JsonViewSerializer     mapper registerModule module    List lt A gt  list   getListOfA    String json   mapper writeValueAsString JsonView with list       onClass B class  match            exclude  parent        It also lets you easily specify very simplified views through wildcard matchers   String json   mapper writeValueAsString JsonView with list       onClass A class  match            exclude                include  id    name        In my original case  the need for simple views like this was to show the bare minimum about the parent child  but it also became useful for our role-based security  Less privileged views of objects needed to return less information about the object   All of this comes from the serializer  but I was using Spring MVC in my app  To get it to properly handle these cases  I wrote an integration that you can drop in to existing Spring controller classes    Controller public class JsonController     private JsonResult json   JsonResult instance       Autowired   private TestObjectService service      RequestMapping method   RequestMethod GET  value     bean      ResponseBody   public List lt TestObject gt  getTestObject         List lt TestObject gt  list   service list         return json use JsonView with list           onClass TestObject class  Match match                exclude  int1                include  ignoredDirect              returnValue            Both are available on Maven Central  I hope it helps someone else out there  this is a particularly ugly problem with Jackson that didn t have a good solution for my case

User · Answer

You can use Jackson Mixins  For example   class YourClass     public int ignoreThis     return 0            With this Mixin  abstract class MixIn      JsonIgnore abstract int ignoreThis       we don t need it        With this   objectMapper getSerializationConfig   addMixInAnnotations YourClass class  MixIn class     Edit   Thanks to the comments  with Jackson 2 5   the API has changed and should be called with objectMapper addMixIn Class lt   gt  target  Class lt   gt  mixinSource

User · Answer

One other possibility is  if you want to ignore all unknown properties  you can configure the mapper as follows   mapper configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false

User · Answer

Using Java Class  new ObjectMapper   configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false    Using Annotation   JsonIgnoreProperties ignoreUnknown true

User · Answer

Mix-in annotations work pretty well here as already mentioned  Another possibility beyond per-property  JsonIgnore is to use  JsonIgnoreType if you have a type that should never be included  i e  if all instances of GeometryCollection properties should be ignored   You can then either add it directly  if you control the type   or using mix-in  like    JsonIgnoreType abstract class MixIn        and then register mix-in  either via SerializationConfig  or by using SimpleModule   This can be more convenient if you have lots of classes that all have a single  IgnoredType getContext    accessor or so  which is the case for many frameworks

User · Answer

Annotation based approach is better  But sometimes manual operation is needed  For this purpose you can use without method of ObjectWriter   ObjectMapper mapper     new ObjectMapper   configure DeserializationFeature FAIL ON UNKNOWN PROPERTIES  false  ObjectWriter writer     mapper writer   withoutAttribute  property1   withoutAttribute  property2    String       jsonText   writer writeValueAsString sourceObject

User · Answer

One more good point here is to use  JsonFilter   Some details here http   wiki fasterxml com JacksonFeatureJsonFilter

[java] How can I tell jackson to ignore a property for which I don't have control over the source code?

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