Serializing with Jackson JSON - getting No serializer found

Question

I get the an exception when trying to serialize a very simple object using Jackson  The error      org codehaus jackson map JsonMappingException  No serializer found for   class MyPackage TestA and no properties   discovered to create BeanSerializer  to avoid exception  disable   SerializationConfig Feature FAIL ON EMPTY BEANS      Below is the simple class and code to serialize    Can anyone tell my why I get this error   public class TestA       String SomeString    asd      TestA testA   new TestA    ObjectMapper om   new ObjectMapper    try       String testAString   om writeValueAsString testA      error here       TestA newTestA   om readValue testAString  TestA class     catch  JsonGenerationException e           TODO Auto-generated catch block     e printStackTrace      catch  JsonMappingException e           TODO Auto-generated catch block     e printStackTrace      catch  IOException e           TODO Auto-generated catch block     e printStackTrace

User · Answer

Here are the three options    Data class that s been accessed needs to be public If not public  add getters  amp  setters Or add  JsonIgnore  context

User · Answer

I just had only getters   after adding setters too   problems resolved

User · Answer

As already described  the default configuration of an ObjectMapper instance is to only access properties that are public fields or have public getters setters   An alternative to changing the class definition to make a field public or to provide a public getter setter is to specify  to the underlying VisibilityChecker  a different property visibility rule   Jackson 1 9 provides the ObjectMapper setVisibility   convenience method for doing so   For the example in the original question  I d likely configure this as  myObjectMapper setVisibility JsonMethod FIELD  Visibility ANY     For Jackson  2 0   myObjectMapper setVisibility PropertyAccessor FIELD  Visibility ANY     For more information and details on related configuration options  I recommend reviewing the JavaDocs on ObjectMapper setVisibility

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I found at least three ways of doing this    Add public getters on your entity that you try to serialize  Add an annotation at the top of the entity  if you don t want public getters  This will change the default for Jackson from Visbility DEFAULT to  JsonAutoDetect fieldVisibility   JsonAutoDetect Visibility ANY  where any access modifiers are accepted  Change your ObjectMapper globally by setting objectMapperInstance setVisibility JsonMethod FIELD  Visibility ANY    This should be avoided if you don t need this functionality globally    Choose based on your needs

User · Answer

For Jackson to serialize that class  the SomeString field needs to either be public  right now it s package level isolation  or you need to define getter and setter methods for it

User · Answer

This error is also thrown if you forget to add the  build   method onto your return status   return Response status Status OK              fails return Response status Status OK  build       works   I got the following error without build   method   org codehaus jackson map JsonMappingException  No serializer found for class com sun jersey core spi factory ResponseBuilderImpl

User · Answer

If you can edit the class containing that object  I usually just add the annotation  import com fasterxml jackson annotation JsonIgnore    JsonIgnore  NonSerializeableClass obj

User · Answer

SpringBoot2 0  I resolve it by follow code    Bean public ObjectMapper objectMapper      return new ObjectMapper   disable SerializationFeature FAIL ON EMPTY BEANS

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For Oracle Java applications  add this after the ObjectMapper instantiation       mapper setVisibility PropertyAccessor FIELD  JsonAutoDetect Visibility ANY

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I had the same problem for a child class where I had control  object mapper was in a common module and was inaccessible  I solved it by adding this annotation for my child class whose object was to be serialized    JsonAutoDetect fieldVisibility   JsonAutoDetect Visibility ANY

User · Answer

Though I added getters and setters I was getting the same error  Later I found a bug  that is by Sonar s advice I cgahnged the getters and setters as protected which was causing the issue  Once I fixed that it worked as exppected

User · Answer

If you use Lomdok libraray  https   projectlombok org   then add  Data  https   projectlombok org features Data  annotation to your data object class

User · Answer

Add a  getter  and a  setter  and the problem is solved

User · Answer

in spring boot 2 2 5  after adding getter and setter   i added  JsonIgnore on top of the field

User · Answer

The problem in my case was Jackson was trying to serialize an empty object with no attributes nor methods   As suggested in the exception I added the following line to avoid failure on empty beans   For Jackson 1 9  myObjectMapper configure SerializationConfig Feature FAIL ON EMPTY BEANS  false     For Jackson 2 X  myObjectMapper configure SerializationFeature FAIL ON EMPTY BEANS  false     You can find a simple example on jackson disable fail on empty beans

User · Answer

I had a similar problem with lazy loading via the hibernate proxy object  Got around it by annotating the class having lazy loaded private properties with    JsonIgnoreProperties   hibernateLazyInitializer    handler

User · Answer

The problem may be because you have declared variable as private  If you change it to public  it works   Better option is to use getter and setter methods for it   This will solve the issue

User · Answer

Please use this at class level for the bean    JsonIgnoreProperties value   hibernateLazyInitializer   handler   fieldHandler

User · Answer

adding setter and getter will also solve the issue as it fixed for me   For Ex   public class TestA       String SomeString    asd        public String getSomeString             return SomeString              public void setSomeString  String SS            SomeString   SS

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