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();
}

I wrote a post about [How to Write a Custom Serializer with Jackson](https://spin.atomicobject.com/2016/07/01/custom-serializer-jackson/?utm_source=stack-overflow-ao&utm_medium=referral&utm_campaign=custom-serializer-jackson) that may be helpful to some. — Sam Berry, Jul 01 '16 at 15:04

score 440 · Accepted Answer · edited Mar 19 '19 at 08:43

440

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().

edited Mar 19 '19 at 08:43

voliveira89

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answered Dec 06 '11 at 05:53

Programmer Bruce

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This worked for me. As of Jackson 2.0, ObjectMapper#setVisibility takes a PropertyAccessor as the first argument. The equivalent oneliner is `myObjectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);` – Dan Robinson Mar 28 '13 at 05:26
@DanRobinson I used same. But actually I am generating yaml file. so for the JSONString as : `{"term":{"call_failed":"true"}}` it is generating yaml structure as: `filter: map: term: map: call_failed: "true"` Why it is generating `map` keyword? How can I remove it ? – Manish Kumar Aug 03 '16 at 13:32
8

I probably spent 8 hours with this error, not realizing that my getter method did not have "public" on it..so stupid – Mike Kellogg Nov 23 '16 at 15:26
1

I am getting this error while converting ClientResponse to string using object mapper – VedantK May 24 '17 at 14:03
6

You can also add the annotation `@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY)` above your class – veben Oct 10 '19 at 07:06

score 141 · Answer 2 · edited Jul 21 '20 at 08:49

141

Add a

getter

and a

setter

and the problem is solved.

edited Jul 21 '20 at 08:49

Andreas is moving to Codidact

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answered Oct 12 '15 at 16:36

Günay Gültekin

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Tried many different things, and the solution is as simple as this....and it says it quite clearly: "no properties discovered to create". – aks Sep 30 '18 at 23:41
3

@PhilipRego He means he added a getter and setter for the field. – Paul Apr 25 '19 at 15:59
2

I use lombok library, so I just add anotation Getter and Setter. And everything was fine. Thanks. – Rahmat Hidayat Sep 03 '19 at 07:13
2

yeah, getters and setters are used for Jackson serialization./deserialization – Ikhiloya Imokhai Dec 28 '19 at 15:49
3

adding Getters alone solved the issue for me, no need to add setters – ddc Feb 26 '21 at 18:08
Just add Getters and the problem will be solved.setters are not compulsory – Kashinath Jun 14 '23 at 10:42

score 92 · Answer 3 · edited Jul 22 '17 at 17:24

92

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.

edited Jul 22 '17 at 17:24

Nathan

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answered Dec 03 '11 at 11:29

Chris

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Please note this answer is incorrect -- the field does not *need* to be public or have a getter and setter. In another answer to this question, I provided an alternative configuration that does not require changes to the original data structure to be (de)serialized. – Programmer Bruce Feb 28 '13 at 03:45
10

The answer is useful, even if not 100% precisely correct. I'd forgotten to put 'public' on my vars, and this pointed that out. Thanks! – ChrisPhoenix Apr 17 '15 at 03:08

score 39 · Answer 4 · edited Jul 22 '17 at 17:22

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

score 10 · Answer 5 · answered Jan 31 '18 at 08:44

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)

score 9 · Answer 6 · answered Oct 12 '21 at 09:26

9

Jackson uses getters and setters serialization./deserialization. So add getter and setter in your model class.

answered Oct 12 '21 at 09:26

Nakesh

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score 8 · Answer 7 · answered May 07 '13 at 13:25

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

score 8 · Answer 8 · answered Jan 16 '15 at 02:57

8

If you can edit the class containing that object, I usually just add the annotation

import com.fasterxml.jackson.annotation.JsonIgnore;

@JsonIgnore 
NonSerializeableClass obj;

answered Jan 16 '15 at 02:57

ZiglioUK

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This error fires also when your class has a method with name starting with get... For example NonSerializableClass getMyNonSerializableObject(). Jackson tries to serialise it and fails. To resolve this problem just add @JsonIgnore or rename the method. – Alexey Podlasov Nov 16 '15 at 18:39
1

Used the older version: `org.codehaus.jackson.annotate.JsonIgnore` – AlikElzin-kilaka Jan 06 '16 at 09:47

score 7 · Answer 9 · answered Sep 08 '18 at 09:58

7

SpringBoot2.0 ，I resolve it by follow code:

@Bean public ObjectMapper objectMapper() {
 return new ObjectMapper().disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);}

answered Sep 08 '18 at 09:58

Janus

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you should keep your model has getter and setter methods. – Janus Sep 08 '18 at 09:59
2

Welcome to SO! Thanks for contributing. Please add an explanation to your answer, so it's clear what the code does, why it works and how it answers OPs question. – Max Vollmer Sep 08 '18 at 10:07
This helped me! But in my opinion, you should inject the ObjectMapper of the context and configure it afterward rather than creating a new one. – RoBeaToZ Aug 28 '19 at 09:31

score 5 · Answer 10 · answered Jul 06 '18 at 11:07

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.

score 4 · Answer 11 · answered May 03 '17 at 14:56

4

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"})

answered May 03 '17 at 14:56

N. berouain

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This solved my problem. Can you tell me what this exactly does? – scarface Dec 02 '17 at 14:07
None of the other solutions worked for me. This one solved the problem. Can anyone explain in detail what the above statement does? – Aswin Prasad Jul 28 '20 at 08:07

score 3 · Answer 12 · edited Jul 22 '17 at 17:23

3

For Oracle Java applications, add this after the ObjectMapper instantiation:

mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);

edited Jul 22 '17 at 17:23

Nathan

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answered Nov 24 '16 at 22:06

LEMUEL ADANE

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score 3 · Answer 13 · edited Aug 08 '18 at 08:35

3

Here are the three options:

Data/class that's been accessed needs to be public
If not public, add getters & setters
Or add @JsonIgnore("context")

edited Aug 08 '18 at 08:35

anothernode

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answered Aug 08 '18 at 08:07

Santhosh Kumar

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score 2 · Answer 14 · edited Jul 22 '17 at 17:23

2

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!

edited Jul 22 '17 at 17:23

Nathan

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answered Feb 22 '16 at 09:55

Sanchit Singhania

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raveendra_bikkina · Answer 15 · 2019-10-05T05:59:07.037

2

Please use this at class level for the bean:

@JsonIgnoreProperties(value={"hibernateLazyInitializer","handler","fieldHandler"})

edited Oct 05 '19 at 05:59

answered Oct 05 '19 at 05:52

raveendra_bikkina

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score 2 · Answer 16 · answered Mar 19 '20 at 02:42

2

I just had only getters , after adding setters too , problems resolved.

answered Mar 19 '20 at 02:42

Vanita Dhotre

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score 2 · Answer 17 · answered Feb 06 '23 at 03:37

2

Adding a getter/setter solved this problem for me. either manually add getter/setter or use Lombok annotations @Getter/@Setter/@Data for the same.

answered Feb 06 '23 at 03:37

Sumit Jadiya

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score 2 · Answer 18 · edited Jun 28 '23 at 06:10

2

Add this in your application properties file

spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false

edited Jun 28 '23 at 06:10

Codemaker2015

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answered Jun 25 '23 at 13:55

hiten

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score 1 · Answer 19 · edited Feb 06 '20 at 13:35

1

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 ;   } 
}

edited Feb 06 '20 at 13:35

David

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answered Feb 06 '20 at 11:50

Satya Prakash

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score 0 · Answer 20 · answered Oct 31 '17 at 16:23

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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.

answered Oct 31 '17 at 16:23

yellow

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score 0 · Answer 21 · answered Apr 08 '20 at 08:44

0

in spring boot 2.2.5

after adding getter and setter

i added @JsonIgnore on top of the field.

answered Apr 08 '20 at 08:44

saba

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This will ignore the property. If the property to be read, then we should add getters and setters – RenceAbi Jun 28 '20 at 08:13

score 0 · Answer 22 · answered Dec 22 '20 at 14:12

0

If you use Lomdok libraray (https://projectlombok.org/) then add @Data (https://projectlombok.org/features/Data) annotation to your data object class.

answered Dec 22 '20 at 14:12

Andriy Kryvtsun

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j.xavier.atero · Answer 23 · 2022-08-26T08:36:52.730

0

For me, the problem was the annotation @RestResource(exported = false) from the import org.springframework.data.rest.core.annotation.RestResource. Which I forgot to remove.

Also, I got the same error when I forgot to add the class annotation @XmlRootElement from the import javax.xml.bind.annotation.XmlRootElement.

edited Aug 26 '22 at 08:36

answered Aug 26 '22 at 08:23

j.xavier.atero

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score 0 · Answer 24 · answered Jan 06 '23 at 20:52

0

I solved with @Getter from lombok

answered Jan 06 '23 at 20:52

Sham Fiorin

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Serializing with Jackson (JSON) - getting "No serializer found"?

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