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You can mark it as @JsonIgnore.

@JsonIgnore prevents deserialization as well. For transient - I'll check it out.

With 1.9, you can add @JsonIgnore for getter, @JsonProperty for setter, to make it deserialize but not serialize.

StaxMan's comment should be the answer, shouldn't it? Why is it still a comment then...!..?

transient doesnt seem to work for me, i marked the field "transient" that i donot want it to be serilized/deserialized.

transient
private transient String password;

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@JsonIgnore
public String password;

@JsonIgnore
public String getPassword() {
    return password;
}

@JsonProperty
public void setPassword(String password) {
    this.password = password;
}

Thanks! @JsonIgnore is not necessary on the field, it seems.

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Here is the original example modified to exclude the plain text password, but then annotate a new method that just returns the password field as encrypted text.

class User {
    private String password;

    public void setPassword(String password){...}
    @JsonIgnore
    public String getPassword(){...}

    @JsonProperty("password"}
    public String getEncryptedPassword(){...}
}

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Aside from @JsonIgnore, there are a couple of other possibilities:

  • Use JSON Views to filter out fields conditionally (by default, not used for deserialization; in 2.0 will be available but you can use different view on serialization, deserialization)
@JsonIgnoreProperties

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transient is the solution for me. thanks! it's native to Java and avoids you to add another framework-specific annotation.

You don't have to be locked to jackson if you create your own annotation and have it annotated by JsonIgnore and JacksonAnnotationsInside. That way, if you change serializers, you only have to change your own annotation.

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One should ask why you would want a public getter method for the password. Hibernate, or any other ORM framework, will do with a private getter method. For checking whether the password is correct, you can use

public boolean checkPassword(String password){
  return this.password.equals(anyHashingMethod(password));
}

I actually think this is the best way to think about the solution. It makes more sense to make things you need private and control them from the object itself.

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I am not sure whether it is elegant solution but you can use MixIn feature. You have to create new interface which could look like below:

interface FooMixIn {

    @JsonIgnore
    String getBar();
}
POJO
class Foo {

    private final String bar = null;

    public String getBar() {
        return bar;
    }

    @Override
    public String toString() {
        return bar;
    }
}

Now you have to tell Jackson that you want to ignore this property:

String json = "{\"bar\":\"Value\"}";
System.out.println(json);
ObjectMapper deserializeMapper = new ObjectMapper();
deserializeMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
System.out.println(deserializeMapper.readValue(json, Foo.class));
{"bar":"Value"}
null
deserializeMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
{"bar":"Value"}
Value

If you want to achieve result like you showed you have to create two ObjectMappers and customize them. See below example:

String json = "{\"bar\":\"Value\"}";
ObjectMapper deserializerMapper = new ObjectMapper();
Foo foo = deserializerMapper.readValue(json, Foo.class);
System.out.println("Foo object: " + foo);

ObjectMapper serializerMapper = new ObjectMapper();
serializerMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
serializerMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
System.out.println("JSON: " + serializerMapper.writeValueAsString(foo));

For serialization you have to use one instance and for deserialization you have to use another instance.

Dammit ! +1 because your answer does exactly what you describe and introduced me to Jackson's MixIn but it also made me realized I got the serialization/deserialization process mixed up >< I edited my question, if you know any way of doing such as it answers my real need, I'll gladly accept your answer.

Now I really do not understand what are you trying to do. You want to hide this property in serialization process and at the same time Jackson should be able to deserialize it. Is it true? I want to help, but you have to give me the example how your POJO and JSON look like and you have to show me how you are serializing it (with JSON output) and deserializing it. Good example will be better than 1000 words.

Yes that is exactly what I'm trying to do, sorry my question wasn't clear enough in the first place. I edited it to reflect your example. Let's agree on the fact that the deserialization process means going from a JSON string to a Foo instance and the serialization one from a Foo instance to a JSON string.

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I am not sure whether it is elegant solution but you can use MixIn feature. You have to create new interface which could look like below:

interface FooMixIn {

    @JsonIgnore
    String getBar();
}
POJO
class Foo {

    private final String bar = null;

    public String getBar() {
        return bar;
    }

    @Override
    public String toString() {
        return bar;
    }
}

Now you have to tell Jackson that you want to ignore this property:

String json = "{\"bar\":\"Value\"}";
System.out.println(json);
ObjectMapper deserializeMapper = new ObjectMapper();
deserializeMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
System.out.println(deserializeMapper.readValue(json, Foo.class));
{"bar":"Value"}
null
deserializeMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
{"bar":"Value"}
Value

If you want to achieve result like you showed you have to create two ObjectMappers and customize them. See below example:

String json = "{\"bar\":\"Value\"}";
ObjectMapper deserializerMapper = new ObjectMapper();
Foo foo = deserializerMapper.readValue(json, Foo.class);
System.out.println("Foo object: " + foo);

ObjectMapper serializerMapper = new ObjectMapper();
serializerMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
serializerMapper.addMixInAnnotations(Foo.class, FooMixIn.class);
System.out.println("JSON: " + serializerMapper.writeValueAsString(foo));

For serialization you have to use one instance and for deserialization you have to use another instance.

Dammit ! +1 because your answer does exactly what you describe and introduced me to Jackson's MixIn but it also made me realized I got the serialization/deserialization process mixed up >< I edited my question, if you know any way of doing such as it answers my real need, I'll gladly accept your answer.

Now I really do not understand what are you trying to do. You want to hide this property in serialization process and at the same time Jackson should be able to deserialize it. Is it true? I want to help, but you have to give me the example how your POJO and JSON look like and you have to show me how you are serializing it (with JSON output) and deserializing it. Good example will be better than 1000 words.

Yes that is exactly what I'm trying to do, sorry my question wasn't clear enough in the first place. I edited it to reflect your example. Let's agree on the fact that the deserialization process means going from a JSON string to a Foo instance and the serialization one from a Foo instance to a JSON string.

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To suppress serializing properties with null values, you can configure the ObjectMapper directly, or make use of the @JsonInclude annotation:

mapper.setSerializationInclusion(Include.NON_NULL);
@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.

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)

The API changed a bit with the 2.0 release.

@JsonInclude(Include.NON_NULL) works like a champ when I create a new object with some properties (but some null) and then serialize it to JSON. However, oddly, when I grab an object using a DAO of sorts then serialize that, it doesn't appear to take effect and I get the null properties again. It may not be playing nice with Hibernate or DropWizard, but does any of this ring a bell? Are there times where @JsonInclude would be ignored?

Yeah, I just confirmed that the @JsonInclude notation doesn't work, but this works like a charm: @JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL) (I'm using Jackson 1.9.12 with Spring 3.2.2.)

@MartinAsenov - the answer shows the most recent API; it was changed from the @JsonSerialize syntax to @JsonInclude. The older syntax is deprecated.

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To suppress serializing properties with null values, you can configure the ObjectMapper directly, or make use of the @JsonInclude annotation:

mapper.setSerializationInclusion(Include.NON_NULL);
@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.

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)

The API changed a bit with the 2.0 release.

Yeah, I just confirmed that the @JsonInclude notation doesn't work, but this works like a charm: @JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL) (I'm using Jackson 1.9.12 with Spring 3.2.2.)

@MartinAsenov - the answer shows the most recent API; it was changed from the @JsonSerialize syntax to @JsonInclude. The older syntax is deprecated.

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To suppress serializing properties with null values, you can configure the ObjectMapper directly, or make use of the @JsonInclude annotation:

mapper.setSerializationInclusion(Include.NON_NULL);
@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.

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)

The API changed a bit with the 2.0 release.

Yeah, I just confirmed that the @JsonInclude notation doesn't work, but this works like a charm: @JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL) (I'm using Jackson 1.9.12 with Spring 3.2.2.)

@MartinAsenov - the answer shows the most recent API; it was changed from the @JsonSerialize syntax to @JsonInclude. The older syntax is deprecated.

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With Jackson > 1.9.11 and < 2.x use @JsonSerialize annotation to do that:

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
@JsonSerialize(using = FooSerializer.class, include = JsonSerialize.Inclusion.NON_NULL)

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With Jackson > 1.9.11 and < 2.x use @JsonSerialize annotation to do that:

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
@JsonSerialize(using = FooSerializer.class, include = JsonSerialize.Inclusion.NON_NULL)

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With Jackson > 1.9.11 and < 2.x use @JsonSerialize annotation to do that:

@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
@JsonSerialize(using = FooSerializer.class, include = JsonSerialize.Inclusion.NON_NULL)

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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').

e.g. here only fieldOne will be ommitted from json if it is null. fieldTwo will always be included regardless of if it is null.

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;
}
public class Foo {

    @JsonSerialize(include=JsonSerialize.Inclusion.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.

e.g. 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.NON_NULL)
    private String fieldThree;
}
@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
public class Foo {

    private String fieldOne;

    private String fieldTwo;

    @JsonSerialize(include=JsonSerialize.Inclusion.ALWAYS)
    private String fieldThree;
}
@JsonSerialize(include=JsonSerialize.Inclusion.ALWAYS)
@JsonInclude(JsonInclude.Include.NON_NULL)

java - How to tell Jackson to ignore a field during serialization if i...

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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.NON_NULL)
    private String fieldThree;
}
@JsonSerialize(include=JsonSerialize.Inclusion.ALWAYS)
@JsonInclude(JsonInclude.Include.NON_NULL)

java - How to tell Jackson to ignore a field during serialization if i...

java jackson
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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.NON_NULL)
    private String fieldThree;
}
@JsonSerialize(include=JsonSerialize.Inclusion.ALWAYS)
@JsonInclude(JsonInclude.Include.NON_NULL)

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@JsonInclude(JsonInclude.Include.NON_NULL)

Why/how does this not work with 2.5.1?

@ams , this annotation should wrapper a class

Could you also include the fully qualified name? Jackson has multiple annotations with the same name and a different package, so that is ambiguous.

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@JsonInclude(JsonInclude.Include.NON_NULL)

Why/how does this not work with 2.5.1?

@ams , this annotation should wrapper a class

Could you also include the fully qualified name? Jackson has multiple annotations with the same name and a different package, so that is ambiguous.

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@JsonInclude(JsonInclude.Include.NON_NULL)

Why/how does this not work with 2.5.1?

@ams , this annotation should wrapper a class

Could you also include the fully qualified name? Jackson has multiple annotations with the same name and a different package, so that is ambiguous.

java - How to tell Jackson to ignore a field during serialization if i...

java jackson