Serialize @JsonIgnore-d field

Question

I have class with @JsonIgnore-d field:

public class MyClass {
    ...
    @JsonIgnore
    private SomeType myfield;
    ...
    // getters & setters
}

Is it possible to configure ObjectWriter so that it includes myfield during serialization even though being ingored? Rationale: MyClass is serialized in many places and only in single specific one I want to have myfield.

Answer 1

It is possible to configure ObjectMapper to disable a JsonIgnore function. Following are some possible solution you can try with:

1. Disable JsonIgnore function for a particular annotated field.

You can create a custom JsonIgnore annotation and a custom JacksonAnnotationIntrospector to remove the annotation from mapper context. Following are the ideas:

Annotate @MyJsonIgnore to the fields that should be ignored while serialization:

@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY)
public class MyClass {

    @MyJsonIgnore
    private SomeType myField;

}

@MyJsonIgnore is a simple custom annotation that wrap @JsonIgnore:

@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotationsInside
@JsonIgnore
public @interface MyJsonIgnore {
}

A custom JacksonAnnotationIntrospector is implemented to remove @MyJsonIgnore from mapper context:

public class DisablingMyJsonIgnoreIntrospector extends JacksonAnnotationIntrospector {

@Override
public boolean isAnnotationBundle(final Annotation ann) {
    if (ann.annotationType().equals(MyJsonIgnore.class)) {
        return false;
    } else {
        return super.isAnnotationBundle(ann);
    }
}

After that, you can set the introspector on a ObjectMapper during configuration:

ObjectMapper mapper = new ObjectMapper();
mapper.setAnnotationIntrospector(new DisablingMyJsonIgnoreIntrospector());

It results that the fields annotated with @MyJsonIgnore can be marshaled properly.

2. Disable JsonIgnore function for the mapper

Your can create a custom JacksonAnnotationIntrospector and override hasIgnoreMarker method to always return false:

public static class DisablingJsonIgnoreIntrospector extends JacksonAnnotationIntrospector {

    @Override
    public boolean hasIgnoreMarker(final AnnotatedMember m) {
        return false;
    }

}

hasIgnoreMarker is to check whether there is annotation to ignore json property. Return false will disable the JsonIngore function.

3. Disable all annotations and specify what kinds of properties are auto-detected for a given ObjectMapper:

final ObjectMapper mapper = new ObjectMapper();
mapper.disable(MapperFeature.USE_ANNOTATIONS);
mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);

This simply disable all annotations.

Hope this can help.