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

java

serialization

jackson

deserialization

byAnton Shumikhin·Dec 7, 2024

With Jackson, you can bypass the property serialization issue using a mixin with an @JsonIgnore annotation. Here's how:

@JsonIgnoreProperties({"propertyToIgnore"})
abstract class MyMixin {}

ObjectMapper mapper = new ObjectMapper();
mapper.addMixIn(Target.class, MyMixin.class);

By using this configuration, Jackson will conveniently ignore propertyToIgnore during the serialization process of the Target class.

Customizing serialization without changing source code

If you are in a situation where you need to exclude certain elements from serialization but don't have control over the source code, don't worry! Jackson has got you covered. Let's look at a few possibilities:

Ignore unknown properties: You can instruct the ObjectMapper to disregard unknown properties like this:

objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
// Keep calm and ignore unknown properties.

Additionally, you can use the @JsonIgnoreProperties annotation to ignore unpredicted properties at class level:
```
@JsonIgnoreProperties(ignoreUnknown = true)
// Avoid surprises with unexpected properties.
```

Employing mixins and filters to tackle serialization

Mixin to rule them all

Jackson lets you define a rule that applies to multiple classes. Enter setMixInResolver with MixInResolver implementation. This powerful approach allows you to define the logic for finding mix-in classes for target classes on the fly.

@JsonIgnoreProperties({"unwantedGlobalProperty"})
abstract class GlobalPropertyIgnoreMixIn {}

mapper.setMixInResolver(new SimpleMixInResolver(null) {
    @Override
    public Class<?> findMixInClassFor(Class<?> cls) {
        // One mixin to rule them all 💍
        return GlobalPropertyIgnoreMixIn.class;
    }
});

Dynamic filtering using `JsonFilter`

Using a JsonFilter can bring even more flexibility to your filtering:

Define your filter:

@JsonFilter("yourFilter")
abstract class YourBean {}

Create your filter rule:

SimpleFilterProvider filters = new SimpleFilterProvider().addFilter("yourFilter",
    SimpleBeanPropertyFilter.serializeAllExcept("propertyToIgnore"));

Apply the filters using an ObjectWriter:

ObjectWriter writer = mapper.writer(filters);

Guide to custom deserialization

Feel free to use @JsonCreator and @JsonProperty annotations to control deserialization:

class CustomDeserialized {
    private String property1;

    @JsonCreator
    public CustomDeserialized(@JsonProperty("property1") String prop1) {
        // handle with care 🎁
        this.property1 = prop1;
    }
}