How to Call Default Deserializer from a Custom Deserializer in Jackson
When customizing deserialization in Jackson, you may encounter the need to access the default deserializer to populate your object. This can be achieved by employing a BeanDeserializerModifier and registering it via a SimpleModule.
Here's an example implementation:
public class UserEventDeserializer extends StdDeserializer<User> implements ResolvableDeserializer { private final JsonDeserializer<?> defaultDeserializer; public UserEventDeserializer(JsonDeserializer<?> defaultDeserializer) { super(User.class); this.defaultDeserializer = defaultDeserializer; } @Override public User deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException { User deserializedUser = (User) defaultDeserializer.deserialize(jp, ctxt); // Special logic return deserializedUser; } @Override public void resolve(DeserializationContext ctxt) throws JsonMappingException { ((ResolvableDeserializer) defaultDeserializer).resolve(ctxt); } public static void main(String[] args) throws Exception { SimpleModule module = new SimpleModule(); module.setDeserializerModifier(new BeanDeserializerModifier() { @Override public JsonDeserializer<?> modifyDeserializer(DeserializationConfig config, BeanDescription beanDesc, JsonDeserializer<?> deserializer) { if (beanDesc.getBeanClass() == User.class) return new UserEventDeserializer(deserializer); return deserializer; } }); ObjectMapper mapper = new ObjectMapper(); mapper.registerModule(module); User user = mapper.readValue(new File("test.json"), User.class); } }
By registering this modifier, you can access the default deserializer and pre-populate your object within your custom deserializer without causing an exception.
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