Serializing Optional not enabled by default since 2.16.0 #4499
Description
Search before asking
- I searched in the issues and found nothing similar.
Describe the bug
in version 2.15.4 the following code below succeeded
giving the output
{"test":{"empty":false,"present":true}}
{"test":{"empty":false,"present":true}}
(Obviously this value doesn't make sense, but it doesn't fail with a hard exception, breaking existing projects)
when using version a higher version e.g. 2.17.0 the following Exception occurs instead (in both cases the jackson-datatype-jdk8.jar of the same version is on the classpath)
Exception in thread "main" com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Java 8 optional type `java.util.Optional` not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jdk8" to enable handling (through reference chain: java.util.ImmutableCollections$Map1["test"])
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77)
at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1330)
at com.fasterxml.jackson.databind.ser.impl.UnsupportedTypeSerializer.serialize(UnsupportedTypeSerializer.java:35)
at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:808)
at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeWithoutTypeInfo(MapSerializer.java:764)
at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:720)
at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:35)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:502)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:341)
at com.fasterxml.jackson.databind.ObjectMapper._writeValueAndClose(ObjectMapper.java:4799)
at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:4040)
at Jackson2_17_Test_ObjectMapper2.main(Jackson2_17_Test_ObjectMapper2.java:24)
I didn't find this default behavior change in the release notes, so I wonder whether this is an intended change.
As a workaround I can register the Jdk8Module manually (commented out in the code above), to produce the same results as in 2.15.4
Version Information
2.17.0
Reproduction
Run the example using the maven dependencies
- com.fasterxml.jackson.core:jackson-databind:2.15.4
- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:2.15.4
after switching to 2.16.0, 2.16.1, 2.17.0 the same code below fails
- com.fasterxml.jackson.core:jackson-databind:2.17.0
- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:2.17.0
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import java.util.Map;
import java.util.Optional;
public class Jackson2_17_Test_Optional {
public static void main(String[] args) throws JsonProcessingException {
Map<String, Optional<String>> object = Map.of(
"test", Optional.of("optional value"));
JsonMapper jsonMapper = JsonMapper.builder()
// .addModule(new Jdk8Module()) // workaround, register jdk8 module manually
.build();
String value = jsonMapper.writeValueAsString(object);
System.out.println(value);
ObjectMapper objectMapper = new ObjectMapper();
// objectMapper.registerModule(new Jdk8Module()); // workaround, register jdk8 module manually
String value2 = objectMapper.writeValueAsString(object);
System.out.println(value2);
}
}Expected behavior
giving the output as in 2.15.4, not throwing an exception
{"test":{"empty":false,"present":true}}
{"test":{"empty":false,"present":true}}
Additional context
even though we have a manual workaround it's difficult to track and adjust all usages by external libraries.
my apologies in case I missed the related documentation and this is the new expected behavior since 2.16.0