Jackson Annotations not taken into account

[aaron-sr]

Environment Details

• Helidon Version: 2.3.2
• Helidon MP
• JDK version: 11.0.11
• OS: Debian Linux

---

Problem Description

Jackson annotations like @JsonDeserialize are not considered in Resources.

Steps to reproduce

Use following dependency (instead of helidon-media-jsonb)

<dependency>
    <groupId>io.helidon.media</groupId>
    <artifactId>helidon-media-jackson</artifactId>
    <version>2.3.2</version>
</dependency>

Annotate an empty Dto class with a custom deserializer using @JsonDeserialize(using = DtoDeserializer.class).

Test Implementation for DtoSerializer may look like this:

public class DtoDeserializer extends StdDeserializer<Dto> {
	private static final long serialVersionUID = 1L;

	public DtoDeserializer() {
		super(Dto.class);
		throw new RuntimeException();
	}
	
	@Override
	public Dto deserialize(JsonParser parser, DeserializationContext context) {
		throw new RuntimeException();
	}
}

Add a method like this

@POST
@Consumes(MediaType.APPLICATION_JSON)
public void addDto(Dto dto) { ... }

If the custom deserializer is used, an exception must be thrown.

[romain-grecourt]

Not sure if that' the actual problem but io.helidon.media.* is for Helidon SE, however the code snippet you shared is JAXRS based, you need to add a jersey dependency to support Jackson there (i.e org.glassfish.jersey.media:jersey-media-json-jackson)

[aaron-sr]

@romain-grecourt I added your dependency suggestion instead, but no change. Is there any documentation by Helidon/Oracle for this?

From my point of view, it is not possible to change the default json library to jackson (at least for Resources). Is this correct?

[spericas]

@aaron-sr It should work using the Jersey dependency. See https://eclipse-ee4j.github.io/jersey.github.io/documentation/latest/media.html#json.jackson

If it still doesn't work, please provide a copy of your application log.

[romain-grecourt]

The output of mvn dependency:tree would also be useful ; it would indicate if you are using the helidon-microprofile bundle (e.g. if you created your application with the quickstart-mp archetype).

This dependency groups some of the most common Helidon MicroProfile components and it also configures JSON-B out of the box, it adds the following dependencies:

• org.glassfish.jersey.media:jersey-media-json-binding
• jakarta.json.bind:jakarta.json.bind-api
• org.eclipse:yasson

If you add org.glassfish.jersey.media:jersey-media-json-jackson then it becomes dependent on the class-path ordering.

If you are using helidon-microprofile you should remove the dependency to the helidon-microprofile bundle and instead add direct dependencies to the helidon-microprofile-* components you are using.

Or you can manually exclude the 3 JSON-B related dependencies from the bundle.

[romain-grecourt]

The changes required in the pom.xml would look like this:

<dependency>
    <groupId>io.helidon.microprofile.bundles</groupId>
    <artifactId>helidon-microprofile</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-binding</artifactId>
        </exclusion>
        <exclusion>
            <groupId>jakarta.json.bind</groupId>
            <artifactId>jakarta.json.bind-api</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.eclipse</groupId>
            <artifactId>yasson</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
</dependency>