Jax-RS app with Payara server dosen't serialize Color via custom Serializer

Question

I'm developing JAX-RS based application and Payara server. I want to serialize build in java Color class to String format: color = "RcolorValu, GColorValue, BColor value". For example in form "255,255,255". That's why I've written custom serializer:

package org.example;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.awt.*;
import java.io.IOException;
import java.util.logging.Logger;
public class ColorSerializer extends JsonSerializer<Color> {
    private static final Logger logger = Logger.getLogger(ColorSerializer.class.getName());

    @Override
    public void serialize(Color color, JsonGenerator generator, SerializerProvider serializers) throws IOException {
        logger.info("Serializing color init ");
        if (color == null) {
            generator.writeNull();
        } else {
            String colorString = color.getRed() + "," + color.getGreen() + "," + color.getBlue();
            logger.info("Serializing color: " + colorString); // Add logging
            generator.writeString(colorString);
        }
    }
}

I also've registered it in ObjectMapperProvider like below:

package org.example;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import jakarta.enterprise.context.ApplicationScoped;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.ext.ContextResolver;
import jakarta.ws.rs.ext.Provider;

import java.awt.*;

@Provider
public class ObjectMapperProvider implements ContextResolver<ObjectMapper> {

    private final ObjectMapper objectMapper;

    public ObjectMapperProvider() {
        // Register the JavaTimeModule for date/time serialization
        objectMapper = new ObjectMapper();
        objectMapper.registerModule(new JavaTimeModule());
        objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

        // Register the custom ColorSerializer
        SimpleModule module = new SimpleModule();
        module.addSerializer(Color.class, new ColorSerializer());
        objectMapper.registerModule(module);
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return objectMapper;
    }
}

My Employee entity class with favoriteColor property and annotation @JsonSerialize(using = ColorSerializer.class) which should cause serialization is in form like below:

package org.example;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import jakarta.json.bind.annotation.JsonbDateFormat;
import jakarta.persistence.*;

import java.awt.*;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table(name = "Employee")
public class Employee implements Serializable {

    @Id
    @Column(name = "EMPLOYEE_ID")
    private Long id;

    @Column(name = "FIRST_NAME")
    private String firstName;

    @Column(name = "LAST_NAME")
    private String lastName;


    public Date getHireDate() {
        return hireDate;
    }

    public void setHireDate(Date hireDate) {
        this.hireDate = hireDate;
    }

    @Column(name = "HIRE_DATE")
    @Temporal(TemporalType.DATE)
    @JsonbDateFormat("yyyy-MM-dd")
    private Date hireDate;

    @Column(name = "GENDER")
    @Enumerated(EnumType.STRING)
    private Gender gender;

    public Color getFavoriteColor() {
        return favoriteColor;
    }

    public void setFavoriteColor(Color favoriteColor) {
        this.favoriteColor = favoriteColor;
    }

    @Column(name = "FAVORITE_COLOR")
    @Convert(converter = ColorConverter.class)
    @JsonSerialize(using = ColorSerializer.class)
    private Color favoriteColor;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public Gender getGender() {
        return gender;
    }

    public void setGender(Gender gender) {
        this.gender = gender;
    }
}

And my EmployeeResource with list of employee endpoint which should return list of Employees:

package org.example;

import jakarta.enterprise.context.RequestScoped;
import jakarta.inject.Inject;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

import java.util.List;
import java.util.logging.Logger;

@Path("/employee")
@RequestScoped
public class EmployeeResource {

    @Inject
    private EmployeeService employeeService;

    private static final Logger logger = Logger.getLogger(EmployeeService.class.getName());


    @GET
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/")
    public List<Employee> getEmployees() {
        logger.info("Retrieving all employees");
        return employeeService.getAllEmployees();
    }   
}

Besides that I configured Converter which works. I figured out it from logs but Serializer dosen't :

package org.example;

import jakarta.persistence.AttributeConverter;
import jakarta.persistence.Converter;

import java.awt.*;
import java.util.logging.Logger;

@Converter(autoApply = true)
public class ColorConverter implements AttributeConverter<Color, String> {

    private static final Logger logger = Logger.getLogger(ColorSerializer.class.getName());


    @Override
    public String convertToDatabaseColumn(Color attribute) {
        logger.info("converter color color: " + attribute.toString()); // Add logging
        return attribute.getRed() +
                "," +
                attribute.getGreen() +
                "," +
                attribute.getBlue();
    }

    @Override
    public Color convertToEntityAttribute(String dbData) {
        if (dbData == null || dbData.isBlank()) {
            return null;
        }
        String[] parts = dbData.split(",");
        Color color = new Color(Integer.parseInt(parts[0]), Integer.parseInt(parts[1]), Integer.parseInt(parts[2]));
        logger.info("Converting DB data to color: " + color.toString()); // Add logging
        return color;
    }
}

In any case I receive every time json response like:

Example data in database:

I don't know how to leverage using my Custom Serializer instead of build in.

Answer 1

You're mixing JSON-Binding and Jackson annotations in the same application. JSON-Binding annotations are in packages that start with jakarta.json.bind.annotation, e.g. the JsonbDateFormat annotation in your code. Jackson annotations are in packages that start with com.fasterxml.jackson, e.g. JsonSerialize. You can only use one or the other, not both. Payara doesn't support Jackson annotations out of the box. If you enable Jackson, then JSON-Binding annotations will be ignored, because Jackson doesn't support JSON-Binding.

Find out whether you use the standard JSON-Binding or you enabled Jackson (as described here). If you didn't enable Jackson, then the JsonSerialize annotation and all the Jackson configuration in the ObjectMapperProvider are ignored. Then you should rather use JsonbSerializer in JSON-Binding instead. It's documented in the Jakarta EE tutorial here: https://jakarta.ee/learn/docs/jakartaee-tutorial/current/web/jsonb/jsonb.html#_using_customizations

Or you should enable Jackson and replace the JsonbDateFormat annotation and other JSON-B annotations with something equivalent that Jackson supports.

Your ColorConverter class is a converter for persistent entities. It's used when the data is stored to the database. It's ignored when the JSON is build for a REST response.