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When using type id with `As.EXTERNAL_PROPERTY` together with @JsonValue inside type the serialiser omits external type id field from result when @JsonValue value is null

See original GitHub issue

Describe the bug

When using type id with As.EXTERNAL_PROPERTY together with @JsonValue inside type the serialiser omits external type id field from result when @JsonValue value is null.

Version information 2.13.3

To Reproduce

package org.example;

import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;
import com.fasterxml.jackson.annotation.JsonValue;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {
  public static interface GenericType {
    String getValue();
    void setValue(String value);

  public static abstract class AbstractGenericType implements GenericType
    protected String value;
    public AbstractGenericType() {}
    public AbstractGenericType(String value) {this.value = value;}
    @Override @JsonValue public String getValue() {return value;}
    @Override @JsonValue public void setValue(String value) {this.value = value;}

  public static class FooType extends AbstractGenericType {
    public FooType() {super();}
    public FooType(String value) {super(value);}
  public static class Container {
    @JsonTypeInfo(use = Id.MINIMAL_CLASS, include = As.EXTERNAL_PROPERTY, property = "type", visible = true)
    @JsonSubTypes(value = {@Type(value = FooType.class)})
    protected GenericType value;

    public GenericType getValue() { return value; }
    public void setValue(GenericType value) { this.value = value; }

  public static void main(String[] args) throws JsonProcessingException {
    var om = new ObjectMapper();

    var container = new Container();

    System.out.println(om.writeValueAsString(container)); // {"value":null}
    // Its fine as container::value == null so external type id field is missing

    container.setValue(new FooType());

    System.out.println(om.writeValueAsString(container)); // {"value":null}
    // Its not fine as container::value != null, external type id field should be set ".Main$FooType" value

    container.setValue(new FooType("foobar"));

    System.out.println(om.writeValueAsString(container)); // {"value":"foobar","type":".Main$FooType"}
    // Now external type id field is present

Expected behavior

Expected that external type id field should be present with type id value when type is not null.

P.S. It would be also great if it was possible to still include external type id field with for e.g. null value when type is null.

Issue Analytics

  • State:open
  • Created a year ago
  • Comments:10 (5 by maintainers)

github_iconTop GitHub Comments

aurimasniekiscommented, Jul 26, 2022

Oh maybe important tip is that @JsonValue is not on generic type, but a property inside the type. In my screenshot it’s TextValueType has get/set value with @JsonValue attribute.

cowtowncodercommented, Jul 31, 2022

@aurimasniekis np at all. I know how limited time can be. Glad that you were able to figure out a work-around at least; that sounds like a good approach to solve your immediate needs fwtw.

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