杰克逊中的多态反序列化将特定字段的值设置为null

Question

Problem statement
Is that the JSON which is to be deserialize into the below given POJO's is setting value of credentialType as null when i send the below JSON through postman

{
"credential": [
    {
        "@type": "mobile",
        "credentialName": "cred-2",
        "email": "s@s.com"
    },
    {
        "@type": "card",
        "credentialNumber": "1"
    }
]

}

Expected outcome
What i want to achieve is that with the above JSON the credential type should be set as either MOBILE for MobileCredentialDto or CARD for CardCredentialDto

@Getter

public class SecureDto {

private  List<CredentialDto> credential;

@JsonCreator
public HandoutDto(@JsonProperty("credential") final List<CredentialDto> credential) {
    this.credential = Collections.unmodifiableList(credential);
}

}

@Getter
public class SecureDto {

    private  List<CredentialDto> credential;

    @JsonCreator
    public HandoutDto(@JsonProperty("credential") final List<CredentialDto> credential) {
        this.credential = Collections.unmodifiableList(credential);
    }
}


@JsonIgnoreProperties(ignoreUnknown = true)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME)
@JsonSubTypes({
        @JsonSubTypes.Type(value = CardCredentialDto.class, name = "card"),
        @JsonSubTypes.Type(value = MobileCredentialDto.class, name = "mobile"),
})
@Getter
@Setter
public class CredentialDto {
    private CredentialType credentialType;

    @JsonCreator
    public CredentialDto(@JsonProperty("credentialType") final String credentialType) {
        this.credentialType = CredentialType.valueOf(credentialType);
    }

    public CredentialDto() {

    }

      public void setCredentialType(final CredentialType credentialType) {
        this.credentialType = CredentialType.MOBILE;
    }
}

@Getter
@Setter
public class MobileCredentialDto extends CredentialDto {
    private String credentialName;
    private String email;

    public MobileCredentialDto(final String credentialId,
                               final String state,
                               final String credentialNumber,
                               final String credentialName,
                               final String email) {
        super(credentialId, state, credentialNumber, CredentialType.MOBILE.name());
        this.credentialName = credentialName;
        this.email = email;
    }

    public MobileCredentialDto() {

    }

    public String getCredentialName() {
        return credentialName;
    }

    public String getEmail() {
        return email;
    }
}


@Getter
@Setter
public class CardCredentialDto extends CredentialDto {

    public CardCredentialDto(final String credentialId,
                             final String state,
                             final String credentialNumber) {
        super(credentialId, state, credentialNumber,CredentialType.CARD.name());
    }

    public CardCredentialDto() {

    }
}

public enum CredentialType {
    MOBILE("MOBILE"),
    CARD("CARD");

    private final String name;

    CredentialType(final String name) {
        this.name = name;
    }
}

Answer 1

I Found the answer.

what i did was set the visible = true in JsonTypeInfo. In short by setting the visible = true allowed the jackson to do the following

Note on visibility of type identifier: by default, deserialization (use during reading of JSON) of type identifier is completely handled by Jackson, and is not passed to deserializers. However, if so desired, it is possible to define property visible = true in which case property will be passed as-is to deserializers (and set via setter or field) on deserialization.

Refer the doc here for more understanding. https://fasterxml.github.io/jackson-annotations/javadoc/2.4/com/fasterxml/jackson/annotation/JsonTypeInfo.html

Below is the code

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME , 
visible = true,
property = "credentialType")
@JsonSubTypes({
        @JsonSubTypes.Type(value = CardCredentialDto.class, name = "card"),
        @JsonSubTypes.Type(value = MobileCredentialDto.class, name = "mobile"),
})
@Getter
@Setter
public class CredentialDto {
   @JsonProperty(value = "credentialType")
    private CredentialType credentialType;

    @JsonCreator
    public CredentialDto(@JsonProperty("credentialType") final String credentialType) {
        this.credentialType = CredentialType.valueOf(credentialType);
    }

    public CredentialDto() {

    }

      public void setCredentialType(final CredentialType credentialType) {
        this.credentialType = CredentialType.MOBILE;
    }
}

and the json will look like this

{
    "credential": [
        {
            "credentialType": "mobile",
            "credentialName": "cred-2",
            "email": "s@s.com"
        },
        {
            "credentialType": "card",
            "credentialNumber": "1"
        }
    ]
}