Rename ObjectId _id to id in jackson deserialization with Jongo and MongoDB

Question

I\'ve just started working on a project using the play framework,jongo and MongoDB. The project was initially written in Play 2.1 with pojos with an String id field annotat

Answer 1

ObjectIdSerializer always writes property mapped with @ObjectId to a new instance of ObjectId. This is wrong when you map this property to a String.

To avoid this behaviour, I've write a NoObjectIdSerializer :

public class NoObjectIdSerializer extends JsonSerializer<String> {
    @Override
    public void serialize(String value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
        jgen.writeString(value);
    }
}

used like this :

@ObjectId
@JsonSerialize(using = NoObjectIdSerializer.class)
protected final String _id;

There is an open issue.

Answer 2

I think that there is an annotation in jackson that allows you to change the property name, I think is : @JsonProperty but you can see all the possible annotations in this link:

https://github.com/FasterXML/jackson-annotations/wiki/Jackson-Annotations

I hope this solve your problem

Answer 3

You can try using @JsonValue, Jongo does not seem to use them, but without any response from the developers this behaviour might be subject to change in future releases.

@JsonValue
public Map<String, Object> getJson() {
    Map<String, Object> map = new HashMap<>();
    map.put("name", name);
    map.put("id", id);
    return map;
}

The more proper solution would be to try combining @JsonView with @Id annotation
Remember to specify which View to use on Jongo's ObjectMapper and your Jackson ObjectMapper (the one to use in REST layer, I presume)

@Id
@JsonView(Views.DatabaseView.class)
private String id;

@JsonView(Views.PublicView.class)
public String getId() {
    return id;
}

Answer 4

The Jongo's behaviour has changed since 1.1 for a more consistent handling of its owns annotations.

If your '_id' is a String and you want this field to be stored into Mongo as a String then only @Id is needed.

@Id + @ObjectId on a String property means :

"My String property named 'foo' is a valid ObjectId. This property has to be stored with the name '_id' and have to be handled as an ObjectId."