Save an embedded document _id as ObjectId but display it as a String

Question

I want to save the _id in Review class as an ObjectId but when I query it I want it to be displayed as a String and not the {"timestamp", "machineIdentifier", etc.}

Here are the classes I made:

@Document
public class Catalog {
    ....
    private List<Review> reviews;
    ....
}

public class Review {
    @Id
    private ObjectId _id = new ObjectId();
    private String userid;
    private String username;
    private String reviewstring;
}

The class Review in the mongodb is an embedded document.

When I query for a certain review with the _id as a String, it returns null. How can I display the ObjectId as a String during queries but let it remain as an ObjectId?

Answer 1

@JsonSerialize（使用 = ToStringSerializer.class）