使用Jackson PTH和Spring Data的Java到JSON序列化MongoDB DBRef会生成额外的目标属性

Question

当从Java序列化为JSON时,target当使用@DBRef具有延迟加载和Jackson的多态类型处理的Spring Data MongoDB 注释时,Jackson 为引用的实体生成额外的属性.为什么会发生这种情况,是否可以省略额外的target财产？

代码示例

@Document(collection = "cdBox")
public class CDBox {
  @Id
  public String id;

  @DBRef(lazy = true)
  public List<Product> products;
}

@Document(collection = "album")
public class Album extends Product {
  @DBRef(lazy = true)
  public List<Song> songs;
}

@Document(collection = "single")
public class Single extends Product {
  @DBRef(lazy = true)
  public List<Song> songs;
}

@Document(collection = "song")
public class Song {
  @Id
  public String id;

  public String title;
}

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME,
                    property = "productType",
                    include = JsonTypeInfo.As.EXTERNAL_PROPERTY)
@JsonSubTypes(value = {
    @JsonSubTypes.Type(value = Single.class),
    @JsonSubTypes.Type(value = Album.class)
})
public abstract class Product {
  @Id
  public String id;
}

生成的JSON

{
  "id": "someId1",
  "products": [
    {
      "id": "someId2",
      "songs": [
        {
        "id": "someId3",
        "title": "Some title",
        "target": {
          "id": "someId3",
          "title": "Some title"
          }
        }
      ]
    }
  ]
}

Answer 1

目标字段由Spring Data添加,因为它是一个惰性集合.所以它就像Hibernate for JPA中的datahandler等.

选项1:要忽略它们,您只需在类级别添加@JsonIgnoreProperties(value = {"target"})

@Document(collection = "song")
@JsonIgnoreProperties(value = { "target" })
public class Song {
 ...
}

选项2:使集合不懒惰