小编Nic*_*wyn的帖子

我有以下抽象类:

public abstract class StandardTimeStamp {

  @Temporal(TemporalType.TIMESTAMP)
  @Column(nullable = false)
  @JsonIgnore
  private Date lastUpdated;

  @PreUpdate
  public void generatelastUpdated() {
    this.lastUpdated = new Date();
  }

  public Date getLastUpdated() {
    return lastUpdated;
  }

  public void setLastUpdated(Date lastUpdated) {
    this.lastUpdated = lastUpdated;
  }
}

我有一个实体是一个子类,我需要将lastUpdate值发送到浏览器,所以我需要覆盖@JsonIgnore.我尝试过一些东西,下面的代码就是其中之一:

public class MyEntity extends StandardTimestamp implements Serializable {

  @Column(name = "LastUpdated")
  private Date lastUpdated;

  @JsonIgnore(false)
  @Override
  public Date getLastUpdated() {
    return lastUpdated;
  }
}

这确实在JSON响应上添加了lastUpdated属性,但是当它在数据库中不为null时,其值为null.我在子类中有其他日期可以工作,但它们不会被超类中的@IgnoreJson隐藏.

有什么想法吗？

我一直在深入研究 MongoDB，并发现了一种特别有趣的模式来存储文档之间的关系。此模式涉及包含引用子文档的 id 数组的父文档，如下所示：

//Parent Schema
export interface Post extends mongoose.Document {
  content: string;
  dateCreated: string;
  comments: Comment[];
}

let postSchema = new mongoose.Schema({
  content: {
    type: String,
    required: true
  },
  dateCreated: {
    type: String,
    required: true
  },
  comments: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Comment' }] //nested array of child reference ids
});

和被引用的孩子：

//Child Schema
export interface Comment extends mongoose.Document {
  content: string;
  dateCreated: string;
}

let commentSchema = new mongoose.Schema({
  content: {
    type: String,
    required: true
  },
  dateCreated: { …