java - 如何从吗啡中的 ArrayList 中删除特定元素？

Question

我在 Morphia Entity 类中使用 ArrayList 的继承 @Embedded 引用。

@Entity
public class First {
  @Embedded private List<Second> secondClass;
  private String title;
  private Long id;
  ...  getter and setter .. methods
}

@Embedded
public class Second {
  @Embedded private List<Third> thirdClass;
  private String titleSecond;
  ...  getter and setter .. methods
}

@Embedded
public class Third {
  private String titleThird;
  private String logoUrl
  ...  getter and setter .. methods
}

JSON

{
  "secondClass": [{
    "thirdClass": [{
      "titleThird": "Java",
      "logoUrl": "http://www.artsfon.com/pic/201510//artsfon.com-72885.jpg",
    }, {
      "titleThird": "ios",
      "logoUrl": "http://www.artsfon.com/pic//1920x1080/artsfon.com-72885.jpg",
    }],
    "titleSecond": "Developer"
  }],
  "title": "Software Developer",
  "id" : 1234567890
}

问题

1) 如何删除给定titleSecond和id值的元素？

2) 如何删除给定titleThird和id值的元素？

首先我尝试了以下实现:

UpdateOperations<First> ops;
Query<First> updateQuery = datastore.createQuery(First.class).filter("id", Long.parseLong(id.trim()));

ops = datastore.createUpdateOperations(First.class).disableValidation().removeAll("secondClass.titleSecond", "Developer");
datastore.update(updateQuery, ops);

但它抛出映射错误:

Write failed with error code 16837 and error message 'cannot use the part (secondClass of secondClass.titleSecond) to traverse the element.

如何执行问题 1 和 2 的操作？任何帮助将不胜感激。

可能相关的问题:In Morphia how can i update one embedded Object inside an ArrayList

Answer 1

创造了这样的记录。

db.myCollection.insertMany([{
        "_id" : ObjectId("58609ed483ce6037ec33fc8c"),
        "secondClass" : [
                {
                        "thirdClass" : [
                                {
                                        "titleThird" : "Java",
                                        "logoUrl" : "http://www.artsfon.com/pic"
                                },
                                {
                                        "titleThird" : "ios",
                                        "logoUrl" : "http://www.artsfon.com/pic"
                                }
                        ],
                        "titleSecond" : "Developer"
                }
        ],
        "title" : "Software Developer"
}])

我的第一个类。其余类(class)相同。

@Entity("myCollection")
public class First {

    @Id
    private ObjectId id;
    private String title;
    @Embedded
    private List<Second> secondClass;

第一部分的答案。

UpdateOperations<First> ops;
Query<First> updateQuery = datastore.createQuery(First.class).field("_id").equal(new ObjectId("58609ed483ce6037ec33fc8c"));

Second second = new Second();
second.setTitleSecond("Developer");
ops = datastore.createUpdateOperations(First.class).disableValidation().removeAll("secondClass", second);
datastore.update(updateQuery, ops);

第一部分的替代解决方案。

UpdateOperations<First> ops;
Query<First> updateQuery = datastore.createQuery(First.class).field("_id").equal(new ObjectId("58609ed483ce6037ec33fc8c"));

ops = datastore.createUpdateOperations(First.class).disableValidation().removeAll("secondClass", new BasicDBObject("titleSecond", "Developer"));
datastore.update(updateQuery, ops);

第二部分的答案。

UpdateOperations<First> ops;
Query<First> updateQuery = datastore.createQuery(First.class).field("_id").equal(new ObjectId("58609ed483ce6037ec33fc8c")).field("secondClass.thirdClass.titleThird").equal("ios");

ops = datastore.createUpdateOperations(First.class).disableValidation().removeAll("secondClass.$.thirdClass", new BasicDBObject("titleThird", "ios"));
datastore.update(updateQuery, ops);