Question

我是MongoDb和Morphia的新手试图学习如何更新我的文档。

我无法从此页面看到/了解如何操作：
http://www.mongodb.org

我的文档如下所示:(这可能是一些错误）

@Entity
public class UserData {

    private Date creationDate;
    private Date lastUpdateDate;

    @Id private ObjectId id;
    public String status= "";
    public String uUid= "";


    public UserData() {
        super();
        this.statistic = new Statistic();
        this.friendList = new FriendList();
    }

    @Embedded
    private Statistic statistic;
    @Embedded
    private FriendList friendList;

    @PrePersist
    public void prePersist() {
        this.creationDate = (creationDate == null) ? new Date() : creationDate;
        this.lastUpdateDate = (lastUpdateDate == null) ? creationDate : new Date();
    }
}

在该页面上，我看不到他们描述如何更新具有特定UserData的{{1}}的任何地方如uUid

那样update UserData.status

这是我认为我应该使用的：

uUid=123567

// morphia默认更新是更新所有UserData文档，以便如何更新选定的文档

ops=datastore.createUpdateOperations(UserData.class).update("uUid").if uuid=foo..something more here..

Answer 1

我想这就是你想要的：

query = ds.createQuery(UserData.class).field("uUid").equal("1234");
ops = ds.createUpdateOperations(UserData.class).set("status", "active");

ds.update(query, ops);

Answer 2

morphia界面有点笨拙且文档不清楚......但只更新单个特定文档的方法实际上已在the page Erik referenced 上演示：

// This query will be used in the samples to restrict the update operations to only the hotel we just created.
// If this was not supplied, by default the update() operates on all documents in the collection.
// We could use any field here but _id will be unique and mongodb by default puts an index on the _id field so this should be fast!
Query<Hotel> updateQuery = datastore.createQuery(Hotel.class).field("_id").equal(hotel.getId());

<强> ...

// change the name of the hotel
ops = datastore.createUpdateOperations(Hotel.class).set("name", "Fairmont Chateau Laurier");
datastore.update(updateQuery, ops);

此外，a different documentation page显示了一种聪明的方法来隐藏实体类本身内的繁琐查询：

@Entity
class User
{
   @Id private ObjectId id;
   private long lastLogin;
   //... other members

   private Query<User> queryToFindMe()
   {
      return datastore.createQuery(User.class).field(Mapper.ID_KEY).equal(id);
   }

   public void loggedIn()
   {
      long now = System.currentTimeMillis();
      UpdateOperations<User> ops = datastore.createUpdateOperations(User.class).set("lastLogin", now);
      ds.update(queryToFindMe(), ops);
      lastLogin = now;
   }
}

morphia和如何更新现有文档字段

2 个答案: