使用Key.Id查询Google App Engine数据存储区(Query Google App Engine Datastore with Key.Id)

使用Key.Id查询Google App Engine数据存储区(Query Google App Engine Datastore with Key.Id)

我正在将一个简单的Java应用程序部署到Google App Engine。

我有一个包含Key的简单JPA实体作为我生成的ID。

import javax.persistence.*; @Entity public class MyEntity { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private com.google.appengine.api.datastore.Key key; ...

一旦我坚持这个对象。 我可以像这样查看钥匙的ID ...

long id = entity.getKey().getId();

你知道我怎样才能使用相同的ID来获得我的实体吗？ 像这样的东西...

Query query = em.createQuery("SELECT e FROM MyEntity e WHERE e.key.id = :myId"); query.setParameter("myId", id);

上述不起作用。 我知道我可以通过将Key作为参数传递回来，但我想知道是否可以使用long id。

I'm deploying a simple Java app to Google App Engine.

I have a simple JPA Entity containing a Key as my generated ID.

import javax.persistence.*; @Entity public class MyEntity { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private com.google.appengine.api.datastore.Key key; ...

Once I persisted this object. I can view the key's ID like so...

long id = entity.getKey().getId();

Do you know how I can I use the same Id to get my entity back? Something like this...

Query query = em.createQuery("SELECT e FROM MyEntity e WHERE e.key.id = :myId"); query.setParameter("myId", id);

The above doesn't work. I know I can get it back by passing in the Key as the parameter, but I'd like to know if I could use the long id instead.

最满意答案

找到解决方案，使用KeyFactory创建一个Key并传入ID。 然后在密钥上查询。

Key key = KeyFactory.createKey(MyEntity.class.getSimpleName(), id);

Found the solution, create a Key using the KeyFactory and pass in the ID. Then Query on Key.

Key key = KeyFactory.createKey(MyEntity.class.getSimpleName(), id);