问题描述
我正在创建一个具有2个一对多关系的实体.事件具有用户字段和位置字段.我正在尝试使用自动查询，但是此代码始终返回一个空列表.
I'm creating a an entity with 2 one-to-many relationships. An Event has a User field and a Place field. I'm trying to use the automatic-query, but this code always returns an empty list.
User user = new User("[email protected]","Maurizio Pozzobon","01","hash","facebook");
user.insert();
Place place = new Place("posto","bel posto",null,null);
place.insert();
Event e =new Event(user,place, "Festa","Questa è una gran bella festa",null,new Date(),(long) 10,false,null);
e.insert();
List<Event> l =user.events.fetch();
事件类是
public class Event extends Model{
@Id
public Long id;
...
//Relazioni
public User user;
public Place place;
...
public Event(User user, Place place,String nome, String descrizione, String uRLImmagine, Date dataInizio, Long durata, Boolean isRicorrente, Long ricorrenza) {
this.user=user;
this.place=place;
...
}
...
}
如果我这样更改Event类
If I change the Event class like this
public class Event extends Model{
@Id
public Long id;
...
//Relazioni
public User user;
//public Place place;
...
public Event(User user, Place place,String nome, String descrizione, String uRLImmagine, Date dataInizio, Long durata, Boolean isRicorrente, Long ricorrenza) {
this.user=user;
//this.place=place;
...
}
...
}
上面的相同代码返回一个包含一个事件的列表(我所期望的)
The same code above returns a list with one Event in it (what I expected)
这是Place类
public class Place extends Model {
@Id
public Long id;
public String nome;
public String descrizione;
public String uRLImmagine;
public String indirizzo;
//Relazioni
// public User user;
//@Filter("place")
//public Query<Event> events;
private Set<Long> idEvents = new HashSet<Long>();
private Set<Long> idPlaceVotes = new HashSet<Long>();
private Set<Long> idPlaceComments = new HashSet<Long>();
public Place(/*User user,*/ String nome, String descrizione, String uRLImmagine,String indirizzo) {
// this.user=user;
this.nome = nome;
this.descrizione = descrizione;
this.uRLImmagine = uRLImmagine;
this.indirizzo = indirizzo;
}
static Query<Place> all() {
return Model.all(Place.class);
}
public static Place findById(Long id) {
return all().filter("id", id).get();
}
public String toString() {
return nome;
}
public static void delete(Long id) {
findById(id).delete();
}
}
这是User类
public class User extends Model {
@Id
public Long id;
public String nome;
public String email;
public String webId; //ID of the user in the provider website
public String passwordHash;
public String service;
//Relazioni
@Filter("user")
public Query<Event> events;
public User(String email, String name,String webId, String passwordHash, String service) throws Exception {
if (email!=null)
this.email=email;
else
throw new Exception("An email is required");
if (name!=null)
this.nome=name;
else
throw new Exception("A name is required");
if (webId!=null)
this.webId=webId;
else
throw new Exception("A webId is required");
this.passwordHash=passwordHash;
this.service = service;
}
public void setEmail(String email) throws Exception{
if (email!=null)
this.email=email;
else
throw new Exception("An email is needed");
}
static Query<User> all() {
return Model.all(User.class);
}
public static User findById(Long id) {
return all().filter("id", id).get();
}
public static User findByEmail(String email){
return all().filter("email", email).get();
}
public String toString() {
return nome;
}
}
MyModel是siena.Model的超类，但是正确地知道它没有任何用处，因此我将其改回了Model.我在游戏1.1上使用play-siena 1.5
MyModel was a super class of siena.Model, but right know it doesn't do anything useful so I changed it back to Model.I'm using play-siena 1.5 on play 1.1
推荐答案
我发现了您的问题:)
这是一个已知问题，但我每次都忘记它.
在您的事件中，只需声明@Column:
This is a known issue but I forget it each time.
In your event, simply declare the @Column:
public class Event extends Model{
@Id
public Long id;
@Column("user")
public User user;
@Column("place")
public Place place;
}
由于User和Place分别具有一个名为"id"的键字段，并且在没有@Column的情况下，Siena默认使用键字段名，因此当GAE尝试通过字段"id"查找对象时会发生冲突.
我将尝试在Siena v1.0.0中更正此问题(并且您已经可以在Play中透明地使用从v1.0.0中继生成的siena.jar)
As User and Place have each a key field named "id" and the key field name is used by default by Siena when there is no @Column, there is a collision when GAE tries to find the object by field "id".
I will try to correct this in Siena v1.0.0 (and you can already use siena.jar generated from v1.0.0 trunk transparently in Play)
致谢帕斯卡
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