Objectify/AppEngine/Java: Many-many relationship

Question

I use Objectify in AppEngine with JAva. I would like to model a many-many relationship in which the resolution entity has additional fields, as below

@Entity
public class Account {
    public @Id Long id;
    public String name;
}

@Entity
public class Baby {
    @Id public Long id;
    public String name;
}

@Entity
public class AccountBaby {
    public @Id Long id;
    @Index
    @ApiResourceProperty(ignored = AnnotationBoolean.TRUE)
    public Ref<Account> account;

    @Index
    @ApiResourceProperty(ignored = AnnotationBoolean.TRUE)
    public Ref<Baby> baby;

    public int permission;
}

If I follow this model, I can not query list of account for given baby's id (or list of baby for given account's id) as the query below

List<AccountBaby> babies = OfyService.ofy().load().type(AccountBaby.class).filter("account=",
                Key.create(Account.class, accountId)).list();

Is they any other way to query or model this relationship?

Answer 1

“account =”中需要一个空格。或者你可以放弃隐含的“=”。

您实际搜索的是一个名为“account =”的属性（可以使用低级别api保存在数据存储区中）。这在filter()方法的javadoc中提到。