Java GAE数据存储-嵌套类上的查询筛选器

我正在使用Java&GAE数据存储来存储、管理和检索我的应用程序的一些数据

基本上我有两类：顾客和商店。这个想法是，一个客户可以有多个相关的商店，许多客户可以存在

客户的结构如下所示：

<Customer>
   <id>id1</id>
       <Stores>
           <Store>
               <storeId>100</storeId>
               <city>Venice</city>
           </Store>
           <Store>
                <storeId>200</storeId>
                <city>Milan</city>
           </Store>
           <Store>
                <storeId>300</storeId>
                <city>Venice</city>
           </Store>
       </Stores>
 </Customer>

<Customer>
    <id>id1</id>
       <Stores>
           <Store>
               <storeId>100</storeId>
               <city>Venice</city>
           </Store>
           <Store>
               <storeId>300</storeId>
               <city>Venice</city>
           </Store>
        </Stores>
</Customer>
<Customer>
    <id>id2</id>
       <Stores>
           <Store>
               <storeId>700</storeId>
               <city>Venice</city>
           </Store>
        </Stores>
</Customer>

我想得到的是每一位在特定城市有商店的顾客。。但是，客户对象也需要有这些商店！像这样：

<Customer>
   <id>id1</id>
       <Stores>
           <Store>
               <storeId>100</storeId>
               <city>Venice</city>
           </Store>
           <Store>
                <storeId>200</storeId>
                <city>Milan</city>
           </Store>
           <Store>
                <storeId>300</storeId>
                <city>Venice</city>
           </Store>
       </Stores>
 </Customer>

<Customer>
    <id>id1</id>
       <Stores>
           <Store>
               <storeId>100</storeId>
               <city>Venice</city>
           </Store>
           <Store>
               <storeId>300</storeId>
               <city>Venice</city>
           </Store>
        </Stores>
</Customer>
<Customer>
    <id>id2</id>
       <Stores>
           <Store>
               <storeId>700</storeId>
               <city>Venice</city>
           </Store>
        </Stores>
</Customer>

---

看看下面的代码是否符合您的要求

Query query = pm.newQuery(Customer.class);
query.declareVariables("Customer store");
query.setFilter(
    "this.stores.contains(store) && store.city == \"SomeCity\"");
Collection result = (Collection)query.execute();

---

谢谢spiritwalker，它几乎起作用了。。我可以成功地检索客户，但结果对象中没有商店。。我还用客户和商店类代码更新了我的问题。谢谢你的帮助事实上，我遗漏了一行代码，用来显示商店。我的错！您的解决方案有效，谢谢！

@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true")
@Cacheable("false")
@FetchGroup(name="customerstores", members={@Persistent(name="storeList")})
public class Customer {

    @PrimaryKey
@Persistent
private String id= "";

    @Persistent
    @Unowned
private List<Store> storeList;

    //getters and setters here
    ....
}

@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable = "true")
@Cacheable("false")
public class Store {

    @PrimaryKey
@Persistent
private String storeUniqueKey = "";

    @Persistent
    private String city = "";

    //getters and setters here
    ....
}

Query query = pm.newQuery(Customer.class);
query.declareVariables("Customer store");
query.setFilter(
    "this.stores.contains(store) && store.city == \"SomeCity\"");
Collection result = (Collection)query.execute();