Google App Engine Java：查询子对象
问题与 Google 应用程序引擎 Java 有关。
我有两个对象员工，地址。 每个员工都有一个初始化地址列表，并且还有一个当前/退休/离开/解雇的字符串状态。
现在我想获取休斯顿所有现有员工的列表。
Class Employee {
@Persistent(mappedBy="employee")
List<Address> addresses;
String status;
}
Class Address {
@Persistent
private Employee employee;
String address1;
String city;
String zip;
}
在我的数据库类上如何告诉我的查询执行我需要的操作。
Query query = pm.newQuery(Employee.class, whereClause.toString());
List<Employee> empList = (List<Employee>) query.executeWithArray(paramValues.toArray());
当我将状态参数设置为当前时，它会给我一个当前员工的列表，我如何将“休斯顿”的条件添加到我的查询中，这样我就不必自己进行过滤。
我觉得我错过了一些东西。感谢您的帮助。
Question is related to Google app engine Java.
I have two objects Employee, Address.
Each employee has a list of addresses init and also has a String status of current/retired/left/fired.
Now I want to get a list of all my current employees who are Houston based.
Class Employee {
@Persistent(mappedBy="employee")
List<Address> addresses;
String status;
}
Class Address {
@Persistent
private Employee employee;
String address1;
String city;
String zip;
}
On my db class how do tell my query to do what i need.
Query query = pm.newQuery(Employee.class, whereClause.toString());
List<Employee> empList = (List<Employee>) query.executeWithArray(paramValues.toArray());
When I set my status parameter to current, it will give me a list of current employees, how do i add the condition of "Houston" into my query so that I dont have to do the filter by myself.
I feel that I am missing something. Appreciate you help.
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这需要联接，因此在 App Engine 上的查询中是不可能的。您最好的选择是查询休斯顿的所有地址实体，然后获取其员工记录并按状态过滤（在内存中）。
This would require a join, and so isn't possible in a query on App Engine. Your best option would be to query on all address entities from Houston, then fetch their Employee records and filter (in memory) by status.