Google App Engine Java：查询子对象

Question

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.

Answer 1

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.