WCF RIA Services & EF - Tip: Silverlight端访问外键关联实体

问题：在Domain Service中使用EF 4 实现如下数据访问，通过Include语句获得Job所关联的Vehicle实体

public IQueryable<Job> GetRunsByVehicleDate(int vehicleID, DateTime date)
{
date = date.Date;
DateTime dateNext = date.AddDays(1);
var result = this.ObjectContext.Jobs.Include("Vehicle").Include("Location").Include("TimeSlot")
.Where(j => j.JobDate >= date && j.JobDate <= dateNext && j.VehicleID == vehicleID)
.OrderBy(j => j.JobDate);
return result;

}

然而在Silverlight端，job.Vehicle 得到的却是null

原因：RIA没有将关联实体在客户端代码上正确生成

解决：使用Include 属性并修饰Job实体如下，

[MetadataType(typeof(JobMetaData))]
partial class Job : IEntity
{

public class JobMetaData
{
[Include]
public Vehicle Vehicle { get; set; }

[Include]
public Location Location { get; set; }

}
}

注意：Include来自 System.ServiceModel.DomainServices.Server.dll at path like

C:/Program Files (x86)/Microsoft SDKs/RIA Services/v1.0/Libraries/Server