集合到达客户端时为空

Question

我的一个实体有一个 EntitySet<>具有[组合]、[包含]和[关联]属性的属性。我在域服务中填充此集合，但当我在客户端收到它时检查其内容时，该集合为空。

我正在使用 Silverlight 4 RTM 以及 RIA Services 1.0 RTM。

有什么想法我做错了吗？

这是我的服务端的代码：

public class RegionDto
{
  public RegionDto()
  {
      Cities = new EntitySet<CityDto>();
  }

  [Key]
  public int Id { get; set; }
  public string Name { get; set; }

  [Include]
  [Composition]
  [Association("RegionDto_CityDto", "Id", "RegionId")]
  public EntitySet<CityDto> Cities { get; set; }
}

public class CityDto
{
  [Key]
  public int Id { get; set; }
  public int RegionId { get; set; }
  public string Name { get; set; }
}

[EnableClientAccess()]
public class RegionDomainService : LinqToEntitiesDomainService<RegionEntities>
{
  public IEnumerable<RegionDto> GetRegions()
  {
      var regions = (ObjectContext.Regions
          .Select(x => new RegionDto
          {
              Id = x.ID,
              Name = x.Name
          })).ToList();

      foreach (var region in regions)
      {
          var cities = (ObjectContext.Cities
              .Where(x => x.RegionID == region.Id)
              .Select(x => new CityDto
              {
                  Id = x.ID,
                  Name = x.Name
              })).ToList();

          foreach (var city in cities)
          {
              region.Cities.Add(city);
          }
      }

      //  each region's Cities collection is populated at this point
      //  however when the client receives it, the Cities collections are all empty
      return regions;
  }
}

Answer 1

好的。问题是我的域服务在实例化 CityDto 类时没有设置它们的 RegionID 属性。因此，即使将城市放入 RegionDto 的集合中，客户端上的 RIA 服务也无法将关联拼凑在一起。

将我的域服务更改为此解决了问题。

[EnableClientAccess()]
public class RegionDomainService : LinqToEntitiesDomainService<RegionEntities>
{
  public IEnumerable<RegionDto> GetRegions()
  {
      var regions = (ObjectContext.Regions
          .Select(x => new RegionDto
          {
              Id = x.ID,
              Name = x.Name
          })).ToList();

      foreach (var region in regions)
      {
          var cities = (ObjectContext.Cities
              .Where(x => x.RegionID == region.Id)
              .Select(x => new CityDto
              {
                  Id = x.ID,
                  Name = x.Name,
                  RegionId = region.Id
              })).ToList();

          foreach (var city in cities)
          {
              region.Cities.Add(city);
          }
      }

      //  each region's Cities collection is populated at this point
      //  however when the client receives it, the Cities collections are all empty
      return regions;
  }
}