[英]Linq Query With Entities and Group By
我有如下所示的实体(首先使用.NET代码和存储库模式):
public abstract class BaseContent : Entity
{
public Guid ID { get; set; }
public virtual ICollection<AssignedMedia> AssignedMedias { get; set; }
}
public partial class Library : BaseContent
{
public Library()
{
this.AssignedMedias = new List<AssignedMedia>();
}
}
public class Media : BaseContent
{
public Media()
{
this.AssignedMedias = new List<AssignedMedia>();
}
}
public class AssignedMedia : Entity
{
public int ID { get; set; }
//BaseContent reference ID
public Guid AssignedId { get; set; }
public Guid MediaId { get; set; }
public virtual Media Media { get; set; }
public virtual BaseContent BaseContent { get; set; }
}
然后我尝试以分组方式获取查询(如Dictionary <string,List <Media >>)! 例如:
var list = from bc in Libraries
join a in AssignedMedias on bc.ID equals a.AssignedId
join m in Medias on a.MediaId equals m.ID
select new {
LibraryName = bc.Name, MediaList = ???
};
你并不需要使用一个join
时,你已经正确映射实体关联。 您可以这样编写查询:
var libraryAssignedMedia = Libraries.ToDictionary(
l => l.Name, // Key selection.
l => l.AssignedMedias.Select(am => am.Media)); // Value selection.
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