我有两个表News和NewsComments。我遵循命名规则
结构新闻评论
public class NewsComment : BaseComment
{
public int NewsId { get; set; }
public virtual News News { get; set; }
}
但是查询返回异常无效的列名称“News_Id”。我知道在与表无关的列中创建此异常的原因。
CREATE TABLE [dbo].[NewsComments](
[Id] [int] IDENTITY(1,1) NOT NULL,
[NewsId] [int] NOT NULL,
[Text] [varchar](max) NOT NULL,
[UserId] [int] NOT NULL,
[CommentDate] [datetime] NOT NULL,
[Ip] [varchar](40) NOT NULL, CONSTRAINT [PK_NewsComments] PRIMARY KEY CLUSTERED([Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
BaseComment
public abstract class BaseComment : BasePersistentEntity, IComment
{
public int UserId { get; set; }
public virtual BaseUser User { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "CommentText")]
public string Text { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "CommentDate")]
public DateTime CommentDate { get; set; }
public string Ip { get; set; }
}
新闻
public class News : BaseContent
{
[Display(ResourceType = typeof(NewsResurce), Name = "NewsImage")]
public string NewsImage { get; set; }
public virtual ICollection<NewsCommentView> CommentViews { get; set; }
}
基本内容
public abstract class BaseContent : BasePersistentEntity
{
[Display(ResourceType = typeof(FrameworkResurce), Name = "Keywords")]
public string Keywords { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "TitleTranslit")]
public string TitleTranslit { get; set; }
[Required(ErrorMessageResourceType = typeof(FrameworkResurce), ErrorMessageResourceName = "IsTextEmpty")]
[Display(ResourceType = typeof(FrameworkResurce), Name = "Title")]
public string Title { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "Description")]
public string Description { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "Contents")]
public string Contents { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "DatePublish")]
public DateTime DatePublish { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "AuthorPublish")]
public string AuthorPublish { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "Author")]
public string Author { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "AuthorUrl")]
public string AuthorUrl { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "Views")]
public int Views { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "Comments")]
public int Comments { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "IsComment")]
public bool IsComment { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "SumVote")]
public int SumVote { get; set; }
[Display(ResourceType = typeof(FrameworkResurce), Name = "VoteCount")]
public int VoteCount { get; set; }
[NotMapped]
[Display(ResourceType = typeof(FrameworkResurce), Name = "Rating")]
public double Rating
{
get
{
if (VoteCount > 0)
{
return Math.Round((float)SumVote/VoteCount, 2);
}
return 0;
}
}
}
查询
private IEnumerable<NewsComment> GetComments()
{
var news = NewsCommentRepository.AllIncluding(c=>c.User,c=>c.News);
return news;
}
private DataRepository<NewsComment> NewsCommentRepository
{
get { return DataRepository<NewsComment>.Repository; }
}
数据存储库
public class DataRepository<T> where T : BasePersistentEntity
{
public static DataRepository<T> Repository
{
get
{
return new DataRepository<T>();
}
}
private readonly SGNContext<T> context = new SGNContext<T>();
public IQueryable<T> All
{
get { return this.context.Table; }
}
public IQueryable<T> AllIncluding(params Expression<Func<T, object>>[] includeProperties)
{
IQueryable<T> query = this.context.Table;
return includeProperties.Aggregate(query, (current, includeProperty) => current.Include(includeProperty));
}
public T Find(int id)
{
return this.context.Table.Find(id);
}
public void InsertOrUpdate(T country)
{
if (country.Id == default(int))
{
// New entity
this.context.Table.Add(country);
Save();
}
else
{
// Existing entity
this.context.Entry(country).State = EntityState.Modified;
Save();
}
}
public void Delete(int id)
{
var country = this.context.Table.Find(id);
this.context.Table.Remove(country);
this.Save();
}
private void Save()
{
this.context.SaveChanges();
}
}
在哪里使用GetComments
[GridAction]
public ActionResult AjaxCommentsBinding()
{
return View(new GridModel<NewsComment>
{
Data = GetComments()
});
}
新闻评论查看
CREATE VIEW [dbo].[NewsCommentViews]
AS
SELECT dbo.NewsComments.NewsId, dbo.NewsComments.Text, dbo.NewsComments.UserId, dbo.NewsComments.CommentDate, dbo.NewsComments.Ip,
dbo.Roles.RoleName, dbo.Users.UserName, dbo.Users.DateRegistered, dbo.NewsComments.Id, dbo.Users.Avatar
FROM dbo.NewsComments INNER JOIN
dbo.Users ON dbo.NewsComments.UserId = dbo.Users.Id INNER JOIN
dbo.Roles ON dbo.Users.RoleId = dbo.Roles.Id
新闻评论查看
[Table("NewsCommentViews")]
public class NewsCommentView : NewsComment
{
public string RoleName { get; set; }
public string UserName { get; set; }
public DateTime DateRegistered { get; set; }
public string Avatar { get; set; }
}
最佳答案
问题在于News
和NewsCommentView
之间的关系:关系的一端是News.CommentViews
集合。但是另一端是,而不是您可能期望的 NewsCommentView.News
。为什么?因为属性News
不是在NewsCommentView
类上声明为而是在基类 NewsComment
上声明的,而不是。现在,EF不允许实体参与与导航属性的关系,该导航属性不是在该实体类本身上的声明为而是仅在基类中声明的。
因此,由于您没有Fluent映射,因此EF仅按约定定义所有关系。怎么了?News
具有声明的导航属性CommentViews
并指向NewsCommentView
类。 News
类型的逆属性,该属性是NewsCommentView
类中声明为NewsCommentView
类中公开。 NewsCommentViews
中必要的外键列将具有标准的常规名称。 NameOfEntityClass_PKPropertyName
-> News_Id
您在 View 中的真实姓名是NewsId
。因此,EF会查询不存在的News_Id
列,因此是异常(exception)。
当您的MVC-View访问NewsComment.News.CommentViews
时,可能是由于延迟加载而触发了异常。
您可以通过在Fluent API中显式指定FK列名称来解决此问题(据我所知,没有Fluent映射没有其他方法):public class MyContext : DbContext
{
// ...
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<News>()
.HasMany(n => n.CommentViews)
.WithRequired() // <- no param because not exposed end of relation,
// nc => nc.News would throw an exception
// because nc.News is in the base class
.Map(a => a.MapKey("NewsId"));
}
}
但是注意:注意NewsCommentView.News
是而不是属于News.CommentViews
的关系的另一端。这意味着,如果您的NewsCommentView
集合中有一个News.CommentViews
,则NewsCommentView.News
会将而不是指向该News
对象。另一端不可见,并且未在模型中暴露。上面的映射仅解决了FK列名问题,但没有更改约定将创建的关系(除非将关系更改为必填而不是可选)。
关于entity-framework - Entity Framework 4.1无效的列名,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/7055962/