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entity-framework - Entity Framework 4.1无效的列名

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。
  • EF找不到News类型的逆属性，该属性是NewsCommentView类中声明为的。 (有一个，但是它在基类中，这不算在内。)
  • 因此，EF假定关系的另一端是，但未在NewsCommentView类中公开。
  • 未公开表示:EF没有导航属性或外键属性，并且将假定数据库表/ View NewsCommentViews中必要的外键列将具有标准的常规名称。
  • 这个常规名称是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/

    10-12 12:49
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